I'm using 180 Accubonds and have run a lot of tests using IMR 4350 H 4831 IMR 7828 and H 1000. I've been doing my tests from 55 - 65 degrees. I wanted to do my testing in temps from 30 -50 degrees but our weather went from sub 30's right to 60's. Unreal. I've also did a lot of off the lands testing ranging from .03 - .08.
IMR 7828 is winning out in my barrel. 76 grains with .03 of lands producing .637 in 3 shot groups and .04 producing .402 3 shot groups with average speed of 3110. SD has ranged from 3104 to 3122 but enough testing on this yet. I going to try .035 of the lands and change powder by .2 grain each way to see if I can get them any tighter but hard to beat .402 inch groups.
My questions/concerns my hunting temps will be mainly from 20 - 40 degrees. I have no knowledge on IMR 7828 temperature sensitivity. 50 - 70 fps loss is not a big deal in inches out to 400 but a little more from 400 - 600. I'm more concerned about how my groups will open up with that decrease in velocity.
Any body have any experience or educated guesses how many fps I might lose and how much groups might open up? Also I could be hunting at temps around 0 (not very likely) and if that happens I'm guessing I would have to limit my shots to 300 yards but just guessing. I will be able to do this testing next fall/winter but I have a NM elk hunt in mid October so asking because of this hunt.
