magvance, I think you are going to get a confusing mix of answers on this one. The answer may not be completely clear as many factors come into play on this question. Ambient Temperature will make a difference as will the amount of powder you are using in the case. Another factor will be the individual lot# of the primers you are using. I read an article some time ago on how one manufacturer did an exhausting test of all available primers in an effort to catalog the coolest to hottest burning of the mix. After establishing a rating, more primers were purchased and one of the coolest of the last bunch turned out to be the hottest of the new batch. This is the crux of the problem for many when trying to answer this question.
Same goes for different lot #'s of powder.
FWIW, Here is how I do it. I load with mainly ball type powders and as a rule have found for *MY* loads that Magnum primers work the best as far as accuracy and velocity are concerned. I do though live in Taxconsin where most of my hunting is done in weather below 30 degrees. I do shoot though in warmer temps and have not run into any pressure problems with *MY* loads because of the temperature increase during the warm weather months.
If I find a load I like, I purchase a thousand primers of the same lot number and the majority of my powders are purchased in 8 bl. containers so as to alleviate the lot # problem from cropping up with the powder as well.
As always YMMV, and remember my opinion is as irrelavent as the next guys
..............Chainsaw