How much .22LR case bulge is normal for an AR?

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BenFoo

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Was shooting my 22LR dedicated AR today and I had a case blow out the side. After clearing, I shot two more rounds just to make sure everything was functioning. I picked up the other cases and noticed they were bulged. I went back to another spot I was shooting earlier and noticed those were bulged too.

Upper: Chiappa 22LR upper
Ammo: CCI mini-mags 40g and Aguila Interceptor 40g. Both considered high velocity 22.

Pics:
Side blown out.
y8abape4.jpg

Case bulge. Seems to be the worst where the extractor cut out is.
4ebyby6y.jpg


Just to check the ammo I fired a few out of a Rem 12A. They looked fine.
upugagu4.jpg


Thoughts? Something wrong?
 
How much .22LR case bulge is normal for an AR?
Click to expand...
None.
All your empties should look just like the ones out of your other rifle.
Just because it's an AR doesn't nullify all known safety rules.

Something is very wrong.

Your AR bolt is not staying closed long enough for pressure to drop and extraction to happen normally.

Weak recoil spring?
Or you left out a heavy buffer or something that came with the kit to add mass to the blow-back bolt??

Whatever it is, it isn't right.
Cease & desist shooting it till you get it figured out & fixed.

And if you ever run into bulged cases like that in any firearm again?
STOP SHOOTING right there, after you see the first one!!

rc
 
Yah. That is what I thought. I read a few other threads/posts (on other forums) that this was "normal" for 22 ARs and it didnt make much sense.

Thanks for the sanity check guys.

Time to pull the rifle a part and see if I can find anything. If not I guess its going back to the manu.
 
Returned mine about a year ago

Bought one from a local dealer and it did EXACTLY the same as yours.

Tried a few different makers and all did the same,took it back and he and I went out back of his place and tried mine and then another one he had in shop .

BOTH took a poop and he sent them back and the company said that it was a known problem and they did not sell him any more uppers.

I took the refund and got a GSG/HK wanna be in .22 that is a hoot and shoots just fine.

btw - I shot an S&W M&P .22 and they are VERY accurate.

So bought one and am not interested in another upper.
 
Upper: Chiappa 22LR upper
Click to expand...
If not I guess its going back to the manu.
Click to expand...

I hope they have more competence with your AR 22 upper than they did with the "repair" of my 1911-22.

Good luck!


The blown rim sometimes just happens with .22lr, although it should be quite rare, it wasn't with the Remington "Golden Bullet" bulk pack, which was the final straw that made me quit buying it, but all the bulged cases are most definitely indicative of something very wrong!
 
If you got a CMMG dedicated 22LR upper, you should not have any issues like that. Not even with accuracy. Based on your case bulge, I'd check your recoil/buffer system. The other thing to check is your forward assist and bolt. I have the CMMG, too and the forward assist was really tight and that impacted the bolt's movement until it worn in.
 
I have a spikes conversion kit that does that when it gets dirty. My problem is it will fire slightly oit of battery, so I have to keep it clean and lubed. You should be able to see if the bolt fully closes, it might be your problem.
 
My first guess is that the bolt/carrier mass is too low. Bolt opens while. Pressure is too high and the cartridge brass can't handle the pressure.

Buffer spring rate doesn't really figure into it, although half the spring's weight should be counted as recoiling mass.

I'd try adding some weight to the buffer or bolt carrier first. Or send it back to the manufacturer.

BSW
 
wally said:
I hope they have more competence with your AR 22 upper than they did with the "repair" of my 1911-22.

Good luck!


The blown rim sometimes just happens with .22lr, although it should be quite rare, it wasn't with the Remington "Golden Bullet" bulk pack, which was the final straw that made me quit buying it, but all the bulged cases are most definitely indicative of something very wrong!
Click to expand...

Yah i had some strange issues with the Rem Goldens as well. I chalked it ip to the ammo. Apparently there was another player....my upper.
 
firesky101 said:
I have a spikes conversion kit that does that when it gets dirty. My problem is it will fire slightly oit of battery, so I have to keep it clean and lubed. You should be able to see if the bolt fully closes, it might be your problem.
Click to expand...

It was freshly cleaned before this time out. Normally when this one starts getting dirty it starts having FTFs because the bolt doesn't fully close.
 
My theory is that the bolt is opening before it should. I contacted Chiappa via their online contact form (ick) we'll see what happens.
 
I have a dedicated CMMG .22lr upper and had a very similar casing to that not too long ago. I had put thousands of rounds through it before it happened one day at the range. After it happened, I broke everything down and inspected it. Not seeing any damage, I loaded a magazine and fired away with no problems since. Mine seems to be a one time deal while yours seems to be a recurring issue. It does concern me though.
 
the bolt is opening before it should
Click to expand...
I don't think so, unless this upper has a locking bolt system that i'm unaware of. If it's a blowback action, like every other semi auto .22lr i've seen, the only thing keeping the bolt forward is the recoil spring...which you can test by using a trigger pull scale or a small pocket fishing scale, and compare the # against another semi-.22's spring tension. Basic physics (action/reaction) would imply that the bolt will only start opening when the bullet is moving in the opposite direction...and since the powder's already gone off at that point, the case would have bulged too...but it can't, if it is supported. So it must not have been supported: implying it wasn't fully in battery to begin with.

It looks to me like the chamber is cut short, or just has some hard crud in it, that stops the casing from fully traveling into the chamber. OP didn't state if the gun was new... if it is, check chamber depth; and if it's well used, get a good brass brush...
 
Actually, the recoil spring plays a very small part in keeping a blow-back bolt shut while pressure drops.

Bolt mass, or inertia is what keeps it shut.

The recoil spring is in a mostly relaxed state when the bolt is closed.

It is only compressed and delivering full power when the bolt is back.
Then the stored energy is used to return the bolt and feed the next round.

rc
 
Basic physics (action/reaction) would imply that the bolt will only start opening when the bullet is moving in the opposite direction
Click to expand...

So if the barrel were blocked, right at the end of the chamber, so the bullet couldn't move at all then the bolt would stay closed? I don't think so...
 
All the bolt 'sees' is the pressure trying to push the case out of the chamber. Wither or not the bullet is moving doesn't enter into it. You're running a internal combustion engine and either 'piston' (bullet and or bolt) can move or not. The rate they move at depends on the relative mass, so in a typical blowback operated firearm the bolt moves slower than the bullet simply because the bolt is heavier. If they were they same weight, they would move at the same velocity in opposite directions.

BSW
 
While I cant be certain that its always done it, I'm pretty sure. I did find some brass I picked up awhile ago and forgot I had.

These are Rem Goldens at about 200-300rds total on the gun.
rysu5une.jpg
 
I have a CMMG conversion kit and after about 700 rounds of mixed Federal Bulk and Rem GB it started to do this. After a good cleaning all was well.

I have a feeling that these kits will fire out of battery just because of the loose tolerances. Once the bolt face, chamber, or some other part starts to get gunked up then the bolt does not fully close and this is what you get.
 
Have you ever shot any of the Aquila 60 grain SSS ammo in this rifle?

I ask because this looks like just the sort of out of battery damage one can get in some of the older .22 s,l,lr semi autos if one shoots shorts for a bit then switches back to LR.

The Aquila SSS does have the overall length of a LR but actually uses a short case.

You have said you cleaned this rifle and still had the bulges....how did you clean it? What did you clean it with.

As others have pointed out this REALLY looks like the gun is firing out of battery.

This can be from the cartridge not fully seating in the chamber OR from the bolt not being fully forward because of an extractor or ejector problem that allows a head space problem so the case initially flys back unsupported then smacks the bolt face and has that ring unsupported formed basically by swaging.

Seriously the blown case and bulged cases are exactly like those I got as a kid after using an old Model 6 with LR after I had been feeding it shorts for a bit. Cleaning the chamber from the breech end with a new bronze brush by inserting it and turning it one way then a new brush and turning the others with Hoppes or RBC (old GI Rifle Bore Cleaner) and then finishing with the very tight white patch until absolutely clean cured my old Savages problems

Make sure the ejector has nothing under it or under the back of it that is preventing it from snapping over the rim. Make sure the breech face is clean right to the edge of the breech face.

Now you at least know why we all insist on safety glasses.........

-kBob
 
Looks like the bolt is not fully closed: It is closed enough to fire, but not closed enough to contain the pressure.
=>
Dirty chamber or bad job of chambering a round.

Probably you are just better off with a different upper.
 
Cleaning consists of Hoppes#9, brass and plastic breach and barrel brushes and wet and dry pads.

Oiling is with Hoppes TEK3 oil.

The BCG is a PITA to disassemble to cleaning. Gotta use the punch and hammer.
 
I had a similar problem with my Chiappa 1911-22 .22LR pistol. The chamber was defective and the barrel liner (which on that model contains the chamber) needed to be replaced.
 
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