I was just load testing Re-17 in my 6mm Rem (24" barrel) Reunning 90 gr. Speer SP/FB's up to 3500 fps. I started with the load I normally use for the 95 gr. Berger which is 45.5 gr. of H4350x. So, starting at 45.5 and working up in .2 gr. increments of two cases each level. I went up to 46.7 gr. The lowest load produced 3325, and the next load was 3360. 45.9 produce 3450 avg. 46.1 gr. went 3505/3515. All the way up the groups stayed at 3500-ish. The powder does as advertised and retards burn when pressures get too high. I never did notice flattened primers. They had the little cratering 'splash' but no flattening. Maybe the CCI primers are harder than the Win LR's I've used for so long. I plan on starting a starting load of 44.5 for the Berger 95 gr. VLD's.
Long and short of it is, in my mind, 3500 is too fast for 90 gr. Speer flatbases out of a 6mm Rem or .243. But the loads didn't show pressure signs. The best accuracy came from the 46.1 gr. @ 3450. So, even though the burn retardant is integral throughout the powder instead of just coating the kernels, it still tends to go erratic once you pass a threshold. Groups were typically side by side with the 46.1 group touching, to 1.5" on the last couple. One ladder doesn't tell all but that tells me enough about going too high with the load.
Long and short of it is, in my mind, 3500 is too fast for 90 gr. Speer flatbases out of a 6mm Rem or .243. But the loads didn't show pressure signs. The best accuracy came from the 46.1 gr. @ 3450. So, even though the burn retardant is integral throughout the powder instead of just coating the kernels, it still tends to go erratic once you pass a threshold. Groups were typically side by side with the 46.1 group touching, to 1.5" on the last couple. One ladder doesn't tell all but that tells me enough about going too high with the load.
