Finally found a time to shoot WITHOUT another cold front coming through, and at 88-92 degrees F, my 42.0 4064 load with 175 SMKs is STILL shooting 2530 fps.
With a different batch of brass but using WLRs, it was 2550-2580, 40-60 F. Then it was 2539 with FC brass and CCI 200s at 40 degrees F.
Later, at 70F, the FC/CCI goes 2549. Okay, 10 fps is within the "noise" but only 10 fps in 30 degrees shift is less than I expected.
Another 60F shoot gets me 2530. Another one, about the same.
Latest, checking zero after messing with the scope--2533 fps at 78-80F. Okay, 16 fps slower with the ambient temp 40F higher??? Isn't that within the variations people are getting with Varget?
This is ALL the same batch of powder, loaded the same day.
I've decided to bump the next batches up to 42.5, since it shoots just as tight and goes 2550, or with 178 A-Maxes in identical-capacity LC brass, 2558 fps.
With a different batch of brass but using WLRs, it was 2550-2580, 40-60 F. Then it was 2539 with FC brass and CCI 200s at 40 degrees F.
Later, at 70F, the FC/CCI goes 2549. Okay, 10 fps is within the "noise" but only 10 fps in 30 degrees shift is less than I expected.
Another 60F shoot gets me 2530. Another one, about the same.
Latest, checking zero after messing with the scope--2533 fps at 78-80F. Okay, 16 fps slower with the ambient temp 40F higher??? Isn't that within the variations people are getting with Varget?
This is ALL the same batch of powder, loaded the same day.
I've decided to bump the next batches up to 42.5, since it shoots just as tight and goes 2550, or with 178 A-Maxes in identical-capacity LC brass, 2558 fps.
