How to convert 7mm Mag brass to 264 Win mag

[RyanG]

Ok guys I need some help in changing 7mm Mag brass to 264 Win mag brass.

From my understanding I need to run the 7mm through the 264 dies twice. The first time with out the decapping pin in the die. Then a second time with the decapping pin in. Is there anything else I need to do.

Of course I will have to trim, but am I on track here?

Thanks

Ryan

[KRP]

What's the purpose of running them through the die twice? Unless they come out too long for the chamber I wouldn't trim until they are fireformed.

[darkker]

1) Lube
2) FL sizer die
3) trim
4) load and shoot

[RyanG]

Well from what I can tell from looking at the two casings they are the same except for the neck. I was thinking that by running them through the full length sizing die without decapping pin the first time would stress the brass the least. Maybe I am wrong... but trimming them to length after they are sized needs to be done I think.

[KRP]

I personally would only size them once, and only partially at that. I'd leave a false shoulder to give a nice snug fit in the chamber and minimize stretching the cases. I wouldn't trim until after firing unless necessary, as you'll end up doing it again to even them out. They'll grow in length slightly necking them down but it's quite possible they'll be short from the start.

[stangfish]

If you have a hornady case headspace gauge, use it.

[scope eye]

Ryan I always resize my brass in multiple steps, I find that they come out nicer, it's not like you have hundreds to do, resize one of each side by side and you be the judge.

Tanks Dean