QuickLOAD, set for 68gr Berger, loaded to touch rifling, with .180 of bullet shank,bearing surface) in neck, with a 63,000 psi max load, predicts roughly 3700 fps with a number of powders including H322, BL-C2, H335, Win 748, Ramshot TAC, Accurate 2520.
I'd probably start with H322 because of its known excellent accuracy. Peak velocity is predicted with Win 748.
Keep in mind, this is only a prediction, but usually my QL sims come within 30 fps or so.
Same specs, loaded away from the lands, the projection is:
Load Density | Grains | FPS | psi |
Winchester 748:
99.1 38.2 3753 63000 Near Maximum !
Accurate No.2520:
101.0 38.6 3724 63000 Near Maximum !
Hodgdon BL-C2:
99.8 38.9 3720 63000 Near Maximum !
Hodgdon H335:
96.3 37.5 3708 63000 Near Maximum !
WARNING: This is only a computer projection. With all these powders I would start at 32.0 grains and work up. This also assumes an H20 capacity of 41.0 grains. You should measure the ACTUAL capacity of your fired cases. If it is less than 41.0 grains, that will dramatically increase pressure. For example, with 40.0gr H20 capacity, the pressure of 38.6gr of AA 2520 is 67341 psi,with bullet seated OUT of lands). That is high enough to damage brass and be dangerous.
Likewise, if your bullet is seated further down the neck that will increase pressure dramatically. When dealing with any new load, be conservative.