FWIW....I have a 22" marlin xl7 with a pretty tight non freebore chamber. This spring I ran 60.5 7828 ssc under a 140 horn bt in 30 degree weather. The load clocked 2980. Was using a fed 210 primer.
When I put that load into quickload it thinks it should do 3053 at around 62k pressure but the standard setting is 70 degrees.
When I correct temp to 30 degrees it thinks I'll lose about 2ft per second per degree of temp change.
At 30 degrees the prediction is 2977fps at 58k.
Quick load doesn't get any better than that.
I'd hunt our normal wis deer season with the 210 primer cause we don't see temps like that. But if I really really was gonna be hunting in below zero I think I'd definately be testing the two primers against ea other for velocity and accuracy in cold cold weather.
BTW....from what I've read the fed 210 is probably closer to the cci 250 primer than a 200.
Thanks Don.
