Making 8X57 Mauser brass from 7X57 Mauser?

[emcon5]

I have some 7X57 brass left over from a rifle I sold. Anyone ever necked 7X57 up to shoot in an 8mm Mauser?

I was thinking running a .30-06 expander stem through it once, to do an intermediate step, then full length sizing with an 8X57 die.

Is there enough material in the neck for this to work?

Thanks,

[kilimanjaro]

You can try it, but I think you will find moving the shoulder will work the brass a lot. Annealing would be in order, most likely.

I'd just scrap it or give it away and buy correct brass. Life is too short to waste that much effort for the return.

[F. Guffey]

I have some 7X57 brass left over from a rifle I sold. Anyone ever necked 7X57 up to shoot in an 8mm Mauser?

7mm57 to 257 Roberts works, 7mm57 to 6mm Remington works. 7mm57 to 8mm57 leaves the reloader with short cases from the mouth of the case to the head of the case. There is something about necking up and or down that drives reloaders to the curb. They believe the neck gets thicker and or thinner.

When I neck a case up the case neck gets shorter, when I neck a case neck down it gets longer, question, if that is true and everyone else is correct the neck gets thicker and shorter or thinner and longer.

I am not the fan of short cases, I want my cases to cover the chamber. there are cases I form that shorten .045" on wildcat chambers that have a case neck of .217". Reloaders are stuck with those numbers because they can do nothing about it, I use longer cases like the 280 Remington with the additional .051" added between the shoulder to case head.

When forming 7mm57 I go from 30/06 to 8mm57 to 7mm57. When the reloader takes charge of the length of the case from the shoulder to the head of the case they can offset the length of the chamber. Controlling the length of the case cuts down on all that case travel between the shoulder and head of the case.

Then there is neck cracks, the 7mm57 chamber has a generous neck, a few friends decided to chamber 7mm57 chambers to 280 Remington chambers. Made sense, both are 7mm, but the 7mm57 chamber neck is larger in diameter than the 280 Remington, when cases were fired in the modified chamber the cases were ejected with two different neck diameters.

Problem, all that travel causes work in the neck.

And then, the shoulder of the 7mm57 is behind the 8mm Mauser by .097". When fire formed the case body and shoulder is formed, what happens during that time is a source of confusion, when the case body and shoulder is formed the neck shortens (more)*.

* Meaning the neck shortened when it was necked up and it shortened when the shoulder/case body formed. Keeping up, the case length from the shoulder datum to the case head gets longer, the length of the case from the datum to the mouth of the case gets shorter. I am not the fan of short necks.

F. Guffey

[emcon5]

Thanks for the info.

Well, when I hatched this brilliant plan, in my head the cases were the same except for the neck, but after looking at the CIP diagrams of each, I figured out this much more involved than I first thought.

Looks like the shoulder starts ~2.3 mm and ends ~1.5mm farther back on the 7mm vs the 8mm Mauser.

That is a long damn way.

Looks like the better option is to buy another 7mm Mauser.....

Thanks again.

[Paul B.]

"Looks like the better option is to buy another 7mm Mauser....."

I can't think of a better excuse. Oh hell who needs an excuse.
I have three right now and may even build another. At least they do not give my arthritic should unholy hell like my big boomers do. Probably use one or my .280 Rem. an my next elk hunt.
Paul B.

[reynolds357]

My barrel should be here tomorrow to build my 7x57. Now I have to talk one of my buddies into letting me borrow a reamer.