20BR with 55 gr bullets
I've got a BAT 20BR-IMP with 1:9 PacNor
Playing with the 50 grain bullets I've found that any powder faster then
N540 isnt going to be consistent. I've never actually shot N540 so had to substitute with H414, W760, and H4350 (tried IMR4350 but it wasn't accurate)...H4350 was 3 shot group in low .2's @ 200 yds.,
I havn't settled on any one powder, still going to do more work.
My velocities are being kept @ 3800 fps to maintain case longevity.
Problem is that accuracy improves with speed.
start lower & work up...as usual
H414 > 34.4 gr. 86% case fill @ 3,796 fps
H4350 > 33.9 gr. 90% case fill @ 3,817 fps very accurate
W760 > 35.4 gr. 91% case fill @ 3,850 fps (need to reduce powder/velocity)
Your 55's might really like any of these powders.
These powders were from 85-90% case capacity...with low ES and SD
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