Using the barrel (out of the gun, of course), put a straight edge across the standing breach and use a feeler gauge to measure the amount the case head is below the breach.
Once you've established this data point, set your sizing die to move the SHOULDER back to achieve this head space.
I, personally, go for about three thousandths. But, your milage may vary and you're really on your own because there is no data for determining head space in the way I've described.
Start with some factory rounds -- which have generous headspace -- and work down to a lower figure that allows the pistol to run reliably. Factory headspace is set to allow the pistol to continue to operate when very dirty. Something that most of us don't do and would never do with reloads in practice sessions.
(parenthetically, you'll note a WIDE variation of headspace on various brands of factory ammunition. This suggests -- to me, at least -- that factory rounds are also using the shoulder to headspace the round.)
You may (on certain brands of dies) have to shave the shell holder or bottom of the sizing die to achieve a proper head space. This is the situation with RCBS dies in my experience.
If anybody has (finally) produced an head space gauge in this caliber, it's news to me.
Since there is so much confusion within the industry about how this round actually functions as a reload, it is not surprising no one has produced a gauge to verify "truth". That is moot, of course, because you have the actual barrel at hand, which is the best gauge you could hope for. After all, that's the gun the ammo has got to run in.
Once you've established this data point, set your sizing die to move the SHOULDER back to achieve this head space.
I, personally, go for about three thousandths. But, your milage may vary and you're really on your own because there is no data for determining head space in the way I've described.
Start with some factory rounds -- which have generous headspace -- and work down to a lower figure that allows the pistol to run reliably. Factory headspace is set to allow the pistol to continue to operate when very dirty. Something that most of us don't do and would never do with reloads in practice sessions.
(parenthetically, you'll note a WIDE variation of headspace on various brands of factory ammunition. This suggests -- to me, at least -- that factory rounds are also using the shoulder to headspace the round.)
You may (on certain brands of dies) have to shave the shell holder or bottom of the sizing die to achieve a proper head space. This is the situation with RCBS dies in my experience.
If anybody has (finally) produced an head space gauge in this caliber, it's news to me.
Since there is so much confusion within the industry about how this round actually functions as a reload, it is not surprising no one has produced a gauge to verify "truth". That is moot, of course, because you have the actual barrel at hand, which is the best gauge you could hope for. After all, that's the gun the ammo has got to run in.
