Excess pressure or rough bolt?

[Jeepfe]

Ok, I forgot, just pulled the buffer out. It has a rifle length buffer and spring. I used a Magpul moe rifle stock so I have a rifle length buffer tube, buffer, and spring.

And there is likely half your problem.

Carbine gas, carbine buffer 3 OZ.

Rifle buffer will be heavier. 5 OZ

This is probably why you have over pressure signs, and at the same time short stroking/not locking back.

Confirm your buffer weight, then if you need to change to a carbine buffer you will need a spacer. Rifle buffer should be about 6", carbine a little over 3.

The rifle buffer I have is 5.1 oz. thanks for the advise. I'm going to rob the carbine buffer and spring from my other gun and give it a try. Brownells sells a spacer for $8.99 but I may try to make one. If anyone has the exact dimensions for a spacer to put a carbine length buffer and spring in a rifle buffer tube I would appreciate the info. I have access to a everything I need to machine/cut one to size. The one from brownells says 2 1/8"

[RLunyATL]

Sorry to dredge up a 2 month old thread, but I'm confused by some of these posts. One guy is telling OP that an H2 buffer (heavier than standard carbine buffer) will fix his problems, while another is telling OP that a lighter (carbine as opposed to rifle) buffer will fix his problem. While I understand the lighter buffer fixing the issue of the bolt not locking back, it doesn't make sense that it would help with an overpressure situation. Seems a heavier buffer would keep the bolt locked in battery slightly longer allowing pressures to drop before unlocking to extract the case. Someone help me understand these conflicting posts.

[dellet]

Sorry to dredge up a 2 month old thread, but I'm confused by some of these posts. One guy is telling OP that an H2 buffer (heavier than standard carbine buffer) will fix his problems, while another is telling OP that a lighter (carbine as opposed to rifle) buffer will fix his problem. While I understand the lighter buffer fixing the issue of the bolt not locking back, it doesn't make sense that it would help with an overpressure situation. Seems a heavier buffer would keep the bolt locked in battery slightly longer allowing pressures to drop before unlocking to extract the case. Someone help me understand these conflicting posts.

Probably referring to this:

Ok, I forgot, just pulled the buffer out. It has a rifle length buffer and spring. I used a Magpul moe rifle stock so I have a rifle length buffer tube, buffer, and spring.

And there is likely half your problem.

Carbine gas, carbine buffer 3 OZ.

Rifle buffer will be heavier. 5 OZ

This is probably why you have over pressure signs, and at the same time short stroking/not locking back.

Confirm your buffer weight, then if you need to change to a carbine buffer you will need a spacer. Rifle buffer should be about 6", carbine a little over 3.

The OP likely has two separate problems, maybe three.

From his description of the brass, he's over pressure. Ejector swipes.

It won't lock back on empty, could be under gassed, or over gassed. Since he is running a rifle buffer, it's the most likely cause. A carbine system was designed to run with a carbine buffer.

If he corrects the known problem with the rifle, then he can start working on the others.

If he is pounding the brass into the bolt face hard enough to forge it into the ejector hole and have the extractor bend the rim, there is an chamber or ammo problem. Nothing but pressure will cause that.

If the extractor is pulling the rim the other way, the bolt is unlocking too soon and you can correct that by using a heavier buffer or cutting off the gas. This is a timing problem and can happen even if pressure is not a problem.

Basically fix one problem at a time or you will chase your tail forever.