Significantly overtimmed 7.5x55 brass

[Peregrine]

Hey all,

I accepted some free for the price of shipping 7.5x55 brass (x50) that someone was offering on a forum, they received it in a trade with a rifle and never actually did anything with it themselves.

Older PPU headstamp, generally it looks quite good but someone trimmed it way too much. Trim to length in the literature i've found is 2.185" or 2.175"

This stuff measures 2.094", I can only assume someone misread something and took off an extra .1", unless someone has a better explanation. Interestingly that someone did a pretty good job processing it at one point, the necks are nicely chamfered and the primer pockets are so clean you could eat off them, it was just just tarnished from age. I gave them a quick soak and a tumble and they they look quite nice.


I'm quite short of boxer primed brass for this caliber (only have 40), i'm curious as to what would happen if I were to use it. I'd imagine with the decreased neck area the pull force would be less and there'd be a significant difference in powder burn and the pressure curve compared to proper length brass. But what else would I be inviting here?

Here's a picture of two of them sitting on either side of a regular GP11 case, this is before I cleaned them. Ignore Dr.Peterson in the background.
They look a bit comical.

[RED BEAR]

Is it possible they were going to convert it to something else?

[ascast]

I would shoot them with out concern, maybe a different POI slightly. Looks like the groove for the rim has been turned a bit.

[Peregrine]

I would shoot them with out concern, maybe a different POI slightly. Looks like the groove for the rim has been turned a bit.

It would appear so from the picture if you look at the one on the far left. But that's just an odd quirk of the light, the groove doesn't actually look that was in person. The angle from the major diameter of the cartridge down to the bottom of the groove is constant, no step there. Just an illusion.

[georgerkahn]

My thought is with any RIMMED case, a tad too short won't hurt a thing, as long as the published over-all-case-length is what, or close to, what is published. If the bullet is seated "normally" in the short case, the pressures RISE! How much? I do not know, but I've read enough tales of blown up receivers to more than outweigh those remarking it makes little or no difference.
I do not know of the firearm you intend to shoot these in, but if the case rim determines headspace, you may indeed be in a situation with possible not-so-good an outcome. If it were me, bion, I'd ring one of the ballistic technicians on the Sierra hot-line -- 800-223-8799. My experience with off-the-wall queries not too dissimilar from yours have yielded most knowledgeable, friendly advice.
BEST!
geo

[Dan Cash]

You may well experience leading if you are shooting cast from those cases but jacketed should offer no problems. I wish those rifles were chambered for .308, 7 or 8mm Mauser or .30-06. The guns are so nice but the cartridge, although a very efficient one, is a freak.

[country gent]

As long as the extra trimming wasn't to hide cracked necks or other flaws they should be okay. Load to same oal as normal brass. You will have a little less neck tension and getting good concentricity may be a little harder with loaded rounds. But as long as you maintain the oal pressure shouldn't raise. The big issue is you may have chambering issues thru extended sessions do to a carbon build up in the neck area of the chamber.

[smoked turkey]

Shooting with shorter brass when loaded to the listed COAL shouldn't present problems considering it is done quite frequently with the 45-70 Hornady brass that was originally loaded with their LeveReveloution ( or how ever it is spelled..).