It is about 59 F here now and during the hunt it may very well be -15 F or less. This is one of the reasons I did not want to use RL22. Given what has been said here I think I will try a few different powders and report back after testing at the range.

With respect to MRP, and other Norma powders for that matter, I have contacted the company that is listed on Norma's web site as the Canadian distributer and was told, about MRP, URP and 204:
Quote
we dodn't carry those items.