30 Carbine Case Bulge Near Head

[cipherk98]

I started reloading 30 Carbine today but had to stop due to quickly noticing a problem with my brass. All of it is bulged on one side near the case head, enough so I can feel it with my finger. This is present in both "raw" and resized/expanded brass. It still meets SAAMI specs for the dimensions of the case but it's a bit out of round.



It's a bit hard to see but there is daylight on the on the left hand side due to the bulge. I loaded a couple inert rounds that are just an unprimed case and a round and it chambers, goes fully into battery, and feeds fine, but I'm really concerned about this. I took the bolt out of the gun and put a live/new round in the chamber and it sits the exact same way as the reloaded, bulged round, and exactly like it should (ie the bulged spot isn't sticking out of the rear of the chamber).

What could be causing this, and is the brass safe to use? It's the same on my Aguila, PPU, and Federal brass, all shot from the same gun though it's less obvious on the Federal and PPU which do tend to come out of the gun cleaner than the Aguila, perhaps due to sealing better.

Edit: I'm asking on here as I've heard some inconsistent stuff on the net - some say it's normal and toss the brass, some say it's a headspace or chamber issue, others say the brass may be fine to reload, etc, so hoping to hear what people on here say.

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[Parashooter]

Completely normal. Brass fine for re-use. Poster seems unaware that cases have to be made smaller than smallest normal chamber - otherwise we can't get them in! Guess he's never heard of "tolerances".

Extractor forces chambered case to opposite wall, resulting in "out of round" perception. Actually, where expanded, it's just as round as the chamber.

There's plenty of real stuff to fuss about when handloading. No need to invent imaginary problems.

[Doco overboard]

Seems like the chamber has been mis -reamed or over polished I would think. Is this the first time you loaded for this particular gun or something that you just noticed after a recent outing or after a lot of previous use? Maybe a chamber cast could reveal more. Try to find out if the problem is with a particular portion of the chamber or random and dont measure the rim with your calipers while looking at the walls of the case, you may not have a problem at all.

[Doco overboard]

Didn't think about the extractor, thanks Para shooter.

[browningautorifle]

I agree that there's no problem and carry on sizing and loading. All will be fine after full length resize.

[Bruce McAskill]

The only thing to worry about with the 30 carbine is the case length. Once you have sized it then measure it to be sure it is less the 1.290 in length. Trim to about 1.285 which seems to be where most factory ammo is. If it gets too long it can cause an out of battery discharge which is not good for anything or anyone.

[browningautorifle]

The only thing to worry about with the 30 carbine is the case length.

Absolutely correct.

[TDH]

I can't argue with the case length and you can't make them to short either

[USGI]

You can't make them too short either

I'm not following you on that - seems to me like too short would cause some problems. Or, do you mean only a few thousandth's under specs? - Bob

[M94/14]

As most everyone else has said, your case looks fine. It's simply the product of a slightly large chamber, and nothing to worry about.

On the subject of reloading...It seems that most reloading manuals specify 1.280" as the trim to length. That is fully .010" shorter than the minimum headspace dimension of 1.290". That's a lot of Headspace by any account, even though it appears to not cause any functional problems in most carbines.
It is well known that brass flow in .30 Carbine cases when sizing is particularly bad, and repeated trimming due to forward brass flow will contribute to premature case life due to eventual head separation. For once fired cases, I will full length size and trim to 1.285". For subsequent loading's, I will run the cases into the full length sizer measure the case length, and adjust the die depth until that 1.285" dimension is reached then stop. My cases still have enough tension to hold the projectile firmly.