Funny thing you ask, since I also wanted to know so my friends and I made a 300 caliber competition... read on.
I had the pleasure of shooting a Tikka T3 in both 300 WSM (friend 1) and 300 Win Mag (friend 2). To me, I saw no difference shooting both.
Both guys when shooting each other's rifle agree that the difference (in recoil) is probably more psychological than real. The power is the same.
On the target, similar results are obtained, and both guys are great shooters. In fact, the T3 is very accurate with Norma brand cartridges and you could not see the difference both calibers. (~1 MOA = 2 inch grouping at 200 yards)
We even tried a small competition:
Hit a 1 inch thick metal gong @ 300 meters (used for black powder shooting; we use it to try to penetrate it from a far :
If you look closer:
Penetration is nearly the same, and they are very close together (yet it is 2 different shooters with 2 different calibers). We don't try groupings on it, since the range master would be p!ssed.
For laughs, look at the very bottom of the gong, you will see that my .270 did nothing at all to the gong.
So in the end, we all agree that it comes down to price per cartridge, and psychological recoil (after all, both were hurting after a box of ammo). See this link : Caliber Economics
Anthony (friend 1, 300 WSM) pays ~ 1.75 $cdn per quality cartridge while Jeff (friend 2, 300 WIN MAG) pays ~ 1.25 $cdn per quality cartridge.
You can be sure that when I get my Comfortech R1 (June/July), it will be 300 WIN MAG and we'll also redo the competition... this time with a semi-auto in it... We'll see how the Benelli R1 fares...
Hope this helps,
Chronos.
EDIT: The real question is, what bullet on the 300 WSM / 300 WIN MAG will pierce the gong at the same distance... armor piercing ?
[ 01-07-2006, 10:53 AM: Message edited by: Chronos ]