8x57 Mauser "M" die for .303 Brit?

[DxF]

I've got a problem: I've decided to coax my No. 4 rifle (a 2-groove Savage) to shoot Montana Bullets' 190 grain spire point bullet, sized .315.

Yeah, I know, it's probably never gonna happen. But I'm stubborn... and like an idiot, I bought Lyman's M die for the .303, only to learn the expander plug mics .309. I'd like a plug that mics .313 or thereabouts (if a little larger I can patch).

.313 inch is 7.95 mm. I wonder if Lyman's M die for the 8x57 is worth a try? Or is there a machinist somewhere who could turn out a custom expander plug?

Or would .313 be too small? Maybe as much as .315... brass spring-back would be, what?

[MostlyLeverGuns]

NOE makes a push thru sizing die with many, many bushings. He does stock .314, .315, .316, .317.....

[Mk42gunner]

I don't load for the .303 British but do load for various other .30 and .31 cal rifles. Since I normally use a .311 or .312" boolit, I use the M die meant for the .32 S&W family of cartridges.

Whether it will work for your .315", I do not know but tis worth a try if you have one.

Something tells me the M die for the 8x57 will be way too large, nominal bullet diameter for that is .323" no matter what the actual conversion of 8mm to imperial is. You could get one and turn the diameter down in an electric drill and sand paper to whatever works for you.

Robert

[Hick]

I have used the same M die for my Mauser and My enfield. Sometimes it depends a little on the M die-- I have had to play with how far I screw the M die into the press, checking with a case as I go, until it is 'just right.'

[15meter]

You could look at the NOE "M" die inserts, they're designed to fit in a Lee belling die. I believe you can get very close to the exact size you are looking for.

I suspect the 8mm Lyman will over expand the case neck.

Here:

https://noebulletmolds.com/site/product-category/expanders/

[MostlyLeverGuns]

15meter has the right items from NOE for neck expanding, NOE carries 'M' style expanders, .316x.312, .318x.314, .319x.315 (step and expander diameter) plus a bunch more. I have quite a few and they work very well.

[DxF]

Thanks, everyone! The NOE inserts are on the way (and the Lee die). And you're right, the 8x57 tool is just too large. Lyman CS responded (!) to my query with this: "It will be .320 on the first step and .324 on the second."

[mehavey]

To be honest, the Lee Universal Flaring Die (https://leeprecision.com/universal-case-expanding-die)does it all -- all calibers.
Specific M-Dies are great, but get the Flaring die no matter what