Re: .223 lapua brass breaks in half
Laffin' here big time. While I'm not the oldest participant on this forum, I've learned enough that I've got two ears and one mouth and should use them proportionally. OilyOwl/NOBODY/adfinitum... has it right in this instance and while you may not like the way it comes across, I've learned from experience when I received my first flame posting from said individual years back that as a newbie here it would be best to keep quiet and read until I gained the expertise to then share. I realize you've been reloading for some time, but frankly, we all miss some details along the way and run into issues that serve to only hone our craft. Chalk it up to experience of which I look forward to gaining more (and giving back) each day.
That said, here is my prescription for testing this empirically to see if you indeed have a headspace issue. Load up a few pieces of virgin brass and skip any resizing whatsoever (just uniform the primer pocket, trim/chamfer/deburr the case mouth, load it up and shoot it). Save the brass as your test "specimens" and mark the baggie for reference later.
Now go buy the appropriate Sinclair bump gauge and bump gauge body
Sinclair bump gauge and measure the fired cases. Take note of the measurements and determine an average.
Once that is complete, go back and measure a few of your already reloaded cartridges that have been bumped. Take note of measurements again and determine an average.
Compare the measurements. The measurements from your test specimen brass will show you the true measure of your rifle's headspace. Check and see if you indeed were bumping the shoulder to far and report back.
When you setup your die, adjust it to bump only .001"-.002" and lock it down with a locking ring.
Done. No more headspace separation worries and probably a more accurate rifle to boot!