I reload for 45. Recently picked up a new P220 in 45. I was loading a few mags at the range the other day and with my reloads and I could only get 4-5 rounds in each of my two Sig mags. I pulled the gun apart and all the rounds passed the plunk test in all my 45's. Rounds loaded fine in all other mags but the 220 mags. Factory ammo loads fine in the Sig mags. I'm baffled. Thoughts?