Author: ballisticxlr

1. Doublestar ACE FSA, 2. SB Tactical BTFA, 3. Sylvan Arms FSA 4. MDT Carbine|Carbine FSA,
5. UTG/Leapers FSA, 6. XLR FSA 7. Law Tactical FSA (and clones) 8. Hera Arms

And the winner is… I’ll tell you in a minute. First let me congratulate American and German industry for continuing the tradition of “Made in America” and “Made in Germany” labels as being indicative of excellently engineered and crafted doodads. We’re going to have a few category winners and an overall winner. Categories are Value, Compactness, Toughness, Lockup and Materials Selection.

Winner: Value
What do we mean by value? Getting the most for your money. For that, there’s no possibility of any winner other than UTG. They have the only unit that’s both double locking and under $100. For $15 plus shipping you end up with a workable if unsophisticated solution to a problem. Slickness doesn’t matter here. This is a Soviet type mindset of, “It functions? Yes. Is cheap? Yes.” with no other considerations. If they weren’t something like 5 times cheaper than any other solution I might not have been so generous.

Winner: Compactness
This is measured by displacement and it was a surprise. The DoubleStar ACE won this hands down. It adds only about 1/2″ to the length of pull. Nothing else came really close. The thinness of the adapter is simply not beatable by any other design. The rest were, on average, just over an inch thick which is enough to add to length of pull that fitment adjustments need to be made afterward. With the ACE, just install it and you’ll probably be fine not adjusting your length of pull.

Winner: Toughness
This was almost a tie between two very similar designs done in very different ways, the DoubleStar ACE and the UTG AK-47 folding adapter. Both seem to make strength and double locking priorities. Both manage to keep the cost down, seemingly as a side effect of the design. The DoubeStar ACE in it’s steel and semi-steel configurations is mindbogglingly strong. For its compactness, that’s a major coup. The UTG is also mindbogglingly strong and while it’s nothing like as compact as the ACE, it’s probably just as strong. Either were strong enough that I’d never worry about breaking it even by doing some insane things to them. There is a differentiator though, the lugs on the receiver adapter and pig nose on the DoubleStar unit, those lugs are adding serious toughness to the folder. Where others rely on just the hinge to keep it from getting twisted, the ACE adds fatass lugs. That will keep your butt stock from rotating in a way that a castle nut just doesn’t. So DoubleStar’s ACE wins Toughness cold.

Winner: Lockup
This is about how they lock up out of the box and how that lockup will survive into the future. Most designs had some wiggle. If they didn’t have wiggle they had a lockup adjustment mechanism, simple as that, with 1 glaring exception. The MDT unit had no adjustment feature and still locked up tight as a nun’s cunt. Looking at the interference fit and wear patterns, I have to predict that eventually lockup won’t be as tight and there’s no way to adjust it so MDT cannot win on this point even though I’d like them to. In this case, there was only 1 unit that had adjustable lockup, the XLR Gen2 unit. The SB-Tactical does too but they’re out of stock for MONTHS now and I’ve simply no more patience for them. They’ve got bigger problems now anyway since the ATF has decided to declare basically everything else that SBT makes is basically an NFA item. So the clear and simple winner is XLR Industries Gen 2. The Hera Arms is identical to XLR’s Gen1 unit, neither of which have lockup adjustment. So, great job to XLR industries. This is the category we all care about most when the rubber meets the road and they didn’t forget that.

Winner: Materials Selection
If XLR ever decides to make one of their units out of steel and improve the hold-open feature I’ll revisit this article and declare them the unconditional overall winner. For now though, DoubleStar ACE wins the materials selection hands down. This is limited to the push-button and all steel models though as those are where the manufacture is known to be inclusive of steel in the most important places or of all steel. Steel rules, baby.

Winner: Overall Excellence
This was not easy to decide. It comes down to what works the best now and what will work the best down the road. As much as I really love the DoubleStar ACE the square shape is in the way just a little bit and the non adjustable lock-up is a factor. Knock down 1 corner on that unit and they walk away as the winner adjustable lockup or no. I really hope they’re paying attention to this because they could tweak their design to be round or at least to have less discrete corners (think hexagon or pentagon) and then I’d sell all my other units and buy ACE’s. If they added little delrin inserts in strategic spots with set screws behind them then the lockup would be adjustable and there’d be no reason for anyone else to make a competing product, it’d be perfect for precision rifle usage. Since neither of those two things are currently the case, we have to go to the one that does the precision rifle job best and that means that the XLR Industries Gen 2 side folding adapter wins. I am pretty certain that if I could have gotten an SB-Tactical unit that they would have won simply because the design is so close to the XLR Gen 2 but, critically, the SB-Tactical unit has a lock-open feature which includes a positive lock and adjustable lockup and it’s about as compact as the XLR/Hera units and the price is ok. I just couldn’t get one to save my damned life and that’s a factor to be considered.

A big congratulations to XLR industries. You earned it. Just don’t go resting on your laurels. You know where you’re at risk of losing to innovation in the future, so go fix those things. Make a 100% steel unit. I’ll buy one. Fix your hold-open so it’s not a drag based system. I’ll buy two. Gate the pushbutton release. I’ll buy three.

What I’d like to see is for XLR and DoubleStar to both take my suggestions and then to run this comparison again but this time include test to destruction so we can see if it’ll be the folding adapter or the stock that gives up first and we’ll pit just the XLR and the ACE against each other. See who’ll rule the roost. What I’d especially like to see is SB-Tactical get their inventory shit together so I can buy their stuff and then compare it against XLR and DoubleStar.

Why did MDT not show up in any winner’s circle? The cost is high for the features, the features are very well implemented for out of the box performance but long term durability remains in question and the installation was made more difficult than it needed to be. Basically, MDT made a great swing but it was pretty far short of the fences.

Where do Sylvan Arms and Law Tactical sit? Law Tactical’s unit on a precision bolt action rifle is nearly ass but it’s one of two all steel offerings and it’s the only one that works on both AR-15s and bolt-guns. It’s near indestructible and very well thought out. Sylvan’s offering is ass on a bolt action rifle since it doesn’t offer the strength upside of a Law but offers all of the downsides. On a gas gun, I would not hesitate to use a Sylvan if I just wanted folding for transport. If I wanted folding for rapid employment, then I’m going to Dead Foot Arms.

Final Thoughts: It’s 99% sure that each of the various companies whose product I reviewed is aware of my review. To date only 1 of them has come forward to acknowledge in any way the review that they were given. That company is: DoubleStarUSA. They took the opportunity to thank me for doing a fair, open and critical review. They didn’t dispute any of my points or try to reinforce any other points. They simply said, “Thank you” for me being fair. It takes a lot of guts to look a critic in the face and say, “Thank you for being a critic.” It says a lot about who they are inside. I know today that when I go looking for my next side folding unit, I’ll check DS first and see if they’ve rounded off any corners yet and if they did then I will look no further. If not, I may or may not look further and hit up XLR Industries. I do know that it’s unlikely I’ll look much further afield than those two though. See below for the wrap-up of scores, points and value assessment. In the end, the Value column identified the winner very clearly. You can also see that the idea of functional points divided by dollars is a decent but not 100% viable way of deciding on things like this. XLR/Hera/MDT/DoubleStar placed in a tight cluster using the Value system. The problem is that UTG blew the curve so far away it became invisible for a long while. When looking at scores like this it’s important to take the highest and lowest scores and to discard them if they’re more than 3 standard deviations away from the mean of any cluster of samples. We ended up here with 2 clusters of samples and then 1 unit that was not even on the same planet as the other samples. The UTG is scoring way too differently meaning it’s of a different kind or someone is cheating. (Hint, it’s both.)

Looking at the stats, if we remove the UTG part then the SD of Value scores is .04. Adding the UTG back in changes the SD of Value points to .23. That increase of the SD by 5x tells me that that sample should be discarded as it’s of a different kind to the rest. Similarly, look at the the distribution of low Value scores and you see another cluster with an internally low SD. If we remove both the UTG and the Chinese garbage pail kid from the stats then everything tightens up. The SD of points goes from >5 to 1. What this is showing is that Chinese made stuff cannot be directly compared to American made stuff. They’re on different economic planets. This should also expose just how thorough China is when playing unfair economic games. They’ll steal intellectual property, violate patents and trademarks, use slave labor and low wage workers, use substandard materials and terrible designs or whatever else they have to do to make sure you get a pile of shit for your money and that they get your money. The table below should tell you all you need to know about geopolitics between the far east and the west.

part 1.
part 2.
part 3.
part 4.
Mid-Series Check-in.
part 5.
part 6.
Declaring the Winners

1. Doublestar ACE FSA, 2. SB Tactical BTFA, 3. Sylvan Arms FSA 4. MDT Carbine|Carbine FSA,
5. UTG/Leapers FSA, 6. XLR FSA 7. Law Tactical FSA (and clones) 8. Hera Arms

Because this might seem overly harsh, I’m putting my final paragraph at the top and the bottom so the TLDR crowd doesn’t get the wrong idea: In the end, Sylvan made a decent part. The machining is masterfully done without any visible tool marks and with ultra smooth surfaces and tight clearances. I’m not excited about the finish wear and dings on the lockup faces, the hinge height interfering with knuckles and the fact that the hold-open detent is for shit but the rest of it is great for a gas gun. The only way you can make yourself totally unsatisfied with it is to expect too much of 7075 aluminum or to put it on a bolt action rifle.

Other than the Chinese garbage pail kid and the Law Tactical, this is the only unit designed for gas-gun use that’s being tested (For right now. I’m hoping to get a Dead Foot Arms unit too.). Some salt has to be given to the amount of harsh criticism you’ll find below because the other units didn’t saddle themselves with gas gun compatibility so they could make much more excellent designs for use with bolt action rifles than Law/Sylvan/China could with a gas-gun compatible design. That said, it’s not a Law Tactical and should not be confused with one. They’re on similar but separate planets.

Like I said, it’s not a Law Tactical and that’s for sure. It does the job of alternately folding and extending well enough. It locks closed very nicely and very securely with only a tiny amount of wiggle in the lockup which is easily treated with a bit of masking tape. Locking closed is something it’s committed to doing well.

It lightly considers, on the other hand, the notion of locking in the open position before deciding firmly against that path. The button you push to open it is un-gated and sticks out enough that I guess you could theoretically inadvertently press it but I don’t think that an inadvertent press is going to matter a cold squirt of piss worth. I tried on both a bolt gun and an AR-15 to break the stock open while behind it and pressing the button against a barricade but it didn’t work. All I could do is screw up my aim and hurt my wrist.

Installation is really quite straightforward but they annoyed me with the actual instructions. Worse than MDT’s effort, Sylvan’s was instead an infuriating direction to go and watch a fucking YouTube video. Normally this might be considered an OK, even helpful, thing but the one there is presented by some gal that doesn’t seem to have full confidence in her actions or the script and so, in the end, she inspires as much confidence in the instructions as a Trabant might in its ability to be “reliable transportation”.

FYI to Sylvan Arms: Gun bunnies have to be hot to be gun bunnies. It’s in the dictionary. Back to business… https://www.youtube.com/watch?v=G-lwRVkl0zQ that’s a gun bunny (although, I have to mention that Brickell/AGC is an example of what happens when you pick the pieces to your ideal woman before seeing them all assembled together. Mistakes are made.)

Construction is reportedly 7075 Aluminum but, I found more beneath the covers. The lockup pin on the receiver-side block is steel, or at least ferrous. The locking tab that gets captured by that pin is aluminum and that greatly concerns me. The reason for the concern is that the lockup bits exhibited definite finish wear and got dinged up quite a bit by opening #4. Some of the marks really concern me given their depth and width. I think all of the lockup bits should be steel, period. This design doesn’t seem a very good place to mix aluminum and steel. Breakage seems like it will be eventual.

The ball bearings that act as detent balls are hard-as-fuck bearing steel like you’d expect. They are way harder than the hinge material though and since the detent groove is in the hinge itself the balls are just chewing the hell out of the corner of the detent groove, peening it into uselessness, and they’re progressively carving grooves in the hinge itself. It gradually makes the hold-open detent more and more non-functional and it does this early in the life of the product. This suggests that materials selection and widget design were not taken together on this feature. I suspect that the decision to go with aluminum was done to hit either a lower price point or a higher profit margin and what usually happens happened. If you add features to a thing and don’t change the price, then some included feature(s) have to be less well implemented. In this case, they compromised the Law design by using a material it wasn’t meant to use and came out with a product that’s not up to snuff when measured against its ferrous forebear.

If you’ve felt like the criticisms were a-plenty, now’s your respite. Functionality wise, it operates mostly as you’d guess except for not locking open for shit. It operates just fine as a stock extension on both AR’s and bolt guns and it does fold and it doesn’t hinder closed functionality. Well, it caused me no major hassles on my AR-15 but it might on yours. On my AR-15 there is a scope mounted super low so the charging handle has to be gripped from the top only. You can’t really get a good handle on it from the side anyway. If you go from the side with a Sylvan in place, scope or no scope, you’ll rap your knuckles on the hinge. It’s annoying, not painful but it’s still annoying and might cause you to lose your grip on the charging handle.

One other thing to note here, the bolt carrier extension it comes with is pretty heavy. No heavier than the Law unit but still, should be mentioned. The Chinese unit’s extension weighed under an ounce and feels like it was cast from pot metal. The Sylvan feels like ~3oz. Heavy enough to possibly change how your gun cycles if you’re already on the edge of your gas system being not gassed hard enough. Since I have personally never encountered an AR-15 that wasn’t over-gassed like a bitch, I’ll note that this problem is entirely theoretical for any but an extreme minority of AR owners.

Certain elements of the design are purely to satisfy AR-15 use and we have to give lip service to that fact because it compromises the bolt-action use case. One such element is how far below the buffer tube it extends. Well, on an AR-15 that’s basically unnoticeable in daily use. On a bolt gun it is obviously sticking out like a sore ‘friggin thumb. It’s not in the way really but it is there and it’s ugly as hell on a bolt gun. Looks like a wart on an ass.

I can’t say I’m disappointed in this unit for what it is meant to be so much as I think anyone using it on a bolt gun should be disappointed in themselves for not choosing a bolt-gun specific unit. It’s a gas gun unit, not a bolt gun unit and pretty much any bolt-gun unit is going to be better on a bolt gun. Duh. In the end, it’s basically a Law Tactical clone that is close but still not the real deal. From a huge hold-open detent that doesn’t do actually that, to the hardened steel ball bearings grinding grooves into to the aluminum hinge to the lockup face that begins to show wear nearly instantly. This is not confidence inspiring. I’m happy enough with it to leave it resident on an AR-15 but I would personally buy a Law or a Dead Foot Arms unit given my druthers. In this case, I’ll end up popping for the DFA and sending this unit to a good friend of mine who’d better be reading this article. Right, Bruwer?

Don’t use screwdrivers as hammers! On the points system, it got 9 of 19 points. The Sylvan lost points everywhere it could by not being used as intended. Even the UTG beat the points count that the Sylvan reaped, mostly because the UTG was not made for a gas gun and the UTG is a real double locking design. On the value scale it got .05 which is smack in between the Law Tactical and the Chinese garbage pail kid. On the arbitrary points (stars) scale, this gets 2 stars (ONLY as applied to bolt action rifles) which ties them UTG on that scale but it does it at 10x the price. As a gas gun unit, looking only at how it works on my AR-15, it’d get 3 stars because it’s markedly better at doing that job than the bolt gun job.

These things retail for $180 plus shipping. That I got mine on sale for $119 plus shipping isn’t relevant because even for $119 plus shipping it’s too damned much money for what you get by a long way IF you use it on a bolt action. If you use it on a gas gun, then you’re getting more for your money by a long way but I question if you’re getting the best from your money and I question whether or not there is a way to quantitatively answer that question. I see only qualitative answers.

On the objective points scale, well it did pretty badly there with only 9 points of 19 but, that’s why we have multiple scales to measure with. No scale will always tell you what you’re asking it to. I would personally rate it much higher than the UTG just based on the lack of blood blisters and the more sophisticated design and better materials. I would not treat it as roughly as I might a UTG unit though. So even if we’re considerate and give it some benefit of the doubt for being cross-compatible between bolt-guns and gas-guns, for a bolt-gun it’s pretty much ass and for a gas-gun it’s nothing compared to its Law Tactical big brother in durability or wise materials selection. For gas guns it’s not much more costly to go Law Tactical and for bolt guns literally any other design except the UTG would be a better option.

All the above said, I’m not yet certain that nowadays I’d pop for a Law Tactical for my AR-15 in any event. It’s not that important for me to fold that gun up that I’d make it temporarily unusable for the ability to do so. I mean, granted I have two that are folders NOW but that’s a result being young and dumb in the past and of this test and not wasting money. The tacticool factor isn’t really my jam either. I laugh at people that go too far off the tacticool cliff. I might, however, just pop for the Dead Foot Arms unit though because what you get for doubling the price over a Law unit is fire when folded and that could be a big value add to me if it doesn’t run afoul of my state’s assault weapons laws (FYI, it does). The DFA unit is basically pointless on a bolt gun because they didn’t compromise the design to allow a normal AR-15 bolt carrier to be used. They said, “Fuck that. I want my fire when folded and if that means a new bolt carrier, screw you then. New bolt carrier it is.”

Because this might seem overly harsh, I’m putting my final paragraph at the top and the bottom so the TLDR crowd doesn’t get the wrong idea: In the end, Sylvan made a decent part. The machining is masterfully done without any visible tool marks and with ultra smooth surfaces and tight clearances. I’m not excited about the finish wear and dings on the lockup faces, the hinge height interfering with knuckles and the fact that the hold-open detent is for shit but the rest of it is great for a gas gun. The only way you can make yourself totally unsatisfied with it is to expect too much of 7075 aluminum or to put it on a bolt action rifle.

part 1.
part 2.
part 3.
part 4.
Mid-Series Check-in.
part 5.
part 6.
Declaring the Winners

1. Doublestar ACE FSA, 2. SB Tactical BTFA, 3. Sylvan Arms FSA 4. MDT Carbine|Carbine FSA,
5. UTG/Leapers FSA, 6. XLR FSA 7. Law Tactical FSA (and clones) 8. Hera Arms

Unlike all of the others tested so far, this unit was not purchased by me for this test. It would have been but they’re perennially out of stock. I think I have a notion of why. Such being the case, this unit was loaned to me by another member of SnipersHide rather than being purchased. You gotta love those guys at The Hide. Famous for their relentless and savage dogpiles as they are for the just stunning levels of expertise available in their number. The dogpiles usually happen because someone was talking out of their ass or just being a dick. Oddly, the stunning expertise seems to get displayed frequently for the same reasons. It’s funny that those same blunt, savage, in your face people are also almost destructively generous with their time, money and toys. Case in point: Someone noticed I was unable to get an ACE, wanted to help me finish this project and wanted to see what I might have to say about the DoubleStar ACE so, they loaned me theirs. They don’t know me from Adam but they sent me over a hundred bucks worth of goodie without a blink. I’d do the same. It’s a culture of gentlemen over at The Hide and so it’s highly intolerant of ungentlemanly conduct. Generosity is also a characteristic of gentlemen and you’ll find that there too but, in smaller quantities. Enough about the blasted forum and its population. We have goodies to review.

There’s a lot of choice in building your ACE folding stock adapter. In a way, too much choice. DoubleStar offers an aluminum unit and a steel unit and a partially-steel push-button unit and an entirely steel non-push-button unit. They also offer lugged and un-lugged versions. They have gobs of receiver blocks to sift through and there’s some overlap in application suitability. My advice, either use the recipe below or call them to help pick what you need. It’s important to know also that their use of aluminum varies between 6061 and 7075. The pushbutton units use 6061 for the generally unstressed parts and 1018 mild steel for the stressed parts. The non-steel units are 7075 aluminum and the steel non-push-button units are pure 1018 mild steel. I told you it was an embarrassment of choice. One thing to note is, given the strength of 7075 aluminum, you’d be hard pressed to need steel in its place.

I had fully planned on going pure steel and lugged because I’m brutal on my equipment. I’m the kind of guy that would happily fold my stock, hang the rifle from a 10ft tall brick wall by the folded butt stock and then climb up that bastard if I felt the need to be on the other side of the wall. That being the case it’s helpful to pick gear that will survive my attempts to destroy it. Imagine my joy to see that my benefactor in this case chose the same way. He’ll be happy too because I was not able to damage it in my testing, though I did not actually use the rifle as a ladder out of courtesy to him.

You remember back in Part 2 where I remarked about the UTG unit, “If someone were really smart they’d take this design and make it out of steel…”? Well, it’s not literally what appears to have happened but you can see how someone might spot a thematic resemblance. It’s the details that shine brilliant light on the differences and show that whatever resemblance there is between the two units, it is superficial in the extreme.

You an see the locking block poking out of the bottom, engaging with the folding arm. The locking bar and swing arm are both steel on the push-button model. The folding arm has a receiver notch to accept the locking bar so it engages on 3 faces.

Both UTG and DoubleStar make their units square shaped. Both use quite huge locking blocks. Both have extremely positive locking in the open position. That’s pretty much where all that similarity shit stops. The DoubleStar unit is clever in places; but not very clever, and they are clever with precision. The UTG unit’s design uses cleverness to avoid the need for precision. Don’t get it twisted, the DoubleStar unit’s clever parts are nothing like the really super clever bits of the MDT and XLR units but pretty darned close and a damned sight more clever than the UTG unit. Both units took extremely straightforward approaches to the hinge and the locking blocks but the DS requires precise machining due to 90deg angles in the lockup notch and locking bar, while the UTG design actually eschews that requirement by using tapered locking surfaces which are vastly more likely to gall. When you look at each detail and compare the two you get the sense that a Russian engineer did the UTG and an American Engineer did the DoubleStar. It’s the same kind of differences as between the AR-15 and the AK-47. They both do the same job but with different mindsets. An illiterate Russian farm boy would find the UTG version fit their philosophy and an illiterate American farm boy would find the DoubleStar fit their own.

A DoubleStarUSA lugged Pig Nose. Attaches to the butt stock and the swing arm.

DoubleStar’s unit is actually the most compact lengthwise of any unit tested so far. It’s only about 1/2-inch of length of pull being added, unlike the inch to 1.5 inches of the others. The locking mechanism is well shielded from gunk and dirt infiltration while in the closed position unlike the UTG which has it’s lockup area fully exposed. While we’re on the topic of the locking mechanism. Jeebus! Talk about over-strong. Both the UTG and the DS are over-strong but the DS is way way over-strong. When you look at the barrel on a Desert Eagle you get the same sensation of, “oh, that’s quite a bit beefier than it probably needs to be” as you do when you see the locking block of the ACE and the notch into which it fits. In the closed position you could probably drive a truck over it and not do too much damage. In the open position, there’s substantially less of the locking block engaged but it’s still enough that you’d be hard pressed to break it without the use of tools.

A nifty feature of the way the buffer tube adapters connect to the ACE folder itself is, you can raise or lower each end independently of the FSA itself. This means you can raise both ends thus effectively putting the folder as low as it can get and this really helps keep the knuckle banging while operating the bolt to a minimum. It looks to me like there’s more than enough material there that they could scallop or just bevel the hell out of the top corner opposite the hinge and knuckles everywhere would sing songs of praise. At least the corners are all radius-ed enough that when you do drag a knuckle over it quickly, it doesn’t take any skin off. Still, if this was my own unit I’d already be at the grinder buzzing that corner down a bit.

A DoubleStarUSA AR-15 receiver block. Works with fixed or carbine stocks, just pull off the fixed plate if you don’t need it. Attaches to the FSA body and the chassis.

Now you might not have gathered so far but, installation is actually the easiest of any unit because you can set up each piece individually so getting things clocked is a total non-issue. True it’s only marginally easier than something like the XLR unit (which was eye-poppingly easy to install) but little things matter and a little frustration, to me, is a high cost so I appreciate the simplicity of setup. There’s more steps because there’s more parts to join up but it’s easier than the others in the end. Only the XLR is actually anything near “as” easy. The Hera unit was close but the allen key size needed on the chassis end is smaller than it should be to properly torque things down.

The other place where this unit just crushes the superficially similar UTG unit is the push button unlock. It’s not super obtrusive, you barely notice it there at all until you want to fold or unfold the thing. Then it’s a firm but not hard press and the thing smoothly unlocks with absolutely no drama nor even any blood blisters. The way the UTG works, you could end up waving your rifle around pretty irresponsibly while trying to unlock it.

So with all of this going for the DoubleStar ACE, what’s the downside if any? It’s heavy as balls compared to all of the others except the Law Tactical unit. Easily twice the weight which ought not surprise anyone since steel is more than twice as heavy per unit volume as aluminum. That’s about it. Oh yeah, and as alluded to earlier the number of attachment options and materials options and other options for how you put it together can easily get confusing when trying to pick the 3 pieces you’ll need from their website. That’s all the negative I can find.

To make your life easier, if you want one like the unit being evaluated here then you want a FSM-PB folding mechanism with boss ($69.99) + a CAR-15 Stock Adatper (aka Pig Nose) with boss ($29.99), and an AR-15 receiver block ($32.99). That comes in at about $130 and then add shipping and you’re probably at $150 all in which makes this very much competitive on price with the MDT and Sylvan units but with the critical parts of the folding and locking bits made of steel.

Still, the confusion-enabling profusion of choice there cost it a point for coming with everything needed to install. You can easily fail to buy the right thing and since you make your own kit, so to speak, you’re at the mercy of your own silliness and bad judgement. DoubleStarUSA tries to be helpful about telling you what bits go with what other bits but the information is scattered so it’s hard to make sense of until you’ve spent more time than necessary doubting if you got it right. Being men, we stereotypically just won’t call and ask for help normally (though I did many weeks ago for the sake of this article).

How about wiggle and instructions and other factors that make points differences? As far as wiggle, just the tiniest amount of it which you can’t tell while using it and it’s only in the mating of the lockup surfaces, not the joint or anything else. The way the locking block works, I’m not sure how I’d go about trying to bring that tolerance to zero. That being the case, it lost one of 3 points it could have gotten for the tightness of the lockup. Instructions were not included with the loaner (at this point I don’t need them) but it’d be pretty hard to fuck up the installation even if you just gut-feel the install procedure. Still, I’m taking the 2 points for clear instructions because just picking the pieces can daunt some people. They really need to make a “precision rifle package” with those 3 bits in it so we can turn our brains off while we shop, like women seem to get to do.

After all is said and done, the DoubleStar ACE with push button release, lugged pig nose and receiver block pulled down an impressive 16 of 19 points, putting it in 4th place overall so far on value (points divided by cost) and just barely trailing the 3rd place entry. This sits right up there in quality/features/value with the offerings from MDT, Hera Arms and XLR Industries which were all beyond excellent. I’m tempted to give an extra point for the ability to independently adjust up/down the relationship of the folder to both the chassis and the buffer tube and for the unthinkable robustness of the lockup parts. That’s all really slick. However, in fairness, I didn’t give any special treatment to any other so far so I’m not going to start now. The only thing that stops it getting 5 stars in the arbitrary rating scale is the 90 degree corner that’s still just a little in the way of my fat fingers wrapped around my oversized bolt handle.

What is not in the way is the push button. It’s underneath the stock if you set it up for left side folding. If you set it up for right side folding, there could be bolt travel interference issues. I didn’t have any interference folding either way using an LSS stock on either a Mossberg MVP or a Savage 10. Long actions may be different. Keep in mind that only matters for lefties though and only if they want the stock and bolt handle on opposite sides when it’s all folded up.

What can we learn from what we’ve gathered so far? Easy. Steel rules the damned roost. You can have a super slick design but if you make it from crap materials (China, we’re looking at you) you’ve only made a very slick piece of shit. You can take a totally non-clever thing and if you make it from good materials and make it well with tight tolerances, you’ve made a very un-clever but high quality and therefore probably useful thing. You can also make a very un-clever thing out of shit materials so long as the design is optimized for shit materials (looking at you, UTG) you’ll still have a useful widget. For me, as much as I really like this DoubleStar ACE push-button unit I think for me the XLR, MDT and Hera units are a better fit just because of the physical shape allowing them to not interfere at all with my knuckles.

part 1.
part 2.
part 3.
part 4.
Mid-Series Check-in.
part 5.
part 6.
Declaring the Winners

1. Doublestar Ace FSA, 2. SB Tactical BTFA, 3. Sylvan Arms FSA 4. MDT Carbine|Carbine FSA,
5. UTG/Leapers FSA, 6. XLR FSA 7. Law Tactical FSA (and clones) 8. Hera Arms SFU

Now that we’re halfway through this expedition we can start reporting some details. Once you have the chance to install, uninstall, adjust and use several very different FSA’s you start building up an intuition about how various units will end up. There are surprises though. Big ones. So let’s jump in and analyze the obtainium units and we’ll come back to the unobtainium units when we finally manage to obtain them.

What you’re all looking for is going to be basically a quantification of value and an assessment of what the worst points are. The best points are all going to be the same… They all fold, after all, which is their job so it better be that folding is their best point. Ok, cool then we just have to look for glaring differences in how they fold and then look for their worst points. So we need to set up a scoring system but the problem with those are, linear numeric scoring systems usually hide the most important pieces of information inside less helpful information. Linear scales are great for comparing single variable differences. Logarithmic scales are great for comparing exponential trends. 3d graphing helps make more sense of things but it requires that there be certain relationships between the pieces of data being analyzed. Using a single chart for subjective and objective trend lines is, if anything, misleading at best. That being the case, here there has to be both a subjective winner and an objective winner and they’re both genuinely winners but they’re winners to different people.

The Hera Arms and XLR Industries units are super compact.

The subjective winner isn’t looking to subtlety to create value but rather is looking with a more Soviet sort of mindset, “Winner is thing cheapest to make while strong enough for illiterate farm boy to not destroy by accident.” The objetive winner comes from the mindset of, “A Timex is a watch. A Rolex is a good watch.” People buying Rolex are looking for refinement. People buying a Timex are not. To the casual eye though, there’s no difference between the two.

So below you’ll find rankings based on the point of view of Rolex buyers in the number of stars awarded and you’ll find rankings based on the point of view of Timex buyers in the value ranking. If budget is your first concern and your budget is TINY (the caps is ironic isn’t it), then “value” is your best measuring stick. If not, then use the star count.

“Value” is calculated by dividing the points achieved by the dollar cost. What this does is give us a benefit per cost unit. We can see that using this simple numerical scale and an unsophisticated view that the UTG unit would come out on top by about 7x. For budget minded people it could but still, it was given only 2 stars. So a Rolex buyer should look at the star count and a Timex buyer should look at the value count. Nobody should look to the points count alone.

The stars are entirely subjective and have no formula or equation backing them up. They’re arbitrarily scored in the way that a Rolex buyer would compare 2 Rolex watches. It’s just what the tester thinks of the unit so you’re beholden to my judgement there. The UTG is fine and workable but it’s still kinda shitty to use compared to the others so the subjective view gives it a very low score.

The above seems like it’s speaking out of both sides of the mouth, there’s a reason for that. It kinda is exactly like that. Why? There’s no mathematical way of eliminating the UTG unit from the winner’s circle but the winner’s circle is doomed to be inhabited by others providing vastly better function/design/features/materials, except to do so subjectively which is to say “arbitrarily”. UTG’s part is 100% functional and the price point is so low while the unit is good enough for the whole thing to be an insult to common sense.

So UTG, even though you’re the clear winner by a mile based on pure quantitative criteria, you’re still at the shit end of the stick and you come in in the bottom half because your part is so horrible to install and literally painful to use.

So now that we’ve covered the part where I come clean about some arbitrariness in the scoring system, we can continue unabated and unabashed. UTG can be happy knowing that they won and only some Pennsylvania-style tinkering with the ballots managed to allow a costlier solution to win.

The XLR unit is fantastic in every way. All the stuff you want is there and it costs less than most of the others. Every feature is done nicely and it’s really compact. Directions came with it and it’s clear that they put a lot of thought into the design. It’s got all the features and it’s very small and really well priced. You’d be hard pressed to do any better. Installation is made terribly easy to not fuck up. Materials selection is spot on given the amount of wear we’re not seeing even after a couple matches.

The MDT unit is almost as kickass as the XLR and would have done better but for the $50 extra for any kind of open-locking function and one bugaboo about the install. Lockup was the tightest of any unit we tried and is impressive but looking deeper at how that is accomplished (interference fit) one can’t help but wonder when those tolerances will open up enough to let wobble happen. Time will tell. It could be a long time and based on the wear seen so far, it’ll take a long time to find out. Having instructions in the box that say “go online for instructions” is glib, a shitty waste of an instruction card and a stupid way to piss people off. Just print them on the card you’re already including for God’s sake. The MDT was among the more costly units which goes with MDT’s practice of not leaving any dollars on the table. Their shipping was super fast and their order fulfillment system’s communication setup is fantastic.

The UTG/Leapers unit was everything and nothing. It’s got all the features fully implemented but somehow it still ended up being a hateful little bitch that punished me for liking it, kinda like a super hot lesbian that habitually cock-teases straight guys. Where it completely destroys the competition is on price divided by quality+features. NOBODY could compete there. If your budget is so constricted that this is how you’re planning on going I can only encourage you to save up some more but if you don’t, you’re not really losing much except blood blisters. If you can’t or won’t pop for a higher end unit then at least know that you’ve got the absolute most that you possibly could in any universe for your $15 plus shipping.

If anyone gives you shit, tell them I said to shut up and then tell them the price and then tell them that the price doesn’t even reflect the value, which is miles higher than the price suggests. Honestly if they charge $60 for it and the Chinese scammers charged $15 for their Law clone, that would really make sense of the whole tangled mess and we could all go back to “you get what you pay for” and comparisons like this one would become redundant WOMBATs (waste of money, brains and time).

The Hera Arms unit is what you’d expect for a first version of XLR’s current offering if you came across their V2 unit first. It’s extremely well made, well thought out and also comparatively inexpensive (you can get them for under $90 plus shipping and tax which comes out to $119). Where it falls short of MDT or XLR’s current offerings isn’t in any way that’ll bother anyone or affect a shot and it’s a little smaller than those other 2 so there’s that. The place it’s not as good is lockup. It needed a strip of masking tape to bring it to zero lash. That said, I could not detect the lash from behind the gun to begin with. If XLR bumped their price ten bucks and UTG and China adjusted their prices as discussed above, then the pricing tiers for all tested units so far would make intuitive sense.

Sylvan Arms unit is essentially a 7075 aluminum version of the Law Tactical unit and as soon as it shows up, we’ll test it. I was a little dubious because it’s a gas gun unit but I’ll put it on my AR-15 when we’re all done here and since that’ll piss off all the politicians in the state, I’ll call that the value add I need. One thing that is very different between the Sylvan and the Law is that the Law can actually be fired exactly 1 time while open (in an emergency) without the bolt carrier coming back and saying hi to your face. Granted doing so will bend the little tab that retains the bolt carrier & extension while in the folded position and you’ll have to replace that catch before the gun will work again but it is an emergency capability not provided by Sylvan’s unit. Do that shoot-while-open with the Sylvan unit and you might just be eating bolt carrier for dinner. Other differences are more subtle. The Law Tactical unit has it’s little push button gated so as to avoid inadvertent activation. Sylvan doesn’t have that. The Sylvan reported also has some issues staying open because the ball detent groove isn’t fat enough for them to sit deep enough to provide sufficient resistance to opening.

Our DoubleStar and Sylvan units are due to arrive in mere days and we’ll get back after it as soon as they do. The only remaining units to look at are the SB-Tactical and the Dead Foot Arms. SB-Tactical may never be evaluated if we can never get hold of one. Dead Foot’s offering is really quite AR-15 specific and ludicrously expensive compared to all the others so we may or may not test it. It would be nice but would probably run afoul of California assault weapons laws. We’ll have to consult with Legal before ordering that.

part 1.
part 2.
part 3.
part 4.
Mid-Series Check-in.
part 5.
part 6.
Declaring the Winners

1.2. 3. 4.
5. 6. 7. 8.

1. Doublestar Ace FSA, 2. SB Tactical BTFA, 3. Sylvan Arms FSA 4. MDT Carbine|Carbine FSA,
5. UTG/Leapers FSA, 6. XLR FSA 7. Law Tactical FSA (and clones) 8. Hera Arms

Ordered on November 15th from https://ballisticdeals.com. It shipped on November 18th and I got email notifications of order and shipment. It arrived on November 23rd and I immediately pulled it out to do some testing. Finish is fantastic, fit is perfect save a tiny bit of play in one direction.

It’s extremely nice and super compact. Obviously made to that quintessentially Teutonic standard which borders on the manufacturing equivalent of pedantry. Germans just make things well. It’s in their DNA.

It would have been nice if the design didn’t need a snugging up mechanism like the MDT design but, alas, the Hera unit doesn’t come with a snugging up mechanism which cost it a point. Still, ever the optimist, I applied 1 layer of masking tape on the flat mating surfaces and that brought all the wiggle to zero and the sound of it closing took on the thud of a bank vault. It wouldn’t have been enough wiggle to notice behind the gun. Interesting note, when XLR Industries later licensed the design they added two set screws that you could back out to snug the thing up. I’ll forgive it in my heart but still deduct the point and I’ll end up adding those set screws because they just make sense even if a layer of masking tape does just as well.

So far the Hera Arms unit is the most compact by a good ways.
There’s just nothing else to cut off.

It has a decent ball detent does an ok hold-open job for extremely light butt stocks but if your butt is made of metal, it’s probably not going to hold it open against a shake. It will probably not keep the thing from banging you in the head during a hike with the rifle backpack stowed. Even if it’s not super functional it counts as a two way locking design. (NOTE: I’m using “locking” very loosely during this whole thing for fairness.) Manufacturing quality is very nice. No machining marks, nice anodized finish, no dings. Install is as easy as with the XLR unit and pretty much identical though the Hera uses a much smaller allen key for the chassis interface snug-up which I found to be not confidence inspiring. XLR later improved the design and their version uses a MUCH larger allen key which is confidence inspiring. To install, spin the adapter onto your chassis, clock it, snug the hell out of the 2 locking screws, install butt, clock the butt, snug the castle nut.

Did we mention that it’s super compact too? Upside all other units is visibly the smallest by a good ways. The XLR and MDT units are not a lot bigger but they are a bit bigger. Why does side matter for this? It’s mostly a matter of clearance for your bolt cycling hand. Some of these units I’ve tested (UTG/Leapers, looking your direction) stick out in places that hands will eventually be cycling bolts in. Drag your knuckle at high speed across a folding stock adapter and I bet you’ll howl. So, it matters about size and it matters about where that size is concentrated.

Here’s a little trivia for you: Dark Rey’s light saber actually uses a real Hera Arms SFU as its folding mechanism in whatever Star Something movie has a character named “Dark Rey” whom also uses a thing called a “light saber”. It’s true. I looked it up and there are even pictures of it on the movie prop. Cool huh? You can see in the image below the distinctive locking hasp and overall profile and above you can see the actual unit used on the actual light saber from the movie complete with the Hera sticker. Yeah, Hera doesn’t engrave, the use a small sticker. Classy.

This unit, like most of them being tested is not compatible with any AR-15 where the bolt carrier reciprocates through the buffer tube/upper interface. For a bolt action rifle though it’s awesome. Slim, sleek, well made, tough and relatively inexpensive but with all the features one might want and it installs as easily as a child’s finger goes into his nose.

Where did it fall down? No instructions in the box or generally available to a quick Google search and the small size of allen key used to install it. Honestly if you need instructions though, you should not have tools or guns or hands and any of those will just get you into trouble. The rest of us already assume that you’re mechanically inept enough to destroy the Earth with an extravagant gesture. If a small allen key is a stopper for you, then I’ll assume you don’t own anything electronic that ever needs batteries installed. For everyone else, it’s trivially easy to overlook Hera losing 2 points there on the no instructions thing.

It picked up some point value for the steel locking mechanism, lost some for 6061 aluminum body and balanced out at .75 for construction. It lost another full point for no tuning mechanism for the wiggle (though a strip of masking tape works wonders) and for there being wiggle when the bipod is unloaded. It got full pretty much points otherwise and looks like it’ll probably end up winning for compactness unless the SB Tactical unit is insanely compact. The total score of 14.75 out of 19 places it in a solid 3rd place so far.

part 1.
part 2.
part 3.
part 4.
Mid-Series Check-in.
part 5.
part 6.
Declaring the Winners