Ron, This seems informative. With quick reloading @ -7 F, I know your barrel isn't getting "warm", but it's likely getting "warmer" than -7 F. It's possible the small ribs on the Crush Rib are more susceptible to change with temperature.

This article takes up the topic of load effects on 50/44 sabots. Temperature is known to affect plastic. I wonder if 50/45's are better than 50/44's at low temperatures or across wide temperature variations?

I took a deer at -5 F temperature this past season with a 50/44. Load development was probably done in 40 - 65 degree temperatures. It went where aimed, but that was 125 yards, not 200.

Bill