Tweaking my 7WSM load

ZLBubba

Sergeant
Full Member
Minuteman
Jan 15, 2009
843
33
42
Maryland
I've got a Gradous 7 WSM that's always been good to me, but now I want to tune my load for a little more velocity IF I can do it without sacrificing accuracy. That's always the trick, right?

Full disclaimer, I built the gun as a light tactical rig so the barrel is cut to 22" without the break. It shoots in the .2s and .3s for five shot groups, which is about as good as I can do. My velocity is right at 2800fps with the Berger 180gr Hybrids over 69.8gr Retumbo in Winchester brass. I'd like to get it up to 2900 to have just a bit more reach. I did a ladder test last week and found that in my gun, the max is really about 71.5gr Retumbo. Those cartridges showed both cratered primers and ejector swipes.

My question is, should I leave well enough alone or try a new powder? I've got some Magpro, but I saw that the VV N570 may be the ticket if the gun shoots well with a hotter load. The worst I could do is waste money on another lb of powder. Does anyone think I've got a good shot of finding a better recipe, or should I just stick with what I've got?
 
M

milo 2.0

Guest
I've got a Gradous 7 WSM that's always been good to me, but now I want to tune my load for a little more velocity IF I can do it without sacrificing accuracy. That's always the trick, right?

Full disclaimer, I built the gun as a light tactical rig so the barrel is cut to 22" without the break. It shoots in the .2s and .3s for five shot groups, which is about as good as I can do. My velocity is right at 2800fps with the Berger 180gr Hybrids over 69.8gr Retumbo in Winchester brass. I'd like to get it up to 2900 to have just a bit more reach. I did a ladder test last week and found that in my gun, the max is really about 71.5gr Retumbo. Those cartridges showed both cratered primers and ejector swipes.

My question is, should I leave well enough alone or try a new powder? I've got some Magpro, but I saw that the VV N570 may be the ticket if the gun shoots well with a hotter load. The worst I could do is waste money on another lb of powder. Does anyone think I've got a good shot of finding a better recipe, or should I just stick with what I've got?

Upfront, your barrel length is what's limiting you. I would almost guarantee more velocity with N570, but not 100fps.
And then you need to ask yourself if you're willing to pay $12.00 a pound more for that increase. It just is what it is.

In the Bolt section, a guy is thinking of building a 7mm SAUM with 16" tube, Holy shit!
 

ZLBubba

Sergeant
Full Member
Minuteman
Jan 15, 2009
843
33
42
Maryland
Yup, I hear what you're saying, Milo. In fact, once this barrel wears out I've got another med Palma on the way from Bartlein: 1:8.4" twist, fluted to finish at 26". I love the gun that I have, but I thought a little too far outside the box on this project. Nonetheless, Robert will spin up that new barrel for me at some point late this year and I'll correct myself. Still, I can make hits out to 1600 with the load I'm currently shooting out of the 22" tube. That ain't bad.
 
M

milo 2.0

Guest
I've seen a 7 saum, 22" go to a mile, it's there. If you'll take advice, go as long as possible, and still be able to store it in a Pelican 1750.
With or without the brake installed, your choice.