Folding Stock Adapter Comparison Mid-Series Check-In


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.

Brand Model Ordered Received Price Vendor Points Value Stars
DoubleStar USA Steel folder w/ lug
AR-15 Receiver block
Loaner Shipped   $130 DoubleStarUSA 16 .12 *****
SB Tactical Buffer Tube Folding Adapter Backorder            
Sylvan Arms Folding Stock Adapter 12/6 12/12 $180 Primary Arms      
MDT Folding Stock Adapter
carbine/carbine interface
11/10 11/13 $149 mdttac.com 16.75 .11 ***
UTG/Leapers AK-47 Side Folding Stock Adapter 10/31 11/9 $15 leapers.com 10.5 .7 **
XLR Industries Folding Stock Adapter 10/31 11/5 $115 XLRindustries.com 18.5 .16 ****
Law Tactical Folding Stock Adapter On Hand On Hand $239 Law Tactical 19 .07 *****
Hera Arms Side Folding Unit 11/15 11/23 $119 Ballisticdeals.com 14.75 .13 ***
Facebook/China Folding Stock Adapter 9/5 10/24 $58 China 2.4 .04 *

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.

XLR Instudtries. The center screw pulls the wiggle out. The top & bottom screws lock it to the chassis.

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.

Despite having no system to adjust lockup, MDT’s offering had the most solid lockup out of the box.

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.

Mmmmm. Blood blister machine.

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 compactness of the Hera Arms unit is a big feature. Perfect for slender guns wearing MDT stocks.

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 is a Law clone so we’re holding it to the same standard which it will have a hard time standing up to.

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

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