Home Forums Reloading Big Game Rifles 270 Win H4895 Reduced Load

Update:

From Lee's "1-gr reduction" values for IMR 4895 in 270 Winchester, I ran through the algorithm and arrived at 30.5 grains IMR 4895 (130-gr bullet) to target ~2200 fps. The max load to reduce from was 46.9 grs (2957 fps), so 30.5 was 65% of max charge. Yesterday I shot 10 loads, and clocked 5 of them, which averaged 1943 fps, or ~ a 66% of max velocity of 2957 fps.

So the Lee approach overshot the velocity reduction. Of course there are many other variables like powder lot, seating depth, primer, temperature, chamber/bore dimensions, case capacity, etc.

Using my results, I estimate that 34-35 grs IMR 4895 will get me closer to 2200 fps. TBC. (I.e. close to 75% max charge to get close to 75% max velocity, which is what some chaps here have said all along, that the charge/velocity ratio was near 1/1 or linear.)