I'm in the process of getting some once fired .260 Lapua brass ready for reloading and I just noticed something odd that I need some advice on since I'm still a novice reloader...
When I measure the headspace (on the deprimed and cleaned) brass with a RCBS precision mic tool, I'm seeing that the headspace is varying anywhere from approximately .001" to .005" (rounding up where appropriate) above the '0' hash which is supposed to be the SAAMI spec of 1.630"; However, when I measured the brass again using a Hornady headspace comparator (D400) using a mitutoyo caliper, I'm see that it is all measuring anywhere from 1.628" to 1.630", which is either slightly below or just at SAAMI spec.
I do know that all comparator devices have tolerances built in, so I know that the results between the two tools won't always line up perferctly, which leads me to my real question which is:
How do I know which tool is giving the "right" measurement of the cases so that I can set my FL sizing die correctly? Do I skip resizing and just run the brass through my Sinclair neck expander mandrel to set the neck tension and just start loading (see second bullet point below)?
A little more information:
When I measure the headspace (on the deprimed and cleaned) brass with a RCBS precision mic tool, I'm seeing that the headspace is varying anywhere from approximately .001" to .005" (rounding up where appropriate) above the '0' hash which is supposed to be the SAAMI spec of 1.630"; However, when I measured the brass again using a Hornady headspace comparator (D400) using a mitutoyo caliper, I'm see that it is all measuring anywhere from 1.628" to 1.630", which is either slightly below or just at SAAMI spec.
I do know that all comparator devices have tolerances built in, so I know that the results between the two tools won't always line up perferctly, which leads me to my real question which is:
How do I know which tool is giving the "right" measurement of the cases so that I can set my FL sizing die correctly? Do I skip resizing and just run the brass through my Sinclair neck expander mandrel to set the neck tension and just start loading (see second bullet point below)?
A little more information:
- The brass is mostly once fired Berger 140 Hybrid rounds with about 10 pieces of what was virgin brass that I loaded with 40ish grains of H4350 (the hand loaded brass expanded more than the factory loaded rounds
- The random pieces of brass that I picked from each of the piles of various measurements all seem to chamber okay in my barrel, so I'm completely confused as to what the correct next step should be in order to get this brass ready for loading.
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