Head Space for a 6,5x57R

[Bluejay]

Hello Gents,
I am reloading a 6,5x57R (Rimmed) caliber using NOSLER 120 grs. Ballistic Tip (awaiting for the AccuBond ) and I would like to know what head space I should be using, to get an accurate and safe cartridge.

I am using a K95 Blaser single shot, which has a 8" rate of twist and very long free boring and, for this reason, I decided to move form the 100 grs. Ballistic Tip to the 120, since I think the lighter bullet, due to the mentioned long FB, can not touch the rifling before completely leaving the case, thus not giving the accuracy I am looking for.

I do not have this problem with the 120 grs., being a much longer bullet.

Thank you in advance for your precious advices.

Regards
Bluejay :wink:

 

[Bluejay]

Forgot to mention: for those of you not too familiar with this caliber, I can say it's very similar to the .260 Rem.
Thus, I think same rules apply....

TY

 

[Ol` Joe]

Headspace is the slop fore and aft in the chamber/case fit. The measurment you want, I believe, is the distance off the lands to set the bullet. This is something different in each rifle, and the only way to know what ones rifle shoots best is to run a few rounds of various lenght through your rifle and see what lenght it seems to prefer.
I start by working up my load at the lands and backing back off them in 0.005" increments and fireing 5 rd groups at each lenght when I reach max.