30 Carbine Case Bulge Near Head

[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.

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]

. . . 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.

Unless I'm mis-reading, this appears to advocate partial sizing. If so, that's not generally a great idea for self-loading arms. Should an over-large case stall while chambering, an out-of-battery "slamfire" may occur. Complete F-L sizing can help prevent this rare but serious consequence.

[browningautorifle]

this appears to advocate partial sizing.

Seems to. I'd FL resize too, never had any problems that way and bullet retention was always correct.

[M94/14]

Unless I'm mis-reading, this appears to advocate partial sizing. If so, that's not generally a great idea for self-loading arms. Should an over-large case stall while chambering, an out-of-battery "slamfire" may occur. Complete F-L sizing can help prevent this rare but serious consequence.

Yeah, now that I think of it, not the best advice to have given a new handloader. I can get away with that procedure because my sizing die is a bit on the small side. The O.P.'s die may not be.

[USGI]

Yeah, now that I think of it, not the best advice to have given a new handloader. I can get away with that procedure because my sizing die is a bit on the small side. The O.P.'s die may not be.

With your dies, is the benefit of your "procedure" that, as long as the cases are all from the same lot and fired from the same chamber, the rest of the cases won't need checked for length after sizing? I can see where that might work. I just went out to the shop and checked a bunch of "emptys" of various headstamps and fired from two different carbines. I found case lengths to be anywhere from 1.273" to 1.296" - a lot of variation, but when I picked out a few that I know were from the same lot and fired from my own carbine, they were fairly uniform in length. I can see where you might save a lot of effort on the resizing with that method too; those tapered cases can take a lot of force to FL resize. - Bob

[M94/14]

With your dies, is the benefit of your "procedure" that, as long as the cases are all from the same lot and fired from the same chamber, the rest of the cases won't need checked for length after sizing? I can see where that might work. I just went out to the shop and checked a bunch of "emptys" of various headstamps and fired from two different carbines. I found case lengths to be anywhere from 1.273" to 1.296" - a lot of variation, but when I picked out a few that I know were from the same lot and fired from my own carbine, they were fairly uniform in length. I can see where you might save a lot of effort on the resizing with that method too; those tapered cases can take a lot of force to FL resize. - Bob

Hi Bob

Actually, the reason is that my sizing die is smaller than what would be termed a small base die, it is more like a production die. If I set it so that the shell holder touches the bottom of the die, it will size my previously trimmed brass (all from the same lot) to over 1.290". So, I back off the die as necessary until it sizes the cases to 1.285". Bullet retention is solid with no setback during firing. The side benefit, was that measurement of subsequent sizing's of those same cases after firing showed that they would all size back to between 1.284"-1.287" for at least the next 3 loading's before trimming was necessary. I use the same load all the time, so I don't get many dimensional anomalies.

*Disclaimer to all*

Please understand, I don't advocate anyone follow this procedure, I only explained it because it has cut back on how often I have to trim cases. That is the main benefit. This works for me, but may not work for anyone else. If anyone disagrees with this, then just do it the way that works for YOU. The bottom line, is to know YOUR equipment.