Problem with LC 7.62 brass

[Coyote]

I've racked my head for so long on this that I have finally came here for help. I have a complete from Aero Precision
AR10 that I use for long range matches. I was using exclusively LC 7.62 brass with matching year. It worked great! I decided to buy a Wilson Combat Super Sniper barrel and adjustable gas block. If I run it suppressed then I can get about 10 rounds before it sticks the case and rips the rim off. Unsuppressed I can get about 5.

No amount of adjusting the gas block helps. I've noticed that the case is clean but the shoulder and neck is dirty. I tried turning the necks but I had the same results. I tried contacting WC about chamber specs because I was wondering if it was just a tight chamber but they wouldn't help me.

I had some Winchester brass and tried it and it would eject it with no problems. I know LC brass is thicker than commercial brass so I'm leaning towards a tight chamber. I have already switched to a heavy rifle buffer trying to slow the bolt down and it helped but the problem still persists.

I know where the brass came from and it was not shot in a MG. I'm also using the Lee dies and I'm wondering if maybe RCBS dies would bump the shoulder back a little bit more and if that would help. I'd hate to have to shelf all of this brass and switch to commercial brass.

This problem has become a money pit and local gunsmiths are throwing out ideas but no real solutions.

[Scorpion Rider]

I had problems with lee dies and proper sizing for rifle brass (too big for chambers). I now only use lee dies for pistol reloading (straight wall). I do use the lee crimp dies on everything since I like to crimp in a separate stage and they seem to work fine. Try better quality dies.

[Coyote]

Try better quality dies.

RCBS or Lyman? In your opinion.

[Scorpion Rider]

I like forester dies for 300 blackout and have used RCBS and Redding with success for other calibers. Maybe Wes will chime in with his recommendations, since his processed brass seems to work in everything I shoot.

One question before you start buying new dies. What press are you using?

[Coyote]

One question before you start buying new dies. What press are you using?

I have a Lee single stage, RCBS Rock chucker and a Hornady LNL AP.

[Scorpion Rider]

I have a couple of the Hornady lnl presses and use them for all my reloading, but have heard of people having certain problems with progressive presses when full length resizing. Have you done the 308 reloading on the same press? If so maybe try another press. If that’s out the window then it’s about the dies. I just checked what 308 dies I have been using and they are the Redding premium die set and a lee crimp die. Not cheap, but they give more precise bullet seating and have given me good sizing every time. I use a Lyman case gauge block set when checking my loaded ammo since they are cut to minimum sammi specs. If they fit they chamber for me.
Good luck

[Oddduck]

I've racked my head for so long on this that I have finally came here for help. I have a complete from Aero Precision
AR10 that I use for long range matches. I was using exclusively LC 7.62 brass with matching year. It worked great! I decided to buy a Wilson Combat Super Sniper barrel and adjustable gas block. If I run it suppressed then I can get about 10 rounds before it sticks the case and rips the rim off. Unsuppressed I can get about 5.

No amount of adjusting the gas block helps. I've noticed that the case is clean but the shoulder and neck is dirty. I tried turning the necks but I had the same results. I tried contacting WC about chamber specs because I was wondering if it was just a tight chamber but they wouldn't help me.

I had some Winchester brass and tried it and it would eject it with no problems. I know LC brass is thicker than commercial brass so I'm leaning towards a tight chamber. I have already switched to a heavy rifle buffer trying to slow the bolt down and it helped but the problem still persists.

I know where the brass came from and it was not shot in a MG. I'm also using the Lee dies and I'm wondering if maybe RCBS dies would bump the shoulder back a little bit more and if that would help. I'd hate to have to shelf all of this brass and switch to commercial brass.

This problem has become a money pit and local gunsmiths are throwing out ideas but no real solutions.

Try using a small base sizer die, I've never had any problems with Lee dies in any of my semi auto rifles

Sent from my SAMSUNG-SM-T337A using Tapatalk

[Harter]

I'll call this lemons and limes or maybe cuties and oranges ......

A similar situation with a 6.8 in an AR 15 . When I was working up my load I had reached the point where I was happy with the groups but not quite getting the function . It wasn't locking open , it would eject and pick up. The next step had it holding open on the follower , one more step up and .......nope back to eject and pick up but no hold open . The groups went South with the next step and failed to eject . This set up was already proven with factory ammo and was settling in nicely . Ejection showed slightly over gassed . It was a case of everything aligning just so and the pressure was just high enough to keep the case stuck to the chamber walls and full volume and just barely not enough to damage brass or defeat the friction . I changed the barrel from the Wilson 16" Carb gas to an ARP 20" rifle . The load is no longer over gassed , the upper load with ejection failure is the first step that opens up and I gained 200 fps . I readily admit that an installed barrel on a $400 just add a stripped lower kit might not shoot like a $250 just the barrel component and that 4" can make major velocity gains .

In the interim between what I had and what I got I switched from 4198 to H322 for a 130 gr bullet I sacrificed a half inch on paper , 100 fps MV but the rifle ran 100% for the next 500 rounds , over gassed .

In order of what I would try , not necessarily what is the best way or what is available .

Clean the gas tube , port , block , and BCG and lube it . A piece of drill burr , carbon etc , could be causing a "retard pressure building" situation where the gas volume/flow is mimicking over gassed .

Long or brass with a "neck doughnut" inside . Just because it's spec doesn't mean doesn't mean it will fit . I had 2 M92' carbines in 45 Colts with a spec case length of 1.285 the chambers were 1.305 and just short enough to keep a a 454 from chambering . They also refused to feed RP in any flavor .

Powder conflict . I had a box of Win white box 22-250 45 gr on a hot day shooting a Mk X varminter 98' . At 1 round about every 45-90 seconds the 7&8th rounds showed gas leaking and the 11th dropped the primer in the action . A week later I reproduced the experience with 3031 about 2 gr under max with 55 gr SP .

I would fire a steel case and thread the primer pocket and lap/polish the chamber with attention to the top/front half . Use a 1200 or more lapping compound , Flitz , or a course rubbing compound , if you're sure it's a chamber issue .

If you've stuck it out this far I can offer further weirdness .
I had a Ruger BlackHawk 45 Colts that with identical 800 fps 255 gr plinking loads would drop Starline , FC , and Winchester brass out freely or with a touch to move it but every piece of RP feels like the chambers are full of sand .
I had a Remington 760 06' that shot it's best with Winchester brass .
A Winchester M70 06' that really liked RP but not WW .
An 03A3 11/43 Rem that threw LC 43 and Den 54 all over , Hornady in FC was best but still sucked .
Last but not least a Savage 110 that lived for weigh lotted LC brass .