The .300 Win mag is fine if you can shoot it accurately. I used to use a .300 Wby as one of my rifles for deer hunting, but had it rebarreled this year to .300 Win Mag and am looking forward to using it. The rifle itself (stock design, weight,etc.)can have as much to do with recoil as the cartridge. A friend's lightweight .30-06 model 70 was the most painful rifle I've every fired, a lot more unpleasant to shoot than the .300 Wby.

On the other hand, I think you'd be well served to get something like a .270 Win or maybe a 7mm-08. These are plenty good for deer.