Kirby, it is my belief that cold weather even really cold weather effects BH-209 any worse than any smokeless powder. I do not believe it is the powder that might cause the problem.

I believe the problem exists in how cold the metal is in the ignition area. Often, and this has been my experiance, so much heat is lost by the ignition source in warming the metal on the way to the powder that enough heat does not arrive at the powder to ignite it in the cold barrel.

I hate to use Jim Shockey as an example.. but he has faced this same problem in some of the cold weather arctic type hunts that he does. His cure is that he wraps the breech area with a hand warmer while hunting. Not sure I would take it to this degree.. but I would certainly give consideration to heat loss due to being absorbed by surronding metal.

Using a hotter ignition source may solve a lot of the problems if there is a doubt and having a breech plug that will deliever the flash to the powder in a timely manner without obstruction is certainly important. Use a BP with a clean flash channel and have a breech plug that can breath and direct the bulk of the flash to the flash hole without delay.

Nothing replaces your own personal testing...

Just my thoughts...