So I had a Fulton Armory Carrier with a JP Enhanced bolt for several years and my LR308 build has not worked right ever.  Constant FTE FTF issues. JP sent a new extractor after it was realized I had the original style extractor.  I still have the same issues after installing the new extractor kit.  So I am ditching my BCG and going with a complete BCG.

I am looking up Spikes Tactical, Lantac and Aero Precision.  Any others I should add to the list?  I am not going with JP since they have gone silent when I reported I am still having issues.  It will be sitting in a MaTen upper/lower set with a Rainier Arms 20" Ultramatch rifle.  I have quite a bit of money put into the build, so I don't mind spending a little extra cash for a good BCG, but I am not paying over $350.  So JPs and LMT are out of the question.  The key is reliability and precision.

KAK

Lantac

Do you have an adjustable gas block on it?
I have an Armalite AR10 that always had feed problems. I put an adjustable gas block on it and it now runs like a clock.  I think a lot of feed problems can be caused by being overgassed.

the KAK one works good for me also

What it is about this thread?

Attached File


I was going to suggest the JP bolt, but it looks like you've tried it.
LR308's have known issues with extractor / barrel extension clearance.
Are you sure your issues are bolt related?

Im running a Toolcraft BCG with a SLR Sentry 7 gas block with 0 issues. Your issue sounds like you may have a compound issue. Can you elaborate on what is occurring during the failures to feed and failures to eject?  Are you running an adjustable gas block?

KAK double ejector is what I used in my 12.5 Aero build.

RDTCU,
I noticed the two first post after I replied. I guess it just worked out that way. After reading the OP I thought of my own experience and thought I could help. He has quality parts and they should work. It's my first post, but I've been building ar's for over a decade.

Thanks

I’ll 4th on the KAK. Have one in my 12.5 inch 308 and works fantastic. Zero issues.

It is the root of a lot of problems on the LR308s.
I added a RCA adjustable gas key to mine, it stopped yanking rims and leaves the brass a couple feet away instead of over against the wall.

Next one I get is going to be one from here...  ==>BCG

Mystic Black has the lowest coefficient of friction.  They are made by ToolCraft and coated by Cryptic.

Is it worth the $135 premium over nitride?
I supposed ease of cleaning is worth something...

I don't know yet.  When I do get one I'll write it up and post.  With the low coefficient of friction that should open and close pretty easy, especially between bolt and carrier.  Not going to help an over gassed situation.  I want to redo my 16" carbine with an adjustable gas block and light weight buffer, try to reduce reciprocating mass. Thought this might be the ticket.  Wish they made their low mass carrier for a large frame.

Most of the bolt/carrier friction comes from the gas rings.  The bolt bore on the carrier is chrome lined.  I'm not seeing whether or not they coat over the chrome lining, but I'm guessing that they do not.

Ill vote for Lantac. But, I havent shot mine yet. Hoping to fathers day before SLAYER!!!!

However, racking the bolt by hand, it is stiff when unlocking from chamber. BCG in hand, the bolt is rather tight in the carrier. Tighter than I like, I think its a one piece gas ring, but I have ripped it apart yet. Shoved it in the upper, chambered a few rounds, it ejects by hand just fine. We will see what happens under pressure.

Also, the Armalite bcg is a superior design as well. The gas vents helps tremendously with gassing issues, you cant simply scale the AR15 up and be done with it. Not how it works. Which is why the DPMS pattern has many gassing issues.

LMT, KAC, LaRue, Armalite, I think Wilson, but every picture of their large frame guns has the port door closed, JP has their own ways of handling it.

Without adequate venting at the carrier, you will have over gas symptoms even when your gas port is within spec, or even just a bit small. Without proper pressure relief, what do you get? Over pressure in the carrier, which is exact same symptoms of being over gassed. It is the same thign technically.

But I would suggest the Armalite, you could even get away with using a different bolt to match it up, but check headspace. Possible youll need different type gas rings if things are too tight or too loose.

Buy from people who have been doing shit the longest. Doesnt necessarily guarantee the best, but is a higher probability of it being done right the first time.

I should have noted that i do run an adjustable gasblock. Actually on my second because i thought my first adjustable gasblock was the issue.

I ran the gas block to hold open on the last round and ran it to the point the gun would not fully cycle.

Typical issues include failure to eject. Either stove pipes or the spent brass lodged in upper. Couple instances of brass not extracting. But brass will extract when manually ejected by hand.

Either way i ditched the bcg already and looking for a new part to try something else.

Running a Mega Arms Maten upper/lower (Non-monolithic). I was running a Magpul UBR Gen1 with Slash CAR10 buffer and JP polished AR10 carbine spring, but just switched out the recoil system to a standard Carbine extension setup last week and waiting on a bcg now. I've also tried standard DPMS CAR10 buffer and DPMS AR10 springs.

Running a SLR Rifleworx DA7 adjustable gas block.  I previously ran a Syrac Ordnance adjustable gasblock.

Rainier Arms 20" rifle length bbl w/ DPMS style extension in .308.

No damage to the buffer tube or lower.

Regardless, I am still in need of a BCG now.

Lantac E-BCG 308 are on sale at Primary Arms for $260, so I am considering going that route.

When reading the highlighted my first though is chamber pressure is too high while its trying to extract the case.