Belted case headspace
Q I read your reply to another reader about how to maintain minimum headspace with belted cases. You recommended that he buy a neck-only sizing die to prolong case life. Could you elaborate a little on this?
Michael White
A I think I have already dealt with this subject, but here goes. Chambers for belted cases usually have generous dimensions up front because the belt is intended to stop any forward movement of the case, but alas, the shoulder isn’t always a close fit in the chamber.
Standard minimum headspace for H&H belted rounds is .220” (5.59mm), with the no-go gauge measuring .224” (5.69mm).
Repeated firing and sizing of belted cases in long chambers usually produces a white ring just ahead of the belt. This ring indicates there has been thinning and hardening of the brass there. If you insert a bent wire and slide it up and down along the inside of the case you can feel a groove at this point. This case stretching and thinning leads to early case failure, but can be avoided by neck sizing, which allows the shoulder to stay in contact with the shoulder in the chamber.
Neck sizing makes a belted case headspace on the shoulder like a rimless case, reducing stretching and prolonging case life. Of course, after three or four reloads cases will need trimming and full-length sizing, but if you gradually adjust the die down a bit
