BCG hitting back of receiver and buffer tube

[mtrmn]

So to add to my original post and explain my caveat that it may be irrelevant here, the cupped quarters come from my blowback 9mm PCC, and it has an unconventional buffer that I'll include a pic of. It takes about 3-4k to kill a stack of quarters( @Gustav7 ), but it didn't do any damage to the buffer tube in about 10k rounds with no quarters.
I was pretty alarmed the first time I found said quarters, but multiple threads on forums dedicated to USPSA PCC tuning (where short stroking with quarters standard practice) indicate it's a very well known and common phenomenon with all sorts of different buffers, including regular rubber bumpered ones.
So again, maybe not pertinent to locked breech rifles, just pointing out that quarters aren't necessarily an invincible short stroke solution.
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I've never had any experience with a PCC. No way to tame it down?

 

[TonyTheTiger]

I've never had any experience with a PCC. No way to tame it down?

Lots of ways, and those quarters are after the taming has been done. Obviously gas adjustment is out of the question for most platforms, so you're left with ammo/bullet weight tuning, buffers of all different weights, spring rates and then a huge selection of weird buffer designs, like the 3 stage internally sprung unit I have, magnetically delayed, hydraulic, air cushion, even a roller delayed buffer where the rollers lock into a special buffer tube. Then you have stuff like CMMG's radial delayed blowback and other proprietary systems as well as gas guns (MPX) and roller delayed (MP5, JP5). All in a mostly failed attempt to make a 9mm rifle recoil as pleasantly as a DI 5.56. The roller and gas guns are soft but complicated, the rest will always be pretty rowdy.

 

[mtrmn]

Thank you for taking the time to explain this to an old knuckledragging mechanic. I'd never looked into PCC's and just assumed the AR style just worked like an AR-with a locking bolt and a gas system.

 

[TonyTheTiger]

Thank you for taking the time to explain this to an old knuckledragging mechanic. I'd never looked into PCC's and just assumed the AR style just worked like an AR-with a locking bolt and a gas system.

I have heard of a few companies trying to develop direct impingement rotating bolt PCC's that work just like regular AR's. They even have cute little gas tubes, like 1" long. I have not heard of any of those companies successfully getting their designs to market though...

 

[mettee]

I'd recommend a rifle buffer spring, 3.25" super heavy buffer(maybe slash xh), and a 7.625" deep receiver extension, you are shooting suppressed and your brass is ultra dirty it should not be that bad, you are still unlocking too early.

The BCG seems like that rear section is bad, but the rear edge of the bearing surface should not travel that far back....I'll look when I get home. Eta, that sharp corner is only an issue because your bcg over travels.

You said the buffer doesn't bottom out, so yeah it needs new parts.