Found – The Casing From the Shot That Belled My Glock 21 Barrel

Funny story in places. Sad in others. Stupid in some. We’ll start with picture time and then move on to story time. I’m sure that’s how you all would prefer it.
Juicy primer flattening + primer flow into the firing pin / striker channel. Doesn’t look so bad right?
Who’s got a big Buddha belly? Oh yes. You’ve got a big Buddha belly.
Coach decided to crank out a few thousand .45ACP loads after our last casting party. Fine enough. So he goes to work and cranks out 4K rounds. His .45’s have been very uniform and 100% reliable, if a little smoky. When we shoot pistols we’ll usually go through 1-2k rounds in a day between us. Coach failed to notice 1 critically important thing while loading. Occasionally the powder charge bar on the Dillon 550 would fail to return to battery to pick up another charge. That could have been sorted out by weighing finished rounds except that we’re using lubricated cast bullets and mixed brass.
A month or two goes by and we make it out to the range and do some combat oriented drills which means rapid fire and double taps are the norm. So we’re shooting, we’re shooting, we run out of ammo after draining a full .50cal ammo can of .45ACP and then we go home. After a day or so I pull out my Glock G21 from the safe to give it a thorough swabbing out and notice a black ring in my bore just in front of the chamber during a visual inspection.
I thought it might be a lead ring since I’m shooting cast lead in a Glock barrel or a carbon ring due to the extreme dirtiness of our loads but it didn’t come out after a vigorous brush cleaning or even show signs of change. Then I punched a patch down the barrel and it went in snug in the chamber tight in the throat, hotdog in a hallway just after the throat about where that black ring was, and tight as a drum the rest of the way. Then I looked at my barrel’s exterior more closely. It was belled about 1/2″ in front of the chamber for about 1/4″ of distance and just severely enough to be barely visible to the naked eye (about .030 diametric difference).
Ok, well, I figured it’d happen sooner or later shooting cast bullets from a factory glock barrel. So I bought a new aftermarket barrel with conventional rifling that would be ok with long term use of cast lead. I also shot another 500 rounds through the old damaged glock barrel while waiting for the new one to arrive. It worked just fine. I knew it would because there’s no saying that the round that belled the barrel was the last one I shot.
What happened? Well, a week or 2 ago I got a call from Coach and he’s going on and on about having found “the case”. I’m like, “What case?” and he fills me in that he’s 100% certain that THIS case is the one that was fired when my barrel was damaged. I was skeptical. How did you pick that one out of the 2000+ that we’d recently emptied?
Well, it was pretty easy and it actually tells us a neat story that goes like this:
1. Coach loads his 1911 with ammo.
2. Coach fires some shots and gets a fail to fire and ejects a loaded round onto the ground and walks back to the mag loading area.
3. I load my Glock with ammo, walk to the firing line and shoot most of my mag but the last round fails to fire so I eject it. I then notice what I think is my round on the ground with a bullet in the case and figure, “Oh, last one didn’t go off, maybe a light primer strike or shallow seated primer. One more tap on the cap and it might just fire.” and so I pick up the round and drop it into my Glock, slam the slide home & pull the trigger it goes bang.
4. I load another mag and keep shooting.
What happened was when Coach hit the primer on that round it was probably shallow seated and finished seating with coach’s hammer fall but didn’t go off and coach flopped it onto the ground and walked away. I went to the same spot Coach was at to shoot and when I got a click-no-bang and then saw a loaded round on the ground and assumed it was mine and stuffed it into my gun, I failed entirely to realize that there might be a bullet stuck some distance down my bore or to have noticed the empty case I ejected earlier being empty despite no bang happening. That should have made it clear to me but I was a fool.
When I picked up that fateful round and fired it the bullet left the case mouth’s grip and entered the bore only to slam into the back end of the previous bullet. The air trapped between them became an incompressable fluid and when pressure was sufficient it belled my barrel before both bullets took the opportunity to leave the muzzle. My mag didn’t blow out, I didn’t notice any real recoil change, the gun kept working.
I’ve had a case blow in this gun before. That was from repeated loading with stout loads. This one was from multiple levels of bad idea compounding each other. I’m just surprised the barrel didn’t go full banana and cause a catastrophic self-disassembly of the entire pistol.
The 2 primer hits on the brass and the bit that flowed into the striker channel being rectangular while there was also a round firing pin strike is a dead giveaway for a double primer strike. Note to self. If the ammo is on the ground, leave it on the ground.
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