OK, we all know that higher air/rifle/propellant temperatures increase pressure. For maximum safety we would do all our load development on the hottest days of summer.

Not only is that unpleasant but it is a long way off. In the meantime, we are having a prolonged cold snap (by DC standards) but the wood stove at my gun club range house is nice and toasty, and deer season is over.

So, how much cooler will you tolerate for working up loads?

By the numbers: daytime highs this weekend not expected to go above 35 deg. F. My next two planned hunts are for pigs in central CA in April (avg. daytime high 58 deg. F) and pronghorns in NE New Mexico in August (avg. daytime high 84 deg. F). I hope to work up a pronghorn load I can practice with all summer in VA and MD -- avg. daytime high unspeakable.

John

It depends on the powder. I've worked up loads in the wintertime, with temps in the 20's, and then fired the same loads during our high summertime temps of the 70's and the velocity increase was only 20 fps, that was RL 15.

I would be concerned if I worked up to max loads in the winter, and then fired them in hot summer temps. If I were 1 gr or more under max, and that was the most accurate load, I'd be done with it, and not worry about things.

Where folks get into trouble is working up hot loads that appear safe in the winter, then fire them in hot summer temps. There are good reasons for heading max loads, and staying under them if a all possible.

This is a concern to me also. It's -6 in the day lately but it's unseasonly warm. -10/15 is what to expect.
I won't load above book max. before the spring time. Spring time will produce simmular conditions to hunting season and I will fine tune then.
Summer time I will load a practice round to keep sharp that I can afford.

John... this is great topic! I live in Az where my summers are oftan 110'F. For Rifles and loads I have not accounted for I do all of my load development in the summer. It is oftan to hot to hunt in the summer anyways. Also we get restrictions in some areas just to access because of fire danger. Now here is something I have found... even though I may load in the summer at 110 deg, in the cooler months I see very little change in velocity IF the load is near max. This is just my observation.

I planned on working up .338 and .220 loads today but I woke up to 0 degrees F . I did some load testing the other day with IMR 4353 at 20 degrees and my load that seemed same is apperently over max. 32 degrees and warmer I don't worry about.