When I first joined here, before Grendel Vol. 1, I polled for favorite powders and 8208XBR was the most mentioned as relatively temp insensitive, so I ran with it.
6.5 Grendel AA brass
28.5 gn 8208XBR
123 gn SMK G7 BC 0.260, bearing surface 0.407"
2472 fps high
2464 fps low
8 fps ES
2467 fps mean of 5
3 fps σ
98°F 29%
28.53 4322'DA
20" 1-8.5 Krieger barrel, .264 LBC reamer
Hodgdon's online reloading data page lists 28.5 gn 8208XBR as a max load at 50,000 psi, but I stopped at 27.0 gn with the 123 gn AMAX:
6.5 Grendel
27.0 gn 8208XBR
123 gn A-MAX
2433
2397
36
2414
14
97°F 30%
28.59 4134'DA
The 123 gn AMAX is not listed in Litz's new Ballistic Performance of Rifle Bullets, but the allegedly "same" 123 gn SST has G7 BC 0.236 and bearing surface of 0.430".
6.5 Grendel AA brass
28.5 gn 8208XBR
123 gn SMK G7 BC 0.260, bearing surface 0.407"
2472 fps high
2464 fps low
8 fps ES
2467 fps mean of 5
3 fps σ
98°F 29%
28.53 4322'DA
20" 1-8.5 Krieger barrel, .264 LBC reamer
Hodgdon's online reloading data page lists 28.5 gn 8208XBR as a max load at 50,000 psi, but I stopped at 27.0 gn with the 123 gn AMAX:
6.5 Grendel
27.0 gn 8208XBR
123 gn A-MAX
2433
2397
36
2414
14
97°F 30%
28.59 4134'DA
The 123 gn AMAX is not listed in Litz's new Ballistic Performance of Rifle Bullets, but the allegedly "same" 123 gn SST has G7 BC 0.236 and bearing surface of 0.430".
