Help with failure to eject

[LAL6]

I shot my 6.8 today for the first time and was having a couple issues. About 25% of the time I was having a failure to eject, and then having a new round jammed in behind the fired case. The fired cases were still seated fully in the chamber each time, but fell out easily. A couple times I was able to cycle through a whole mag with no issues, but I was usually getting 2 or 3 FTE's. Here's what I'm using

Bison Barrel
LMT enhanced 6.8 bolt
Young NM carrier
MEGA upper
AR stoner 10rd. mags
Remington UMC 115gr. FMJ
Spikes ST-T2 buffer
spikes spring

The extractor seems to be in good shape, with no brass or anything jammed behind it. The gun seemed to be cycling fine, ejecting brass(the ones it did eject) at about 4:30 5 feet away. I did put a carbine buffer in it just for the hell of it, still cycled fine. I'm thinking maybe the extractor needs to be broken in a bit, or needs a little more lube. I don't think I ever lubed the bolt face before shooting. Any more ideas on what's wrong would be a big help. Thanks.

[dieselpower]

its the extractor...has to be. Its jumping the rim and not pulling the round. Sounds like the dwell is off and the case is compressed against the chamber walls when the BCG is attempting to extract...since it cant the extractor jumps the rim halfway back. Sometimes it will expend so much energy that it will short stroke and not attempt to feed another round... it will just slam closed chambering the old case at the same time. Sometimes it will have the required energy to pick up the next round and attempt to feed it... that will normally happen when the case is half out since it didn't clear the port before the Bolt face separated from the case.

I would slow the BCG down more and see if that fixes the issue. Make sure the chamber isnt dirty causing the case to stick.

[FatalKitty]

possible weak extractor spring?

[dieselpower]

possible weak extractor spring?

yeah I'd try that as well. Could be that simple.

[LAL6]

its the extractor...has to be. Its jumping the rim and not pulling the round. Sounds like the dwell is off and the case is compressed against the chamber walls when the BCG is attempting to extract...since it cant the extractor jumps the rim halfway back. Sometimes it will expend so much energy that it will short stroke and not attempt to feed another round... it will just slam closed chambering the old case at the same time. Sometimes it will have the required energy to pick up the next round and attempt to feed it... that will normally happen when the case is half out since it didn't clear the port before the Bolt face separated from the case.

I would slow the BCG down more and see if that fixes the issue. Make sure the chamber isnt dirty causing the case to stick.

Thanks for the good explanation... I do remember atleast once the bolt closed on the old case, but it would mostly try to feed another round.

I should probably pick up a heavier buffer and try that, it'll be a cheap fix. If not, I have an extra part. I took apart my bolt and the "enhanced" extractor doesn't have a real good edge on it, compared to the normal extractors that I have. That could just be LMT's design of the enhanced extractor. The springs were in good shape.

[torquefliteterror]

you should try an adjustable gas block. It would be a good experiment. I just recently bought a .308 upper from the scums at blackthorne(was curious if all the bad stuff about them was true- turned out mostly true) and they had hogged the gas port out to almost 1/4". the upper was doing the exact same thing. I bought a KIES adjustable gas block and was able to solve the problem after a couple of turns of the screw. now it cycles the way it was suppossed to.

[torquefliteterror]

the KIES are small and made of all steel construction. they are cheap too , like $34 shipped. the jp one looks great but costs a small fortune.

http://www.joeboboutfitters.com/Kies_Adjustable_Gas_Block_Low_Profile_p/kies-adj%20gas%20blockgen2.htm

http://www.brownells.com/.aspx/sid=52861/pid=7592/Product/AR-15-M16-ADJUSTABLE-GAS-BLOCK?utm_medium=shoppingengine&utm_source=googlebase&mc_id=10000&gdftrk=gdfV21820_a_7c187_a_7c3466_a_7c452000065_d_452015110_d_10868

[supersonic]

Sorry about the threadjack, but ^^^ YOU ^^^ actually bought an upper from Blackthorninmyside "just to see if the bad stuff was true????"

(BTW, you can go back and do such things as EDIT THREAD, DELETE THREAD, etc. instead of multiple double, triple and quadruple posts all stacked up on top of each other. Just sayin')

you should try an adjustable gas block. It would be a good experiment. I just recently bought a .308 upper from the scums at blackthorne(was curious if all the bad stuff about them was true- turned out mostly true) and they had hogged the gas port out to almost 1/4". the upper was doing the exact same thing. I bought a KIES adjustable gas block and was able to solve the problem after a couple of turns of the screw. now it cycles the way it was suppossed to.

[torquefliteterror]

Sorry about the threadjack, but ^^^ YOU ^^^ actually bought an upper from Blackthorninmyside "just to see if the bad stuff was true????"

(BTW, you can go back and do such things as EDIT THREAD, DELETE THREAD, etc. instead of multiple double, triple and quadruple posts all stacked up on top of each other. Just sayin')

$550 for a 308 is crazy cheap. I had to find out how that could be. the barrels look good but it's obvious that they cut corners on the rest of the parts.

all in all, if you really wanted a low cost .308 and you were good at trouble shooting, I think the carbine kits is decent enough. I'll stick to dpms and armalite stuff for now on though. I guess it's no different then people paying alot for glock perfection, then needing to send it over to you for trigger jobs and upgrades. not so perfect after all.