I recently offered to help a friend work up loads for a couple rifles (no good deed goes unpunished). The one in question is an older 721 Remington that started life as a .300 H&H but was rechambered by the original owner to .300 Weatherby (I've not loaded for many Weatherbys, only a .257 and .270). As I'm doing this on the cuff I'd like to use components I have in stock.
While I know there are better powders and perhaps bullets (accuracy will ultimately dictate the bullet). I'd like to use IMR4350 or IMR4831 as I have a bunch of both. I intend to start with the Hornady 190 Interlock BTSP as it is what my .300 Win likes and I'm well supplied with those also.
I'm sure IMR7828, RL22or25 H1000 or the like would be better but with the exception of the RL22 I'd have to buy more powder and the RL22 I have is all in one lot I'd like to save for my .300 Win as it's load is all developed and I don't want to change anything in it ever, it's a dandy!
A lot of my older manuals mentention 4350 and 4831 and while they are out of style some of the old stand-by's are still real effective.
If I could get 3,000fps muzzle velocity and reasonable accuracy I'd be tickled pink. As I've become a dyed-in-the-wool sub .22 caliber wildcatter over the last 8 or 9 years the less load development the better, I've gotten puny in my old age. Sure appreciate any help if you load or have loaded these powders for this critter.

The powder I use in my 300 Win Mag is IMR4350. My rifle doesn't like any other powder.

As far as the WBY goes I don't know if IMR4350
would work or not. I would guess you have to try it out.

I use H4831 not IMR4831.

I have a 300 Wby in a Weatherby Vanguard.

Don't know the difference in these powders.

168gr TSX - 82.5gr of H4831SC(short cut)

I started at 78 grs and tried up to 84 grs.
I got it out of the Barnes Reloading Book as I remember.

Hey Doug how you doing?

My Grandads old 300 Wby I had at the range the other day when you were there likes H4831 and 180 Horn flat bases.

I believe the charge is 80 grains and it goes in the mid 29's.

Not a rocket load I know but it has always done fine for me out of his old rifle.

Make it your best day!

Mark D

Here's the IMR website.

http://www.imrpowder.com/data/rifle/300weathby.php

They've recently lightened up the loads for the 300 wby probably because guns without freebore and those using rem brass instead of weatherby can add alot of pressure real fast.
Sierras latest data for 200 grainers says that 75.8 of I4350 is max and 75.1 of I4831 is max.
If I had to guess I'd say that rem probably doesn't have freebore.
I would say start at the data listed in the IMR site and most likely you will be able to move up towards the sierra data.
I have a couple of 300 wby and love the caliber. I just did loading for a friend with 2 custom weatherbies. One had freebore and the other didn't. I had to load the one without freebore at least 3 grains lighter or I saw big time pressure signs. Also using rem brass instead of weatherby which has more case capacity can make you reduce your loads another 1-2 grains.
As you can see there are alot of variables which add to the fun of "helping our friends"!

Yes.

If you look at the original Weatherby loads, IMR 4350 was one of the recommended powders for which they gave loading data.

All the loading manuals I have on hand, other than the ones by powder manufacturers, give loads for IMR 4350 and IMR or H 4831 powder for the .300 Weatherby. (H4831 is a bit slower burning, so a max load with H4831 is likely to be too hot if the same amount of IMR 4831 is used.)

I've used both IMR4831 and H4831 in my 300 Weatherby -- a Remington 700 Limited Classic -- with excellent results; accuracy was actually slightly better than what I got with IMR 7828, but there was a sacrifice of 100 to 200 f.p.s. in top velocity. For any practical hunting situation, that sacrifice is top velocity will not be noticable.

I load IMR-4350 exclusively in my brother's MK-V 300Wby. I don't remember the charge exactly (at work), but it will put 180gr. Speer Grand Slams into ridiculously small groups. Velocity is approx. 3,000 fps.

Great info guys thanks.

I loaded my MKv300Wth up to 83gnIMR4831/180gn that was hot,loose pockets,I backed off to around 81gn. Old Hornady book suggested around 78.8gn?max from memory.