7mm mag

Well I have another young fellow interested in reloading he shoots a Browning X-bolt and has decided to go with 160gr. Partitions :wink:.
I haven’t loaded partitions for the 7mm mag in over 25 years, just a favour does anyone shoot them with IMR4350?
I know the load will be around 60.0grs but does anyone have the sweet spot for the OAL? It shouldn’t be hard to find but I guess I am being lazy :lol:.

Blessings,
Dan

Dan,

I never used 4350 in my 7RM as I focused on other powders. Consequently, for years, I ran 175 grain PTs and TBBCs, almost always charged with H870. (Yeah, I still have a few pounds squirrelled away.) I did, however, work up one load with 160 PTs.

PMC WLRM 2.806 NOS 160 PT H100V 59.5 2983 +/- 1 0.59

This load gave me half inch groups at 100 yards.

If it were mine I’d start .020” off the lands or max mag length.

Like Mike, I’ve never used much 4350 in the 7 mags but Bill does and reports good accuracy with it. He might even be using it in his Mashburn this year?

Dan
I will be home today and look at my load data, I have had great luck with the 160 and H -4350. I believe i am using 62, And for load development I always start at maximum magazine length, then work back.

Dan I am using 61 gr, of H-4350 with consistent sub MOA, 160 AB

IMR-4350 works best with 150gr or less,but I think the slower powders like Reloader-22 and Reloader-26 will work better.I have used as much as 65.0grs of IMR-4350,but that is a bit over max.63.0gr is about as high as I'll go.

Dan I used H1000 69.5grs under a 160gr AB OAL 3.290"/ 2.704" off Ogive OAL.
It runs around 2950fps out of my 26" barrel.
It's lightly compressed and I use a 4" drop tube to settle the powder in the case.

With a 160gr AccuBond,66.0grs of Reloader-22 gives me 3000-3100fps depending on which of my four 7mags I'm shooting it out of.All four of my rifles shoot this load really well.I haven't tried it yet,but I think 68.0grs of Reloader-26 will do the same or better.It's on my list to try.

Back when I was hunting with a 7RM, I got my best accuracy/velocity with a near max load of H4831, but that was many, many moons ago......

I do as Scotty said . I start at either max magazine length , or so much off the lands , whichever is shorter . by starting from here you only have one way to go , that is shorter .

Back when nothing slower was readily available, I used 4350 with 160 grain bullets in my 7mm mag., but it is a little quick to be ideal. When IMR 7828 came along, I switched to it and in recent years I have gone to RL 22. The favorite bullet in the 7mm for my friends and me is the 160 grain AccuBond which has always performed great on deer, elk, and moose, lots of moose. It performs as well as the 160 grain Partition, and flies a little flatter.

Don't be afraid of IMR 4831 with 160 bullet in 7 RM ... it ll shoot great. Start a couple grs below and work up. Not a speed demon but you ll get 2900 or so. Everyone is into the extreme powders but I've had great luck with IMR4831 over the last 30 years in 270, 7RM and 300 WM.

R22 is another great one with 160 s... also not an extreme powder but if a 7 RM won't shoot little groups with 65 grs of R22 then try a different bullet. Probably another 25-50 fps over IMR 4831 in my experience.

Good Luck.

Back in the old days,the 7mag was factory loaded much hotter than today.It's only loaded around 58,000psi,which is about where a lot of non-magnum rounds are loaded.Most all my loads usually run a couple of grains over the book loads that run around 58,000psi.I see no reason a 7mag cannot be run safely at 60,000-63,000psi.If I wanted my 7mag to be loaded down like a 280,I would have bought a 280.Here is a page from a 1967 Lyman Manual.

sorry Dan , my reading comprehension skills suffered . I gave you AccuBond info . I'll get it removed from my post above .

I agree with Scotty again . .020 jump should get you a great place to start with the Partition , if you can load that long in the magazine . maybe show your young reloader to load 5 rounds with a .015 jump , 5 with a .020 jump , and 5 with a .025 jump . shoot these with a minimum powder charge and see what shoots best . now you have 15 fired cases to use for powder work up . I'm assuming this is virgin brass .

When I loaded for a friend's 7mm with 160 AccuBond I set the col at max mag box with reliable feeding. Ran RL22 and i would have had to try to make an inaccurate load with that combo. Never seen a rifle that had that many accuracy nodes while working up to max charge.