Feed issue

[BytorJr]

I'm having an issue where the previous round is apparently stuck to the bolt face. Sounds like an extractor issue except this problem arose at about round 5 (brand new upper) and pops up pretty routinely. Result is the fresh cartridge doesn't make it up in time and the spent cartridge is trying to go back in the chamber but doesn't quite make it before the round from magazine pops up - resulting in a 2-into-1 issue.

Running Geissele carbine length spring/h2 buffer. My guess is that either the spring is way too powerful (UBR - 1 stock) or the buffer isn't heavy enough and it's not slowing it down.

Thoughts? Never had an issue like this before, so it's a learning opportunity.

Thanks.

 

[XLR308]

Check the ejector plunger for binding or being gummed up.

 

[Jackalope]

Check the ejector plunger for binding or being gummed up.

Agreed. Seems like the place to start.

What are the other details of the rifle? Barrel length, gas system length etc.?

 

[Bullspotter]

AR10? 15? what caliber, If you load 1 round in a mag and shoot it, dose the bolt lock back? Adjustable gas block?

 

[BytorJr]

@Bullspotter:
1) 15
2) Don't know if I tried that or not. Forgotten. Will try next time to shoot a few rounds that way.
3) non-adjustable (LaRue Stealth Upper) - aka...ship's anchor

I'll check the plunger. Shouldn't be gummed up because it hadn't been shot; but was cleaned. Maybe it's still gummed or has crap in it.

Thanks!

 

[Lange Carabine]

Had this issue with an upper once. May run fine for 3 or 4 rounds then do the same thing you're experiencing. Bolt locked back fine loading one round. I tried rifle and carbine buffers and 3 different bcg's and it still short stroked. Drove me nuts for a couple day before the light bulb came on
Problem was caused by the gas block being jammed up tight against the journal shoulder partially blocking the gas port in the barrel. Loosened the screws and slid the gas block forward .020" and problem solved.

 

[BytorJr]

Agreed. Seems like the place to start.

What are the other details of the rifle? Barrel length, gas system length etc.?

I think you were onto something. I haven't dissembled the entire bolt, but holy shit. My other bolt carrier's bolt plunger is fairly easy to push in with a flat screw-head. But the one that's failing is almost impossible to push in. It pushes, but the amount of force is quite nuts. It got better the more I shot; but I may switch bolt carriers and see if the other one works. Not my preferred method, but I don't have any extractor springs handy (I probably have them...but where is next weekend's task...the "ready" weekend).

 

[BytorJr]

Had this issue with an upper once. May run fine for 3 or 4 rounds then do the same thing you're experiencing. Bolt locked back fine loading one round. I tried rifle and carbine buffers and 3 different bcg's and it still short stroked. Drove me nuts for a couple day before the light bulb came on
Problem was caused by the gas block being jammed up tight against the journal shoulder partially blocking the gas port in the barrel. Loosened the screws and slid the gas block forward .020" and problem solved.

This will be my fallback plan. But that bolt's plunger is very stiff. Almost jammed. Then I noticed the stake marks on the bolt were rough as hell so I filed them down to avoid cut fingers. Unbelievable. Not sure why I used to believe that company built great stuff. Good stuff yes, great...meh. Nice triggers though for 90 bucks. First thing I need to address is get rid of the quad rail and go to M-LOCK and lose 18 OZ. I don't know why those LaRue's are so heavy.

 

[BytorJr]

AR10? 15? what caliber, If you load 1 round in a mag and shoot it, dose the bolt lock back? Adjustable gas block?

well, that plunger on the bolt face was impossible to push down. So, I've got a rebuild kit for that but debating on just putting a new bolt in and trying that. Different issue than my other problem. Never had this much trouble before.