Bolt assembly not completely going forward

[Dualspringfields]

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Got a problem. 1st off not my weapon. Use to be my upper. Stag 16" carbine length on a RR lower. This has happened twice. After shoting a around bolt ejects spent casing but bolt doesn't totally go all the way forward. Friend has been with me each time this has happened so I have been the one trying to unjam it. Bolt assembly will not go completely forward at all. No matter how hard I push. Wont come back either. I pulled on the changing handle so hard I thought I was going to break it. I have to totally take the upper off the lower and either use a flat head screw driver or a thick knife to pry the bolt assembly back. Once I get it out of the upper I check it out and can't find anything wrong. After reinstalling bolt assembly and after putting assembly back into upper it all works correctly. Before yesterday friend shot nothing but Wolf and the like in the rifle. After the first time it happen (which was the last time he shot) he bought Winchester 55gr fmj. This is what he shot yesterday and had the same problem. It happened yesterday after about 30 rounds. The time before I have no idea 200 rounds maybe. I doubt that it has been cleaned correctly since it has left my house. I replaced the bolt with one of my extra BCM bolts. Need my bolt back. Anyone have any ideas?????????????????????

Thanks Casey

[markm]

How close to going into battery does the bolt get? Is this happening with a live round in the chamber?

[Dualspringfields]

It lacks about a 1/4" or less from being in battery . Yes live round.

[twisted75gr]

Possible the bolt is siezing in the carrier right at lockup how well lubed is the BCG, bolt, gun? Have you checked the bolt itself, gas rings, cam pin...how well, or easy does the bolt move in the carrier? possible debri caught up in the bolt?

[Dualspringfields]

Thanks guys. Bolt looks good. I put it in one of my assemblies and it ran fine.

[markm]

Tight/steel case filthed chamber perhaps.

[Dualspringfields]

Steel cased ammo the first time, brass the second. I'm starting to lean towards jacked up bolt. It has happened only twic, which is too much. Thinking the bolt is getting hung up in the carrier somehow. I'll have to get the BCG and his bolt and finger it some more.

Thanks for the help and suggestions. Casey

[Striker071]

Casey. remove the bolt from the bolt carrier group. You may have debris that is blocking or impeding the cam pin from moving its full range. compare it to your BCG that works properly.

Good Luck

[Dualspringfields]

Thanks. Gonna go by the guy's house when I go home and get it.

[markm]

Yeah... could be a blown primer somewhere in the bolt group... or even the lower half. Those things will move in and out of position to where they cause periodic malfs.

[zero7one]

I know you have a lot of suggestions so far, but to throw mine into the hat....I would thoroughly clean the rifle and properly lube it. While you have the bolt apart, check all of the parts to ensure everything is still in working order. It doesn't sound like it is a gas issue at this point since it will eject the spent casing, but not fully seat the bolt on the return. Another thing to check out is the magazine. If you are having a feeding problem, could be the magazine. Does the bolt not seat properly when the mag is inserted vs. when out? I would say that the #1 culprit is a dirty and underlubed gun.

[Dualspringfields]

Just changed the extractor spring. Waiting for the upper to make it to my house. Insert was wore out didn't have much tension there. Pin was ease to get out. Barely pushed on it. Hope my riend brings it over today. I'll be looking at all your suggections.
Anyway thanks again everyone. I doubt it's been cleaned.

[Dualspringfields]

Saturday when this happend I unstuck it and removed BCG from upper. Didn't see anything wrong. Bolt moved back and forth just like it should. Took bolt out of BC and inspected it. Didn't see anything wrong there either. Dirty but I have seen waaaay worse.Reinstalled bolt and checked operation. Worked correctly. Took one of my extra bolts out of my bag and installed it into his BC. Installed in upper and burned a 30 round mag. No problems. He shot it several more times with no more problems.
I can see how if there was something in front of the bolt that would't allow it to to go into battery completely. But why Im scratching my head is why does just totally lock up? I dont care how hard I pulled on the charging handle the BCG wouldn't move at all. The only way was take upper off lower and use my Leatherman to pry it loose. Anyway one way or another I'll figure it out and I'll post what I find.

Thanks fellas

[csmith]

Check the area where the cam pin rides in the receiver, maybe the cam pin is catching on something?

[Dualspringfields]

Thank you. That's exactly what I thought too.

[Dualspringfields]

Found problem/problems. Extractor spring wore out resulting in there not being enought tension on the extractor pin. Pin was working out. Gas rings catching on the 2 holes on the side of the carrier. Do not know what these holes are called. But it's the 2 holes you see when you open the dust cover. The bolt didn't do this in my BCM carrier and my bolt wouldbn't do it in his carrier. I put his bolt back in his carrier and started moving it back and forth in the carrier. It finally hung up. Replaced rings. Couldn't get it to do it again. Informed friend that he needs to clean the crap out of the chamber. Filthy! Gave him a chamber brush. A clean weapon is a happy reliable weapon.

Thanks for the help.

[GroundtheGear]

Sounds like from what I understand in all the above is we have 1ST, the failure to lock during the "cycle of operation". All good probable causes mentioned above! I'm leaning towards a blown primer chewed up somewhere causing the stoppage. Another culprit that I didnt see/or missed mentioned is a weak or damaged action spring. Restricted buffer assembly movement ( proper buffer? action spring rifle or carbine?) Strange things happen when you start mixing upper & lowers w/ different manufacturers ( mil-spec/ comm.?) 2nd, now a seized bolt. A possible cause for the itch on your head and use of your leatherman tool might be the bolt will not rotate due to a burred or damaged barrel extension locking it up. Good luck! let us know or just buy a Colt! hehe.

[GroundtheGear]

Good deal! I misunderstood. I thought same prob. w/2 sep. bolts?

[Dualspringfields]

LOL. Not my upper anymore. I gave this upper my friend a few months ago. No blown primers. I inspected the chamber and related areas the 2 times this has happened and neither time was there anything like that. I'm with everyone else Definetly sounds like there was some kind of debis obstructing it. Never saw it if it was. 1st time was steel cased 2nd time was brass cased. 2 months apart. Found extractor spring wore out and gas rings needing replaced. Replaced them. Told him if it happens again to take it to our local "AR15" shop. As far as I know it could be his chamber. He still hadn't cleaned. I looked at it last night when he brought it over here and it is a nice dark grey. Since he has had the upper he has never cleaned the chamber. Excuse; Can't find a chamber brush at Acadamy.

[GroundtheGear]

LOL. With that excuse he really meant to say "No one will clean it for me!" And BTW... I replied and didnt realize you solved prob until my post popped up under yours on 2nd page! lol i will never post again lol!

[Dualspringfields]

Your more than likely correct. And your suggestions were all good ones. Thanks for replying.