stuck case in AR-15

[PrestoColumbus]

Today I went to test the fps on some hand loads. Starting with the min load, I got 7 rounds into it and got a case stuck in my rifle and I can't pull the slide back. I took it to gunsmith, but it might be a couple days before I get it back.

What should I be looking for to prevent this from re-occurring?





I will provide some further details:

I hand-loaded 4 sets of 10 rounds of 300 AAC, 220 gr boolits, H110 powder
10 rounds with 6.7 gr powder (min charge from my load book)
10 rounds with 7.8 gr powder
10 rounds with 8.8 gr powder
10 rounds with 9.9 gr powder

Fired 6 rounds, chrono measured about 800 fps, which was what I expected based on the load book. It also didn't cycle the action completely, which I expected. After each shot I could see the bolt was partially pushed back but not far enough to eject the case and chamber a new round. Manually cycled with charging handle no problem.

On round 7 of the 6.7 gr loads, I felt the recoil, like the bolt didn't cycle into the recoil spring. Observing the rifle I saw an unusual amount of smoke coming from the rifle, around the bolt, even some black soot down into the magazine onto the other rounds. The bolt never moved. I believe all the smoke I saw normally would've rapidly escaped when the bolt cycles.

When I manually cycled the rifle after round 6 it didn't go fully into battery. I thought nothing of it at the time, and lacking a forward assist, I partially pulled back the charging handle and released it, and the bolt chambered the round fully. I don't know if that has anything to do with it. My experience is that it isn't unusual when manually cycling the rifle .

So now I can't budge the bolt. It is still fully forward. I can take the upper off the lower.

I have no idea what caused it. Did I damage the case at some point when I loaded that round? Is this "normal"?

If anyone has advice of what I can look for, what commonly causes this, and how to prevent I would greatly appreciate it.


Thank you

[Bills Shed]

Sounds like trouble.
Did you put a cleaning rod down the barrel and see if the projectile actually left the barrel?
Keep us posted

Bill

[PrestoColumbus]

yep, have a reading on the chrono as well. something kept that bolt solidly in place when the round fired

[badguybuster]

Grab the charging handle and push down while tapping the stock gently on the ground. Just do it in a safe area

[kerplode]

Grab the charging handle and push down while tapping the stock gently on the ground. Just do it in a safe area

And if it's a carbine stock, collapse it all the way forward first so you don't bugger your receiver extension detent holes.

FWIW, this is called "Mortaring". I suspect what happened is that that round didn't have enough juice, short cycled, and shoved the fired (and now expanded) case back into the chamber, sticking it. This same thing happens with FALs if you have the regulator all the way open.

In the future, when working with subs and such, start with the hotter loads, work down, and stop when they fail to cycle (or if a bullet doesn't clear the barrel, obviously)

[Gtek]

Converted brass?

[imashooter2]

…I suspect what happened is that that round didn't have enough juice, short cycled, and shoved the fired (and now expanded) case back into the chamber, sticking it. This same thing happens with FALs if you have the regulator all the way open….

That is a definite possibility, but the smoke coming around the bolt and soot in the magazine concerns me more than just a little.

[DDriller]

Take the magazine out and use a large screwdriver on the BC. Twisting the screw driver will open the action much better than trying to mortar it out.

[PrestoColumbus]

And if it's a carbine stock, collapse it all the way forward first so you don't bugger your receiver extension detent holes.

FWIW, this is called "Mortaring". I suspect what happened is that that round didn't have enough juice, short cycled, and shoved the fired (and now expanded) case back into the chamber, sticking it. This same thing happens with FALs if you have the regulator all the way open.

In the future, when working with subs and such, start with the hotter loads, work down, and stop when they fail to cycle (or if a bullet doesn't clear the barrel, obviously)

that makes sense. I started with the min load. And my FPS was 713-839. (load book was 900 fps) so my first string are definitely on the lighter side.

[popper]

Actually a small motorcycle tire removal tool works best as it has a 'hook' to the end. remove upper. Lever the BCG out on the front pin bush. H110 does NOT like to be downloaded. That's about 40% fill. Case rupture/blown primer or head swollen into the extension. May look like this.

[NC_JEFF]

Check round 6 to see if the primer blew out of the case, they like to get stuck in/under the bolt key lugs. Primers are much softer that the bolt and chamber so you can tap on the back of the bolt with a wooden dowel, using a mallet. The primer will crush, the bolt will go into full battery and can be cycled normally. Or you can mortar the thing until the bolt unlocks

[PrestoColumbus]

here are some photos of the brass from the first 6 rounds. aside from some scoring marks on the side i don't see anything unusual

[Lloyd Smale]

Try a dead blow hammer on the charging handle if that doesnt do it ive taken the buffer tube off and used a hook to pull a bolt back usually a couple good wacks with a dead blow does it. If it bends the charging handle no big deal unless its a high dollar one. i probably have a dozen spare cheap ones.

[Frank H]

Sounds like your case expanded too much or you have a stuck primer that blew out. Others have given good suggestions!

[Loudenboomer]

Ahh your in need of the AR repair kit. 18" 2"X2" and Lloyds Dead Blow Hammer!
Plunk testing all rounds greatly reduces the need of the AR 15 repair kit.

[Photog]

I've had the stuck case syndrome with 5.56, but never with 300aac.
I even sold an upper that I though was defective because the cases stuck all the time (pre-internet days), the buyer cleaned the chamber real good and it worked fine.
So, dont overlook that the chamber may be rough or dirty. I used a 45 cal brush chucked in a cordless drill with a bit of rubbing compound to polish the chamber of an AR that liked to stick cases, and it was cured.
I got really good at the mortar technique before I figured out the issue, I can attest that it DOES work, but often feels like abuse.

[gnostic]

That's happened to me several times when shooting ammo I loaded for my Mini 14, it chambers anything.
I went to small base dies and the problem appears to have gone away. Normally, I use the forward assist and that really locks it up tight. The military mortars stuck AR's on a hard surface, I wouldn't for fear of damaging the lower. They make test gauges that in effect, plunk test ammo before loading, I was thinking of buying one. The ammo in question was .002 large....

[NuJudge]

In all the shooting I have done with an AR15, I've never had one lock up, where I could not pull the charging handle back. I have had rims pulled off cases by the extractor, in which case a cleaning rod easily tapped the case out of the chamber. I will be really interested what you think caused this.

[farmbif]

presto, is this one of the first times using the gun? is this your first gun?
if you have the mind to get to know your weapon better maybe learning to take it down might be a good thing to learn.
AR's are very easy to disassemble and reassemble just need a few special tools that can be found pretty cheap. A couple punches and a couple different hammers and an AR multi function tool for $25
there is lots of places on internet with detailed instruction on building an Ar from bits and pieces.
for the $$ you pay gunsmith you could get all the stuff needed to disassemble and reassemble that gun properly. a wood dowel from Home Depot to knock out old shell. or if bullet stuck in barrel a long brass rod would be needed,
some valve grinding compound on a brass or mop style gun cleaning bit on a cordless drill to polish the chamber a bit and your probably good to go.

as others have said h110/296 should never be down loaded, usually there is a very small window of just a couple grains that are to be used in specific loads with that powder.

I'm certainly no AR expert but built 2 of them from scratch and it was surprisingly very easy once I got that AR multi tool, the right punches to install and remove roll pins. the most difficult parts for me was the assembly of trigger, it was just a matter of getting springs set right and shimming barrel nut that holds barrel guard to get it in correct position so rails line up.

[jim147]

What about a thick neck? I had to mortar one of mine. I had put a lot of rounds down it that day so think it might have been getting a little dirty.

I run them wet if I'm going to put a lot of mags through them.