AR15: bolt getting stuck

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fchan

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Hey guys,

Just got a new ar and I'm wondering if someone might know why I'm having this issue.

There will be a round in the chamber, bolt seems to be locked up, when I pull the trigger I get a "click", but no primer strike.

When I clear the round, the bolt is stuck. I don't have to mortar the rifle to get the charging handle to pull back but it's almost that bad.

There is no pattern on which round this happens on. Full mag or not.

The ammo is norinco yellow box brass cased. I thought it was the ammo but this happens on some of my dummy rounds too and the rounds that didn't go cycles through someone else's ar without issue.

When I take a round that was preciously stuck, I can drop it into the chamber and it will fall out easily leading me to believe the ammo is not out of spec.


Any AR gurus have an idea what I can do? (I'll be calling the manufacturer on Monday)
 
Cavs42 said:
Try a different mag?
Click to expand...

I had a few lar mags and the factory mag. It was happening with all of them, didn't seem to matter if the mag was full or not either. Sometime it would happen on the last round. The mag the rifle came with is stamped metal and very similar to the lar mag. Should I try something like a pmag?
 
First thing to do I go buy some decent ammo. Anything made in China is questionable at best and if it happens on other ammo then you may need to have a smith check your chamber dimensions or how your bolt lugs are engaging the barrel extension.

New AR? Did you clean it well before you used it? Could just be a bunch of grease and crap in the chamber.

Good luck

If you can't figure it out PM me and we can try to line up a day and I'll stop by and have a look at it.
 
cr5 said:
First thing to do I go buy some decent ammo. Anything made in China is questionable at best and if it happens on other ammo then you may need to have a smith check your chamber dimensions or how your bolt lugs are engaging the barrel extension.
New AR? Did you clean it well before you used it? Could just be a bunch of grease and crap in the chamber.

Good luck
Click to expand...

How is that though?

He said it happens with dummy/drill rounds as well.

Get it looked at first man, before you throw more ammo in it and it goes boom this time but not the way it's supposed to.

You or your rifle (or both) could get hurt.
 
Hmm, my spidey sense is pointing at your bolt. Have you detail stripped and cleaned your bolt and firing pin and such? I suspect it could be debris in/on your bolt that is sloshing around and causing intermittent problems unlocking.

If you remove your bolt carrier group, can you push and pull the bolt easily? It shouldn't take more than a finger to push the bolt in, and you'll be able to see it rotate as it does so.

Just an idea.

Edit: disregard the comment you saw here, if you saw it, scheduling problem.
 
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Had a similar type problem although sometimes everything would get jammed up only partly into battery and sometimes just like you describe.

Warranty fixed the feed ramps. I dont have it back yet but they say it now functions fine.
 
Travis Bickle said:
How is that though?

He said it happens with dummy/drill rounds as well.

Get it looked at first man, before you throw more ammo in it and it goes boom this time but not the way it's supposed to.

You or your rifle (or both) could get hurt.
Click to expand...

That's why I suggested cleaning it properly if he hasn't already. Could just be grease or crud in the chamber, especially if it's a Norc.
If the bolt closes and locks up how is it going to go boom? The hammer won't hit the firing pin if the carrier isn't far enough forward.
We don't know what he is using for dummy rounds. Maybe those are crap as well.

Not enough detail in the description to really say what is wrong, which is why I volunteered to meet him and have a look at it, I live just west of Edmonton.
 
This is easy to tell.

If it closes on an empty chamber probably OK. Headspace gauge would help.

Try different ammo. If it chambers, it was the other ammo.

This could be caused by very tight headspace, but is more likely ammo, since ARs generally have generous headspace to begin with.

Damage, fouling or pitting in the chamber could cause this - look inside with a light.

Re-loaded ammo will do this if not re-sized or not re-sized enough. Out of spec factory ammo as well.

Buy a box of high quality ammo and try it out then.
 
If I had to guess I would say that there is a blown primer that has gotten behind the locking lugs on the receiver. Norc ammo is know for this. I had the same problem with my AR. It seems there was on bad batch of Norc ammo that I had that would spit out the primers.

I hope this helps.
 
Thanks for the suggestions guys.

The ar is a pof. They are replacing the bolt for a different issue (flaking finish).
The rifle was stripped and cleaned before taking it out but I did not detail strip the bolt.
I didn't see any primers stuck in the locking lugs but I will take another look as well.

I'm 90% sure it's not an ammo issue, as the dummy rounds I made were resized before I put them together and the dummy round brass was Winchester stuff, not norc.

I'll speak with the mfg on Monday, hopefully they know what's going on and it's an easy fix as I really do like the rifle.
 
does it ever happen after chambering a round and NOT pulling the trigger?

It's possible that were looking in the wrong place and that it could be debris or something around the hammer, preventing it from resetting.
I.e., if the hammer can't be moved then it could be holding the bolt in place.
I've never actually heard of that happening unless installed improperly, just a thought.

I would try
1) take your BCG apart and inspect it, clean it, put it back together
2) ensure that the bolt & firing pin moves freely in the BCG while out of the rifle
3) with the upper and lower separated, insert the assembled BCG into the rifle, it should both lock-up and unlock easily using just your hand to move it, try just pushing it all the way forward and then pulling it back repetitively to make sure it moves freely. very little force is required.
4) take the lower and pull the trigger (releasing the hammer, you should hold the hammer so it doesn't just fly forward). Ease the hammer forward, then push it back to reset it. Do this many times to make sure that the hammer is moving and resetting freely. Where it sounds like your firing pin isn't even striking the primers, its possible (although unlikely) that your hammer isn't contacting the firing pin (hammer getting jammed) and then it cant reset (holds the BCG in place)
4) re-assemble the rifle, rack it repetitively a many times, everything should be smooth. since your problem is intermittent you may need to do this many times to be sure.
5) repetitively rack and dry-fire it every time you rack it (Do not chamber a round or dummy round!). Does it get stuck when nothing is in the chamber? since your problem is intermittent you may need to do this many times to be sure.
 
The only couple ways to really mess up the assembly of the bolt are (a) installing the cutter pin from the wrong side (b) installing the bolt with the extractor away from the ejection port. Well, maybe (c) installing the firing pin after installing the cutter pin which would be pretty obvious. Other than that, it's a no-brainer.

As Suputin pointed out, using home made dummy ammo doesn't prove anything as the ammo could easily be improperly sized. They may chamber in another rifle with more slop but doesn't guarantee it will in a tighter chamber. If it's sticking with factory ammo to a point where you may resort to mortaring it, something is off. I had that issue with some reloads where I didn't size the cases properly. It was just an issue of the ram not fully seating on the die by a couple thousand's of an inch.

As other pointed out. Do a couple quick checks.

- Remove BCG, examine for damaged lugs or improper assembly
- Replace BCG and see if it locks up fairly easily. It should just "click" into lockup with light pressure.
- Reassemble your upper/lower and work the charging handle. Does it move freely or does it feel like it is getting caught up/dragging?

If the above checks out, you can probably rule out the BCG being the issue.
 
Round doesn't fire and bolt is partially stuck. If the trigger mechanism works fine, i.e. the hammer falls forward when the trigger is pulled then is it possible that the bolt is not in battery? Burrs on the bolt locking lugs or on the barrel extension may prevent the bolt from seating fully and preventing ignition. The burrs could also cause hard bolt dis-engagement. I doubt that it's the mag or ammo. Anyway, just my $0.02 :p
 
It does sound like the bolt not going fully into battery and the hammer strike trying to help rotate it into battery, hence the hard lock up that requires effort to extract manually. Why this occurs, head space minimum with max OAL ammo, something interfering between bolt face and base of cartridge and creating too tight of head space to chamber and fully rotate into battery.
Like Travis said, sort this out so you don't get a discharge with the bolt not fully rotated into battery with the bolt lugs fully engaged. An AR kaboom.
 
RememberTheSomme said:
It does sound like the bolt not going fully into battery and the hammer strike trying to help rotate it into battery, hence the hard lock up that requires effort to extract manually. Why this occurs, head space minimum with max OAL ammo, something interfering between bolt face and base of cartridge and creating too tight of head space to chamber and fully rotate into battery.
Like Travis said, sort this out so you don't get a discharge with the bolt not fully rotated into battery with the bolt lugs fully engaged. An AR kaboom.
Click to expand...

The firing pin can not extend past the face of the bolt unless the bolt is rotated into battery.
 
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