Re: Reloading the 300 weatherby magnum
The .300 Weatherby is my favorite rifle cartridge. I think you'll enjoy it. If I had to pick my favorite load it would probably be the following:
Powder: IMR 7828 (84 grains)
Primer: Federal 215M
Bullet: 180 grain Swift Scirocco
I have also had luck with other powders such as Reloder 22, H1000 and H4831. However, IMR 7828 seems to work the best in my rifle. I hope to try some Norma MRP and Ramshot Magnum soon. I am especially interested in the Norma powder.
I have tried various bullets and have had good results with just about all of them. As far as accuracy is concerned, I've had my best results with the Swift Scirocco, Hornady SST and Nosler Ballistic Tip (both 165 and 180 grains). I've also had surprisingly good accuracy with the Speer Grand Slam and Hornady Spire Point. The Nosler Partition, while an excellent game bullet, has not been so accurate for me in this cartridge. I prefer the Swift Scirocco to anything else because it's accurate, has a high ballistic coefficient and is stoutly constructed.
Since Weatherby rifles are freebored, I don't think varying the seating depth of bullets will have very much of an impact on accuracy. It hasn't for me at least. However, I have found that concentricity does seem to matter. I use a Lee Collet neck die to make very straight ammo that is remarkably accurate.
Good luck with the .300 Weatherby. You'll like it.