They're both in the same ballpark, and 10 years ago when I decided to get a 300 magnum I couldn't decide which one to go with. Finally decided to go either way depending on what the rifle was, its price, etc. Almost bought a 300 Win Mag Ruger but someone else beat me to it. Wound up with a new Savage Model 10, (pre-accutrigger) package rifle in 300 WSM, and I love it, (after putting on a Leupold 3.5-10x in Leupold rings and a Rifle Basix trigger). I find the 300 WSM to be accurate and easy to load for and my 300 WSM handloads all seem to have very low extreme spreads (very consistent velocity). Never, ever had a feeding problem in my Savage. My pet load launches a 150 gr. Accubond at an average 3207 fps with only a 9.35 fps extreme spread. Biggest game this rifle ever took with that load was a 4x4 mule deer in 2006 (192 lasered yds., one shot, DRT). Someday if I ever had the opportunity of an elk hunt I'd be working up an elk load for it probably with 180 gr. partitions which it seems to like.
