Thread: New powder time

Greetings @Sideshow,
Of the three powders you mention I would favour the N150 as it is the only one of the three powders that there seems to be factory data for the 7x57. That is just me though and you may prefer 550 or 555 for the extra velocity, In any case I would chronograph your 48 grain H4350 load with the 139 grain SST followed by a start load of your preferred powder. You could then work up chronographing along the way until you approach the speeds listed for the 7mm-08 and the projectile weight you are using. 7 x 57 data is a little scarce for the newer powders as the cartridge is less frequently chambered these days. I suspect that your 48 grain load is right up there with pressure as supported with the data you have from the reloading tool. Hodgons listed 46.5 grains as max with H4350 at 45,000 CUP. This is old data likely from the 1980's and the current (post 2000) H4350 is significantly faster so I would regard the velocity obtained with that load as absolute max. Please proceed with care.
Regards Grandpamac.