OzFclass

I have a .312 neck chamber and need to neck turn brass to suit for a 7mm, does anyone have a view on how much clearance to leave between the neck and chamber?

I was thinking with a .284 bullet + neck thickness of maybe 12.5thou to give 3thou total/1.5thou all round, or does this sound a bit tight? This is for an F Open rifle similar to a 7mm SAUM but with a different shoulder angle.

Cheers

3+thou is fine
I run .312 reamer case loaded .308
I believe that the larger 7mm cal prefer a little more clearance than the 6mms
Cheers
RB

Yes, .003" is what I have switched to in my 6mm and 7mm.
.002 or tighter gave problems with verticle. (occaisional velocity spikes)

Three thou it is then, many thanks for your replies.