I've recently switched powders, from AA#5 (which I liked quite well) to HP-38 as I was able to buy an 8 lbs jug on quite a deal. I worked up a load near the tail end of summer that shot well. Seemed to be about mid-power levels and cycled everything I had reliably. I then started building an AR and hadn't shot the .40's in a little while. Cut to this weekend. Ammo is stored in the garage and it's roughly 36 degrees outside. Take ammo to outdoor range, and suddenly 80% of my shots result in a stove pipe of the ejected brass, or failure to eject at all. Recoil and the report is also noticeably less than before. I loaded about 400 rounds with 5.5 grains of HP-38. Shooting 165gr Berry's Plated. Starting loads according to my manual should be 5 grains - 5.8 grains max. At 5.5 grains in the summer it was shooting great. Is this the cold weather performance I should really expect? I'd rather not pull 400 rounds and move up to 5.8 grains. Should I increase my crimp to help build more pressure? I'll verify how deep they're seated right now, but I'm on a Dillon 550b and haven't had to modify that since I initially set it. It's been rock solid whenever I verify OAL randomly. Any tips would be appreciated.