Home Forums Reloading Big Game Rifles Cold weather powders for .338wm

Ive been reloading for about two years so I'm far from expert level. Early last year I had some loads worked up with imr 4350 for my .338. The tightest groups I had were 3.5" @ 100y. An old timer that I usually avoid because he doesnt stop talking recommended I start using H4831sc because it isnt a temperamental.
I came back to the range a few weeks later and and shot the same groups but they were 3" lower. It was 25 degrees colder. I bought some h4831sc and really like it. With sierra 250gr bullets I shot sub moa once I figured out how many grain of powder she liked. Then in the spring the tempature jumped up to 55 degrees. Im still shooting sub moa but the groups were 2.5" higher. I load 55gr vmax with varget in .223 and dont have this problem. I predator hunt year round in temps from -30 to 70.
Do any of you guys deal with this in big bore rifles. The temp range I hunt a .338wm in are usually between 0 and 65 degrees. The shots I take are usually around 150y but some caribou shots are as far as 600y. A 2.5" variance @ 100y translates to 15" @ 600y. Any suggestions on a less temperature influenced powder?

H4350. IMR4451 should also be ideal, but I have yet to try it and have been pleased with H4350 (and I have a decent supply of it).

If you already have VARGET on hand, use that.
H 4831 will go bang, but it is really a little slow for best performance. Don't fall into the trap of separating powders for bullet weight either, VARGET will still get decent velocities with 250 grainers. Work you way up slowly to about 63 grains where I have chronographed an even 2700fps.

I've used IMR 4350 in my 338 for 42 years and have hunted in some extremely cold weather and never had a problem.

IMR 4350 has been temp sensitive in a number of rifles--7mm08, 284, 308,, 270, etc--that friends and I have tested. Hodgdon Extreme series has been very temp resistant--especially H4350 and H4831.

H4350 all day long for the 338 win mag..

I don't know why anyone would look any further than H4350, but to each his own

Lawrence,

Have a bud started loading for his 338. I told him grab some H4350, he shows up at the house. I show him step by step how to set up dies to minimize run out etc. I ask where the h4350 was at, he goes I didn’t grab any the store owner told me to use H4831. I was like wtf, so went and grabbed some of mine. We loaded him some ammo up with h4350. He goes you want this H4831 I was like nope the gun shop owner didn’t even sell you SC stuff lol.

IMO, unless your shooting “light” bullets....powders in the 4350 “burn rate” range are a bit fast. It works fine, but, I think there are better choices. Again, JMO, I prefer a slower powder, somewhere in the RL 22 or 4831 range! But.....that’s just me. memtb

I went through this same scenario about 20+ years ago and if old threads here are still available, try to locate it. Used the moniker of "Bobski" then. I developed all my loads in warm weather here in California and I was elk hunting mostly in late season hunts in Montana and Wyoming. My most accurate loads were with RL22 and 225 Nosler Partitions in 338 WM. Carried my chronograph to a hunt in Montana north of Yellowstone and chronographed at 12 degrees. Lost 300 fps or so but was lucky enough shots on that hunt were relatively short range and had no problems. At that time Vihtavouri had just come out with their 5 series powders which were supposed to be temp tolerant, and they were. I used N560 and found it to be quite stable. Tried N160 and it too maintained most of its velocity in cold. I believe i used N160 in a 338 Jamison and hit at 380 yards, one shot. I stopped hunting elk after the one in my avatar so I have done nothing more with the newer supposedly stable powders which also claim temp tolerance. Just went through some old data and saw where I also used H4831 in cold weather but did not read further about temp tolerance and don't recall experiences with it. I used nothing but 225 bullets, Nosler varieties. Also hunted with a 338 Jamison but recall nothing about the powders, but very likely the same ones as the 338 WM.

Fu ck dude. Sounds like my friend Troy. I think he did the same thing to me, but i told him dont worry about it, we can use it in your 270. No big deal. I also agree with you on the sc powder. You have 1 sitting next to the other and you pick regular ol h4831? The store owner could probably see your buddy coming from a mile away.

I know the shop owner he's a good dude. But yes he saw my bud coming a mile away..