Bolt Assembly not going forward completely

[Dualspringfields]

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

[Tweak]

how far forward is the bolt carrier when this happens?

[SMETNA]

Sounds like either FOD in the upper, or incorrect assembly of the BCG.

Are you sure the firing pin and FP retaining pin is installed correctly?

Are you sure the gas key is straight and tight?

[Iraqgunz]

Whenever your bolt freezes up like that there has to be something obstructed. You may not see it, or it may fall out while you are clearing it. It must have been a primer, or something that wedged in there.

Make sure that your gas key is tight and properly aligned. It sounds to me almost like you are experiencing a short-stroking issue as well.

I also wonder if there isn't a possibility that your chamber is too tight.


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

[Dualspringfields]

When this upper belonged to me I never ever ever had any problems with it at all. Never shot wolf in it though and am anal as hell about cleaning. This sucker locks up,meaning that I can't make it go any further forward at all. And the only way that I can make it come back/remove bolt assembly is to pry it with a screwdriver or something like that. It has only happened twice which in my opinion is too much.Once I get the bolt assembly out and put back in it works correctly. It just has me scratching my head here. I could see it not going forward comopletely if there is something in it's way. But why do I have to pry it out? It lacks about maybe a 1/4" from being totally forward.
Thanks for the ideas guys. I appreciate the help.

[Generalpie]

You have to pry it out because something is jamming it up. A "regular" function problem won't jam it up like that.

I assume you would have noticed something special like a double so the other options are snarf in the receiver like IG mentioned. A popped primer, crack rock, etc. or something burred or broken in the bolt.

I would take apart the BCG to all the little pieces except the ejector plunger and inspect everything for something odd. Inspect the empties for popped primers and make sure the ammo is good. i.e not bulged or otherwise over size.

Maybe I missed it but when it locks up is there a live round in the chamber?

[Dualspringfields]

Yes live round is chambered. I'm going to take bolt apart when I get home hopefully. I did notce yesterday that the extractor pin was loose. I'm going to compare it to my bolts. Wondering if it's time to change spring.
If it was something like a primer I would think it would do it every time.

[Dualspringfields]

Took bolt loose just now and replaced the extractor spring and reintalled. The extractor pin was loose and very easy to remove. Now have to use a punch. Thinking maybe I have found the problem or at least a problem. Hopefully I can get the guy to bring upper over today.


Ok heres what I have found.
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.