09-24-2021, 01:36 PM
You didn't say how many times the hornady's were fired, but from my experience either the lip of the case mouth hit the internal die stop or shoulder bumped up hard against the die shoulder, something to crunch down the neck like that.
(One more thing occurrs to me) - you should probably resize and trim the grendel down to in-spec first, before doing any sizing down to the 6Arc. Sometimes a grendel chamber can leave the case quite long after firing... I have had shoulders up to ~1.227 after firing from a loose chamber (I got rid of that barrel but it happens).
Couple of options I can think of, but first make sure you trimmed the oal down to at least 0.030 below the grendel (1.520 max for grendel case, 1.490 for the 6Arc case).
Then do the resizing. The neck-down will push some brass up into the OAL of the neck so go a bit under the 1.490 for the trim.
Annealing first is a definite help (I'm still learning that art), other thing might be to bump UP the resizing shoulder distance in your 6Arc die. IE, it's set now for the 1.186 or so shoulder height, whereas the grendel case is more like 1.215 give or take... so raise your 6Arc resizer up to ~1.200 for a first run, then back it down to the 1.186... do the effort in two bumps not 1.
Anyway, a few thoughts to think about...
(One more thing occurrs to me) - you should probably resize and trim the grendel down to in-spec first, before doing any sizing down to the 6Arc. Sometimes a grendel chamber can leave the case quite long after firing... I have had shoulders up to ~1.227 after firing from a loose chamber (I got rid of that barrel but it happens).
Couple of options I can think of, but first make sure you trimmed the oal down to at least 0.030 below the grendel (1.520 max for grendel case, 1.490 for the 6Arc case).
Then do the resizing. The neck-down will push some brass up into the OAL of the neck so go a bit under the 1.490 for the trim.
Annealing first is a definite help (I'm still learning that art), other thing might be to bump UP the resizing shoulder distance in your 6Arc die. IE, it's set now for the 1.186 or so shoulder height, whereas the grendel case is more like 1.215 give or take... so raise your 6Arc resizer up to ~1.200 for a first run, then back it down to the 1.186... do the effort in two bumps not 1.
Anyway, a few thoughts to think about...