I'm north of Dan B and it is cold here too. I just started working with a 243 in a Ruger rifle. Sorry it's not a pistol. My brother and I shoot an informal rifle league during the winter. I would be using the XP to show the rifle boys how it's done but it's all apart as I'm fitting an HS Precision stock to it. Ran into a snag so it's on the shelf for a little while. Anyway, I'm using the 80gr Sierra Blitz and 35gr of reloader 15. Accuracy is ok. Groups are close for 3 or 4 shots and then one will fly out 2 inches or more. The necks are tight when I check a loaded round in the flyer case. I Micked the necks and they don't seem to be thick. Have been checking chamber dimensions and think I have a short neck area as there are marks on the rim of the case. OAL is under specks. Very frustrating. But I will figure it out. Thought about getting some serosafe (sp) and casting the chamber.