Printable View
My first time, I'm looking for any info on the 7wsm in 130 grain cast bullet, my ww was oven treaded to 22.7 BHN, I have H4350 and would like to reduce the load 38%, this will give me PSI 27741 and 2377 fps, I don't know how much you can reduce H4350 powder in a 7wsm, or dose anyone have any other info on cast bullet for the 7wsm.
Thanks :confused
Joseph
Welcome to the forum, Joseph.
I am assuming that you have already slugged your bore and are sizing your cast bullets .002" above your groove diameter. If not, you need to do that first. A lot of folks have had good luck with cast loads in magnum cases. Here's a general formula to help you figure out where you're at with it that works with any rifle cartridge:
Take the jacketed data for the bullet weight/powder you want to use and subtract the starting load from the max load. Then, take your answer and subtract it from the starting load. This gives you your cast starting load and works pretty well with rifle powders.
Minimum Jacketed Load - (Max Load - Min Load) = Cast Starting Load
(Data from Sierra for H4350EXT) 59.6 - (64.2 - 59.6) = 59.6 - 4.6 = 55.0
I would start at 55.0gr and work up in 1gr increments. Even with a hardened cast bullet like you are using, you may be running into stripping problems before you get very far along and have to go to a much harder alloy like lino.
Work up incrementally until you find the "sweet spot": the groups will begin to shrink, then they will open up again. Play with minor changes in the charge weight slightly above and below your best groups to see if you get any improvement. For loads using pistol powders and specifics on the cartridge with cast, "search" next door at CB.
The potential problems with big cases are the low loading density and resulting possible position sensitivity of the powder in the case. This is usually overcome by using a mag primer and pointing the muzzle of the loaded rifle up before you fire to get all of the powder into the bottom of the case.