Over Pressure or no?

[SixPointEight]

I loaded some LC brass with 55gr Hornady SP bullets @ 2.200" COL. Loaded it with 1.6cc of AA2230 which is about 23.1gr, same load I use in my PMC plinking ammo with no worries. Manual lists 22.5gr-25.0gr as the loads. However, I let of 10 rounds, and on 4 of them I get what appears to be ejector smear. However...the primers aren't flattened, they aren't cratered, not flowing, backing out or blowing out gas. Then to top it off, the necks are a bit sooty like the round is under pressure.

Gun is a CMMG Carbine Upper with approximately 400-500 rounds through it. I have heard new guns can smear brass that's loaded within spec, but why only on some rounds? Could this be a false sign caused by marking it with the nail polish on the primer? I don't see how, but stranger things happen. Should I let the other 25 rounds loose and watch for more of them to smear? Looking through the brass, 2 unfired cases also have some minor smearing on them. Could it just be that these 4 had it before and I missed it, possibly.

Sorry about the dark pic, cell phone is best camera I have.

[Nessal]

Am i reading that correctly? Your oal is 2.200? Book spec lists 2.250. That would def raise your pressure.

[SixPointEight]

Cannelure and bullet manufacturer reccomend 2.200 COL. And I worked up to 25.0gr in pmc brass with no real pressure signs.

[freonr22]

different brass has different case capacity i think?

[Nessal]

Looking at those pics again. It does look like the primers are flattening. But the quality of you pics arent the best.

[freonr22]

http://www.calguns.net/calgunforum/showthread.php?t=227394&highlight=brass

[SixPointEight]

http://www.calguns.net/calgunforum/s...ighlight=brass

Perhaps that combined with the COL, and the fact that I measured volume not individual charge weight. I suppose it could lead to noticeable pressure changes.

I ought to chrono them to see where they're at. Next time I'll slow down the process and drop 1.5cc 2230, should put me around 21.0gr. But technically that's under spec. Or I'll save my LC brass for my nicer hunting loads and pull all my military brass from "plinking" circulation.

[Nessal]

Cannelure and bullet manufacturer reccomend 2.200 COL. And I worked up to 25.0gr in pmc brass with no real pressure signs.

I dont understand how a bullet manufacturer can list safe oal. How would they know what powder or grains you are using? You are better of using load data from the powder maker. Accurate recommends 2.230 for that powder with 55grn bullet i believe.

[SixPointEight]

Accurate does recommend that. The manufacturer was called and spoken with, and then I wrote an email to verify. Conflicting data, but, I'd be .030 off the cannelure loading that long.

"Josh, If you are planning to crimp the bullet, I suggest seating to the cannelure and roll crimp it. The difference of .030" will not affect performance in an AR-15 rifle."

Anyways, if you feel that .030" is making a significant difference I can pull the bullets a hair and shoot the rest of em.

[bohoki]

i noticed a couple of my loads i used the wolf primers had primer ruptures is that what i am seeing?

[SixPointEight]

i noticed a couple of my loads i used the wolf primers had primer ruptures is that what i am seeing?

All the Black? That's just nail polish. As to the belief that the primers are flattened, I can't get a decent pic of them, but they look exactly like factory PMC does after its been fired

[sonnyt650]

Could it be that these particular cases slipped within the chamber and slammed into the ejector bits instead of expanding normally to fill the chamber? What's your reloading procedure, does it include tumbling after sizing?

[bruce381]

weight your charge forget the CC stuff

[EOD3]

Bruce is right, you NEED a powder scale.

On the original problem, the LC brass typically is thicker and therefore has less capacity than the commercial brass.

[SixPointEight]

I have a powder scale. And I did weight check my loads, but I don't check EVERY throw. It takes forever because I don't have a trickler etc. Just the lee dipper set. So I weigh out 15-20 charges, and write down what they come out as. That way I know how much powder is actually held in the dipper.

Anywho, I'll just rework the load for LC brass