Originally Posted by Shortmagman
I own 4 short mags, 2 of them are 300 WSM's . With my 300 WSM's I have found that I get my best results using N550 powder and 165-168 bullets.Using two grains less than the max load listed in the Nosler #6 Manual I can get around 3000 ft/sec out of both guns. I have a Ruger Mark II with a 22 inch barrel and it will shot these bullets at 3000 ft/sec. or better. I bought this gun as my elk gun to be carried in the mts. It is short and light for the power that it produces. I have shot only one factory load in this gun. Federal 180 Nosler solid base bullets and it shot these bullets at 3017 ft/sec. My Winchester Model 70 with a 24 inch barrel shot the same load at 3055 ft/sec.. RL-19 will also work well in the 300 WSM's.
I have yet to see a 30-06 that would come close to 3000 ft/sec with a 180 grain bullet.
I also shot a Winchester Model 70 in 270 WSM. My favorite load for this gun is 140 grain Accubonds and RL-22 powder. I get 3100 ft/sec with this load. I also have a good load using 140 Barnes TSX's and RL-22. This load will achieve over 3100 also.
Good info but I would like to point out a couple things. N550 achieves 3000 fps with 165's in your gun. I can get that same bullet to 3000 fps with IMR4007ssc and it is much easier on the barrel. But either way, 30-06 can do pretty much the same thing with this bullet. If factory 180's in the WSM go over 3000, why is it we can't get much over 3000 with 165's from handloads? I'll tell you why. Ball powders. Factory ammo is loaded with ball powder and it is dense enough to pack a lot more in than a stick powder and it gives more velocity as a result. Only problem is that for handloading, I don't want to use ball powders. So that puts the expansion ratio of the 300 WSM with 165's or 180's right in the crapper for non-triple based stick powders if you want speed.
Secondly, you are loading ammo for Win model 70's. That is just about the longest box magazine out there for a factory gun. This allows you to move the bullet out of the case a bit and gain some case capacity back. Win's reamer for the WSM's can be longer in the throat because of the magazine. It is really the way all the other companies should have done their WSM's. But Remington, Ruger, and Browning guns basically reduce your capacity to 63 grains max with a big stick powder like RL19 and I have yet to see that give velocities of factory ammo.