I may finally be building up a light rifle on a Hein action. This question just boils down to accuracy potential.
Is either of these rounds more accurate than the other?
I have owned numerous 300 Win mags and never felt disappointed but have never fired a 300 WSM yet.

I have shot both the 300WSM and the 300Win. IMO they are both very capable cartidges. Accuracy wise I didn't notice a difference (I am by no means a sharpshooter). I do know that the 300Win will handle the heavier bullets a little better than the 300WSM.

I just started shooting my 300WSM and like that is it a short action which does make the gun shorter and lighter.

I would never be shooting bullets less than 165's or heavier than 180's

I'd ask Hein what they would recommend. I am a fan of the WSM's, and in mine, with equal barrel lengths, they develop about the same velocities. I have had feeding issues with a couple of my .270 WSM's...never any of my four 300 WSM's though--that said to illustrate that there are indeed feeding problems from time to tiem with the short mags. If Hein says that is a non issue, than I would actually lean toward the short mag for the bullet ranges you listed especially-- I really ike NOT having the belt.

Some folks will tell you that the sharper shoulder on the WSM case will lend itself to inherently better accuracy, I will say that I got excellent accuracy more easily out of my 300 WSM's than my 300 win mags.

Good Shooting--Don

The Win Mag will handle heavier bullets. When loading the WSM even 180s seat down into the powder capacity.

Both are capable of being very accurate. It matters more on the quality of the rifle than the cart.

I've read about the design of the WSMs and the theoretical accuracy advantages. Mostly the advantage being a shorter powder column which allows for more consistant ignitions from shot to shot and makes good sense.

I own both and the Win Mag will definitely out shoot the other but, like I said, it has to do w/ the quality of the rifle not the cart it's loaded w/ under most circumstances.

I will say that the 300WSM is quite efficient, I get the same velocity as the Win Mag w/ around 10 grains less powder and a 2" shorter barrel. The Win mag will shoot faster but, when comparing the same speeds the SM is more efficient.

Another thing you may want to consider is that the short fat carts have trouble functioning in some actions.

Good Luck

Reloader