There a long list of powders that will work just fine with this bullet weight in 300 Winnie.
The ones I've actually used and can speak to for bullets around this weight range (180-225 grainers of various flavours) are h4831ssc, Imr 4955, imr 7977, imr 8133, imr 7828ssc, H1000, imr4350, rl22, rl25, superformance, and h50bmg (not joking haha). I hear good things about rl23 and rl26 and the newer LRT and StaBall HD as well. No experience with those.
H1000 is very hard to find fault with…it ain't gonna be the fastest muzzle velocity possible, almost certainly, but it's consistent as all get out, temp stable, and cooler burning. It's a safe bet. IF YOU CAN FIND IT.
H4831ssc is rarely a bad choice but it's not the best. It's a jack of many trades and a master of none. It is very predictable in its behaviour and this is a good thing, and temp stable. Probably won't get a
percent case fill. I prefer a full, even slightly compressed, case with any magnum but that's just me.
The 4350 burn rate will certainly work but i no longer use that burn rate in these kinds of cartridges with heavy bullets. Won't get the case fill i prefer, the es numbers suffer because of that, and you almost certainly could get significantly greater velocity with a slower burn rate.
This is not where superformance shines at all. Enough said. It's a progressive burn rate ball powder, if you're not able to get 100 percent case fill or very very close to that with this powder in a given cartridge with a given bullet weight save yourself the trouble and just don't. Keep moving.
Rl22 has the potential to realize the full capability of this cartridge at these weights. It's also temp sensitive. The most temp sensitive of this bunch in my experience. That doesn't mean I wouldn't recommend it, just don't go loading up a "light pressure signs" load in January and expect everything to be fine in June. It won't be. Ask me how i know.
H50bmg is right out!
. Entirely too slow.
The enduron powders, 4955, 7977, 8133, have been discontinued and that sucks. 7977 was a sweetie in this cartridge with heavies, as was 8133 with 220+ grain loads compressing the powder. 4955 is very abrupt to pressure spike…in both the 243 and .300 win mag I've had it happen that moving up one grain was the difference between ZERO pressure signs and a stiff bolt. I hate that. But it's a fine powder if you just want some moderately loaded ammo that's temp stable and copper erasing as well. Just don't chase velocity with that one if you do happen to have and use it.
This brings me to my favourites at this time, and they're both grossly underrated at this point and real sleepers as far as I'm concerned. Imr7828ssc and Rl25. They're right beside each other on a burn rate chart. In my experience rl25 is actually slower burning than they suggest but it's very dense and it's not hard to get a full case with either of these and obtain full power 300 win mag loads with fine accuracy and sd numbers with 200+ grain bullets. They're a bit temp
Sensitive…not as bad as rl22 or rl17 that's for sure! Perfectly acceptable to me and I live in a place that experiences tremendous seasonal change. They're also not nearly as INSANELY competed for, even on auctions and gun shows and such, as rl26, h1000, or retumbo. They'd be my first choices from what I actually have.
7828ssc
Rl25.
