Gun is a 620. Load xtreme 148 over 3gr Tight Group. All was fine until the round rount got north of 200. The gun was rather hot and I started noticing ouffs of smoke...like the kind you get with lead...I used taper crimp inly with these.

Here's what the recessed crown looked like after shooting:





Yes, that is lead.

Here's what a 620 crown looks like clean for comparison:



How did I manage this?