gouged brass on M1 Sales upper

[kdiver58]

That is some pronounced gouging .. I've never had that and I'm using the Pmags and 220 SMK's. Good luck ..

[Flewis]

Originally Posted by kdiver58

That is some pronounced gouging .. I've never had that and I'm using the Pmags and 220 SMK's. Good luck ..

Kdiver, what COAL are you using?

[pug]

By the distance apart I would think only the feed ramps could be doing that kind of gouging. Does it do it to rounds fed from both sides of magazine or just one side in particular? Blunt round nose bullets benefit from the M4 ramps more than the long tapered ones.

[Flewis]

Went through the brass last night and noted a few things about the gouged brass (new Winchester brass, 220 SMKs set at 2.170 oal, using PMags):

More than half were gouged, some more seriously than others, so it is happening on both sides of the magazine and ramps. I had a few, maybe 10 out of 50, that were unharmed.

The gouges match up with the top of the feed ramps.

I made up some dummy rounds and kept dropping the bolt on them, I never was able to replicate any of the gouges so something different must be happening when the bolt cycles during firing.

I'm going to shoot some this afternoon, so I should know more then.

[Flewis]

Well, it has something to do with the PMags. I have two 20 rounders... one causes more pronounced gouging than the other. The original 20 round GI mag I've been using (unmodified other than a Magpul follower) causes no problems.

Wasn't there a thread somewhere about people modding the PMags? Cutting out some area?

[pug]

One post was about cutting the ribs back so the rounds aren't forced towards the center of the mag. I have better luck with thermolds and the 20 round straight body c products mags.

[kdiver58]

I'm using a Case OAL of 1.360

My cartridge OAL is 2.170 to 2.180 using 220gr SMK bullets

It's funny how no 2 people have the same result with a M1S upper. I use Pmags with no trouble and 30 Round DPMS mags with only a few problems. Some people get a 3-4 MOA gun and others get a 1-1.5 MOA gun. It's all over the place.