Yeah, if you are unfamiliar with any of your loading components or a mix thereof, I would start with one loaded round @ say 15% lower and see what the velocity might be. Too, check the primer for any issues. Then work you way forward.

Remember it backs out of the case somewhat due to pressure on ignition then the case under pressure is forced back against the standing breech and the primer is pressed back in place.

Hochachtungsvoll,

Raimey
rse