8mm RM brass to 7STW ?

[RH300UM]

300 bee = 97.5 gr. H2O in Weatherby brass 3x fired
300 WM = 94gr H2O in Winchester brass 2x fired

according to my reference books, volume of weatherby 300mag = 137gr H2O ; Winchester 300mag = 116gr H2O

 

[brewster29]

Got my hands on some 8mm RM brass . To make it 7STW is it as simple as lubing it and running it through a full length sizing die, or are there other steps ? Need a little advice from someone with experience . Thanks in advance.

That's exactly what Laine Simpson did back in the late eighties to get the 7 STW started. That's also what us old timers had to do until 7 STW brass became readily available. It's an easy operation and I never lost a case doing a couple hundred of them.

 

[Tidesloe]

Many of you guys probably already know, but ADG will be producing 7STW brass this year. It will likely not be easy to get initially, but there will be quite a demand for it.
I've never necked down from 8mm, but I'd probably step the neck down a time or two before running it through an Fl die, then run the correct size mandrel in it and then neck turn.
I would definitely anneal maybe a couple of times through that process. That's a lot of work on the brass. Just my thoughts on it

 

[Jim’s Hunt]

I like all of this neckiofown stuff

 

[Jim’s Hunt]

I like all of this neckiofown stuff

This was not meant to be sent. I wanted to say I love this necking down stuff but by all means get some Redding imperial die wax. It will make the job a little easier

 

[dogz]

That's exactly what Laine Simpson did back in the late eighties to get the 7 STW started. That's also what us old timers had to do until 7 STW brass became readily available. It's an easy operation and I never lost a case doing a couple hundred of them.

Correct, we also made 340 Wby brass out of 8 RM as well

 

[WapitiBob]

I'd just buy some of the available Nosler brass and not fiddle with necking down.

 

[brewster29]

Except then you have Nosler brass. I have been very unimpressed with the stuff I have used.

 

[Tidesloe]

Nosler brass is ok, if your not stepping on it too hard, but ADG coming out with it this year will breathe new life and interest in this great cartridge.
Necked down 8mm would probably be better brass than Nosler though

 

[8x68s]

I'm afraid that's way out to lunch, not even the 30-378 weatherby has 137 grains h20 capacity. The 300 weatherby is right around 100, and the hornady cases I measured, when filled only to the shoulder neck junction, measure around 94-96 grains of water (not exact certainty)

yep, I read the wrong reference. According to Ken Howell, "Designing and Forming Custom Cartridges", he calculated 133gr of H2O. I read thru his measurement techniques and found that his numbers are estimates derived from his use of Autocad when drawing cartridges for his book. He didn't actually fill cases with water and weigh them.

 

[Jim’s Hunt]

Except then you have Nosler brass. I have been very unimpressed with the stuff I have used.

High pressure load like the STW primer pockets would maybe last 3 loading in Nosler. I've used it twice. First and last time

 

[WapitiBob]

High pressure load like the STW primer pockets would maybe last 3 loading in Nosler. I've used it twice. First and last time

I'll get at least 10 out of my current combination, 81.7gr N570.

 

[LouisianaHunter]

Nosler brass is ok, if your not stepping on it too hard, but ADG coming out with it this year will breathe new life and interest in this great cartridge.
Necked down 8mm would probably be better brass than Nosler though

Well the 8mm I have is Nosler . Do have the imperial wax . We'll see

 

[HRM Johnny]

It might be a good idea to just snack down a few of the cases. Shoot them. See how long the case life is. See what kind of accuracy you get. Just my two cents.