12-31-2021, 10:25 PM
Personally, I fire-form my x39 brass by using my standard x39 brass based load I have seen no meaningful difference in performance or pressure sign just running it as-is, even if not fireformed yet. As reminder though x39 in general should be a weaker charge than 6.5Grendel loads (thicker wall construction so smaller volume in x39 casings, even after fireformed).