I have been reloading for about 2 years. I have kept it fairly simple but I have recently purchased a Cooper in 280 AI and now that I have a gun that should be capable I want to try and get as much out of my handloads as possible. I had a load of 140 gr accubonds with cci200 primers and 59 grains of IMR 4831 with a coal of 3.380 (All that fits in magazine). I have shot groups of 1/2 to 5/8 of an inch (3 shot 100 yards) with this load in Feb. Went out today ( 31 deg C swing) and the best group I shot was 1 1/8 inch and velocity was avg of 2947 fps,5 groups shot all within 1/4 inch size velocity had max spread of 83 fps. I didnt have a chrono in feb so not sure of velocity then. I realize temp will have an effect on pressure and velocity but i thought i should be shooting faster in hot weather(disappointed in my velocity)? Is IMR 4831 very temp sensitive? Is it normal for temp swings to open up groups? What kind of loads are others using in their 280 AI's with velocities? Will my grouping return with coller temps? I also shot one group with 140 gr ttsx and 59 gr IMR 4831 coal of 3.340 its speed was better avg 3088 fps but group was 1.668. Any info and direction is appreciated.
Thanks
My own Coopers in 280AI liked 61gr of R-22 behind the 140gr TTSX. Velocity was 3140fps, with groups averaging just under 1/2". With 59gr of IMR 4831, and the 140gr TTSX, the velocity was just over 3100fps, and groups averaged around 5/8". The Accubonds were about as accurate, but I was using an extra grain of powder, but with similar velocities.
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Only accurate guns are interesting.
My own Coopers in 280AI liked 61gr of R-22 behind the 140gr TTSX. Velocity was 3140fps, with groups averaging just under 1/2". With 59gr of IMR 4831, and the 140gr TTSX, the velocity was just over 3100fps, and groups averaged around 5/8". The Accubonds were about as accurate, but I was using an extra grain of powder, but with similar velocities.
Are you using a magnum primer EH 11?
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Proper placement and Deep penetration are what’s important. Just like they taught in Sex Ed!
Elkhunter r u able to feed from the magazine when only .010 off the lands? Have u found RL 22 to be temp sensitive? I was thinking of trying it or RL 19 but have heard some bad stories. Sometimes there is to much info out there tho!
Cameron, you raise an interesting question. Feb. / July velocities. If you can shoot out of your back door put a few rounds in the freezer and chronograph them. Would legitimize your accuracy theories.
Another thought would be move the bullet in the cartridge just slightly. That would be just seat bullet deeper but only enough to break a seal that was forming.
Reloading question
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