just a thought, did you double check your powder charge?

by Brian A, Thursday, October 22, 2015, 20:27 (3323 days ago) @ Fowler

I know I have set the powder drop up thinking of load x and got distracted and had it dropping a different charge. Seems the most likely sinerio, pull a bulletin a remaining round and make sure of your charge weight.

Since these are the first 357 mags I loaded this go 'round, I fiddled with the measure quite a bit to get it throwing correctly. My press is an old Dillon 450 with the original measure that is a bit temperamental to adjust accurately, so each of the first few rounds gets weighed, than each 10 until I'm satisfied it is throwing properly. None of those measured from these 12 rounds varied by more than +/- 0.1 gr.