I guess that I'm a little more direct than maybe I ought to be so don't consider this as being mean, just straight forward.
IMR-4350 is too fast for your cartridge and bullet combination. JUST C has pointed out the more appropriate burning rate powders for the 300 RUM. I would add that you can also try:
V V N-170
MagPro (I haven't tried this yet)
"MAGPRO A slow burning, double base, ball-type rifle powder developed specifically for all the new Short
Magnum calibers of both Winchester (WSM) and Remington (SAUM) except for .300 SAUM. This powder
excels in the 7mm WSM as well as the .270 WSM and even derivatives of the wildcat 6.5 Short Action.
Excellent in all overbore magnums such as the ULTRA magnums from Remington i.e. 7mm RUM, .338
RUM as well as the high performance .338 Lapua Magnum. Excellent flow in progressive auto-loaders
and volumetric dispensing equipment. This is THE magnum rifle powder to have."
You can do a search here and get some other suggestions from previous posters for surplus powders that will work, as well.
Does anyone know what the initial Break In procedure is on a new gun ? I have heard of cleaning the barrel after each round fired for the first ten rounds, then after every 3 rounds fired and so on. Also heard to use light loads and smaller bullets and such but havent seen a procedure. Any Ideas ?
Darn! Another trip to the gun store I guess. [img]images/icons/wink.gif[/img]
I have a bunch of 4350 on hand, that I use in my 270 win., and have also used it in my 22-250 as well. Hoping to use one powder all the way around. Yeah, they are definety different birds though- -the 270 load takes about 52 grains, the 300 can hold over 100 gr!
The bad thing about the RUM is that a pound of powder only loads about 75 rounds. I probably need to consider an 8 lbs cannister to avoid the hassles with lot variations.
Handloader Mag just published an article on the 300, and their suggestion was 92 gr of RL-25, or 91.5 of H-1000, for roughly 3000 fps with the 200 gr sierra. These loads were shot at 29 degrees F. though. How are these powders affected by temperature?