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Discussion Starter · #1 ·
I'm hoping someone with one will step up - it's not a common gun, asking on my usual forum was a flop...

I think mine has a loose chamber. Generally wasn't a problem before (but this is not a gun one shoots often so it's not like I had a lot of rounds through it and I haven't shot factory ammo before either...) but a friend asked to play with it recently so I took it out to shoot...

S&B factory ammo (that he brought, that's what good people that want to try out a gun do :p), FTF on second round, primer had a firing pin imprint on it... he finished the magazine and I wanted to see if the FTF round would fire, I put a few more rounds in the mag and the FTF round on top... let the slide go forward... pull the trigger - nothing, wait the few seconds, repeat... well, it fired after a few tries... didn't feel any different except the casing didn't eject... and the primer was gone... and there were some serious signs of overpressure... (case head smooshed)

Well... time for some pictures to tell the tale and why I think there is a problem with the chamber that I never noticed before...

Put a rod in the barrel and hammer out the casing... except a part of the casing is still in there... (case head separation alright)



Ok, let's see if I can extract the rest of it carefullly with my field expedient broken case extractor aka a tap - worked well



Except is that the rest of the bullet jacket still there? Look carefully at the mouth of the case, zoom in...



Yup (after taking the tap out) - and the remnants of the primer... that were somehow in the case...



I'm thoroughly impressed with how strong the gun is - no signs of damage whatsoever... I'm very lucky - things could have gone much worse, I know. But none of my past experience led me to expect anything of this sort... But how could this happen? By the looks of the case mouth, could it be jammed past where it's supposed to be in the chamber?

Ok, let's try some plunk tests with this ammo. Most of the time it looks just fine:



But occasionally



This shouldn't happen, right? Just on the off chance I pulled out the carbine - nope, can't do that.



So... here's what I think happened.

Cartridge gets picked up from the mag, but instead of the extractor jumping over the rim it pushes it into the chamber because the chamber is just too big, huge out of spec headspace results. 30carb headspaces on the case mouth, right? And in this case (ha!) the cartridge got pushed past that point...
FTF, of course, because the firing pin doesn't quite reach the primer. At this time the bullet is jammed into the rifling - you can see marks on the jacket that got left behind.
I keep cocking the hammer and trying to fire until eventually the primer has enough abuse and goes...
Out of spec headspace + bullet in the rifling - overpressure. The primer is blown, the case is torn in half as it's pushed back to the boltface, but the bullet is still jammed in the rifling so the core gets blown forward with most of the jacket...

If this were a new gun, I'd call this a warranty issue, but for lack of an ouija board, AMT is quite out of reach for any claims :) Anyone with an automag III, could you try the plunk test in yours and see if you have the same issue? If you have factory S&B please use that - i.e. did they just ream all chambers generously and I never saw this before with reloaded ammo? Or is S&B generally small? I can only replicate this with the S&B factory, not with my reloads from a Lee die... I don't have a headspace gauge...

Does anyone know where I can get a spare barrel? :)
 

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I would certainly have a good gunsmith take a look at that gun before I shot it anymore. You might also mic the ammo. It could be that the ammo has a little crimp on it that lets it go too far into the chamber. Good luck and glad it wasn’t worse !
 

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Discussion Starter · #3 ·
I've never shot anything but my own reloads in it... I asked around and was able to get some old surplus...

So what do you know! No problems whatsoever, and when I measure at the mouth (Mitutoyo dial caliper - quality ;) )

S&B is smaller by .004" compared to surplus. Ouch! (.334 being max spec, I believe, .332 on surplus and .328 on S&B)

So fair warning, NOT ALL FACTORY ammo is SAFE in these pistols!!!



 
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