Bushing size for 7mm Mag

[Scalloper]

I have did a search but I thought I would confirm. So, I have a 7mm Mag with a custom barrel. I have been reloading for many years but mostly using RCBS dies. I am considering getting a Redding S type die. My fired win brass measures .315 outside diameter on all 5 I measured. The inside measures .2845, .286, .285 I am shooting Berger VLD Hunting that measure .283"
First question, can I assume my chamber is .315"?
So I measured my loaded rounds at .308 ,.310 ,.308 ,.3095
Case thickness of .0145 ,.013 ,.013 ,.013
Again Berger bullet dia of .283
So if my calcuations are correct and I want .002th neck tension i need a .305 / .306 / .307?

 

[Fred B.]

Your chamber neck is mos probably.316.
No turn neck chambers are usually used with a neck expander since the neck wall is not consistent. For 2 .002 tension, I think you should try a .306 or .305 and use a .282 expander ball IMO.

 

[searcher]

I'd use .304 as a minimum as you may have brass .001" less than those measured and you will have .001" spring-back over time - leaving .002" tension. That would be about ideal for a target rifle. If your 7Mag is a hunting rig, I'd go with more tension, especially if loading off a magazine. then I'd use a .303.

 

[Scalloper]

I will be using it for hunting for sure. Thanks all