AR jamming/bolt not locking back problem

[rhs]

Been having problems with my AR not cycling reliably for the past while. I've pretty much ruled out mags, since it does this with a variety of LAR and PMags.

It appears that the bolt does not go back far enough to give the next round time to come up before it gets pushed forward. The result is that the bolt catches the round about halfway down the case and jams it up into the barrel extension. Usually this results in a severely dented case and sometimes the bullet gets pushed back into the case. This doesn't always happen with the first or last round in the mag; it occurs randomly. Quite often the bolt doesn't lock back on the last round, about 50 percent of the time.

Am running a 16" barrel with a mid-length gas system, Spike's buffer, and a Magpul UBR. Standard carbine buffer spring. I'm thinking that either the buffer is too heavy, I need to clip off a bit of the buffer spring, I need to shave off a bit off the plastic on the back of the buffer, or the bolt that attaches the UBR to the back of the buffer tube projects a bit into the back of the tube.

Any suggestions as to which of these options is the most likely, or any other suggestions. Need to get this sorted out before a match next weekend.

Thanks.

 

[P0WERWAGON]

make sure the gas key isn't loose. sound like a gas pressure issue

won't be the buffer length since it works at times. if the buffer was too long, then it wouldn't work at all.

 

[Satain]

Witch buffer do you have?
The 16" model should only have an "H" not an "H2".
Also if the gas tube is not correctly lined up with the gas whole on the barrel it will also show this problem.

 

[rhs]

Buffer is a Spikes Tactical T2, which I'm guessing is the same as an H2. Will try another buffer next range trip. My original buffer has no markings on it. I assume the H2 buffers are marked H2 somewhere ?

While it's possible the gas-hole in the barrel doesn't line up with the hole in the gasblock, I'm assuming that isn't the problem. It's a Noveske barrel and the gasblock attaches with both a setscrew and a pin through the barrel. I suppose they could have drilled the hole off-centre but I doubt it.

Bolt carrier is a Stag and it's staked, but will check if it is loose.

 

[RobSmith]

When's the last time you cleaned it ?

 

[alexD92]

Not running for the past while as in it used to work and now its giving you grief or it never ran reliably? Might have a problem with your ammunition.

 

[rhs]

Last cleaned about 100 rds ago. Bolt is well-lubed. Checked to make sure the gas rings were spaced out. Am going to go weigh the T2 buffer and compare it to the other one that I have.

If I can determine any pattern, it's that it runs best with my 77g SMK handloads, which have a full case (24g) of Varget. I'm looking for a cheaper alternative for close range stuff, so have been trying some factory 55g before I start loading 55g.

 

[acrashb]

I assume the H2 buffers are marked H2 somewhere ?

Usually "H2" would be stamped on the front of the buffer (the part that contacts the bolt carrier). Spikes uses different markings and a non-standard weight anyway.

H2 should be 4.7oz, H would be 3.8 and is the default on a carbine.

Spacing of gas rings is irrelevant.

I think that Noveske has smaller gas ports on the assumption that you'd be running 5.56 (higher pressures than .223), which combined with a Spikes T2 (which is supposed to be 4.3oz, in between the H and H2) could be the issue.

Anyway, if the gas key is tight try a lighter buffer next. Don't start cutting coils off of the spring, you can't glue them back on.

 

[ViktorF]

have you used a .22 conversion kit in it? Without cleaning the tube out or running hot .223 thru it Ive seen the gas tube plug up from crappy .22's.

just a thought.

 

[angryeyebrows]

I would say try other buffers and thoroughly inspect that the UBR is correctly installed and nothing is protruding into the receiver extension. Definitely do not start cutting or shaving things until you are 100% sure.

 

[coldfire]

clean gas tube, check for ring alignment on bolt, lube and lube some more. get a buddy to watch you shot it, see it any gas escapse up around the gas block check to make sure you gas tube ain't pinched some how. don't cut springs until you have ruled everything out. then before anything else take it to the range when and if a buddy is running his and ask help. just my 2 cents

 

[33hoffman]

i'm thinking gas key or ammo issue. if nothing else, give the gas tube a good cleaning, lots of people neglect it but occasionally it can get plugged.

.02

Matt

 

[jmiddy]

Alot of people neglect their extractor springs, if its not ejecting the cartridge properly it causes jams in feeding the next cartridge.
I too reload and my reloads never have a problem, i changed my ejector spring last month because it wasn`t extracting factory 55g properly works like a charm now!
My advice is to keep a few of these on hand.

 

[Dawg]

Having put a lot of rounds through a C7 & C8. Try a field expedient method of spraying some carb cleaner down your gas tube.

 

[7.65 Para]

Non-working AR is the failure of the operator - failure to maintain the weapons properly! ( or buying AR that is not built to the proper specification)

 

[kingair]

Did u clean out all the crap inside the extractor of your bolt? Most people do not clean this on their bolts.

 

[azn_hitman]

i had the same problem. bolt not locking back sometimes and sometimes not picking up rounds. i cut my buffer spring little by little until it worked without a hitch.

 

[FPembleton]

Assuming your rifle is put together properly, a 16" midlength Noveske complete rifle comes with an H buffer.

 

[Rugerman]

Alot of people neglect their extractor springs, if its not ejecting the cartridge properly it causes jams in feeding the next cartridge.
I too reload and my reloads never have a problem, i changed my ejector spring last month because it wasn`t extracting factory 55g properly works like a charm now!
My advice is to keep a few of these on hand.

Good point. I had a similar problem. I replaced the extractor spring with a stronger one and a thicker "donut" that the spring sits on. End of problem.

 

[rhs]

Thanks for all the suggestions. I weighed my spare buffer and it is an 'H', so that's the first thing that's going back in. The rifle is not a complete Noveske, only has a Noveske barrel group. I don't have a spare extractor spring, but the gun is ejecting cases well, dumping them about 5 feet to the right and about 2 feet behind. The upper is a Stag that I bought new, complete with a Stag bolt/carrier. I replaced the Stag bolt with the one that came with the Noveske barrel group, so I'm going to put the original Stag bolt back in as well. That bolt is pretty much new, so should have good springs in it.