Powders are all different. I noticed someone mentioned muzzle flash. I remember loading a light bullet in my 243 Winchester using BL-C(2). That powder lights up the night if you touch one off in the dark. Even legal shooting hours at dusk it will fill your scope as KDM mentioned. For law enforcement they load special low flash ammunition.
svnmag I understand what your asking. Hodgdon extreme powders help, but they don't do as much as advertised. You need to do a lot of chronographing in winter to know that. I have chronographed at 20 below zero. As a matter of fact I waited for 20 below zero. When I was younger I preferred hunting in cold because the coyotes are very hungry.
Ball powders are notorious for loosing velocity in cold weather. In some of the older Speer reloading manuals they recommend magnum primers for ball powders. I shoot a lot, so like ball powders that don't require trickle charging for an accurate powder dump. So what I did back years ago was build cold weather and warm weather loads. I would paint my primers red for warm weather, and blue for cold weather. If I remember right there was about a grain and a half difference in my 20 below load and my 80 degree load in my 22-250 with 50 gr bullets. Today I build my loads in warm weather and enter the temperature into my program before hunting. Sometimes I would watch the weather forecast and print of a small cheat sheet the night before hunting.
