I would try a shoulder pad and a good muzzle break. There are a lot of pet loads out there for the various 6mm bullets, but they will probably run just as much if not more than your .300 win mag. You could always go with the ever workable 30-06. If you believe Jeff Cooper, thats the only caliber you would ever need.
Alternatively, shoot something like the 458 Lott for awhile; after that a 300 Win. Mag. won't seem so bad.
For shots out to 400 yards on deer, common cartridges that will work well, have a flat trajectory and less recoil than a 300 Win. Mag. include 25/06, 270 Winchester, 280 Remington and 7mm Remington Magnum. If the recoil still bothers you, you might consider a muzzle brake.
As for a lighter/shorter rifle; I love my Encores including the unbraked 300 Win. Mag.
If you are worried about recoil, the weight of that rifle is actually a good thing. I have a Browning Stainless Stalker in 300WM, and love it. It is shooting 180gn Sierra Gamekings at 3000fps, very well, and is zeroed for 300yds. It has a muzzle break from Stillwater Precision, but Steve Baldwin does a beautiful MB for $150. It will tame that thing right down. As for loads, try loading down to a 165 grn or 180 gn Accubond. If you look at the ballistics tables in the back of the reloading books, you will see that the 180gn will do you a better job waaaay out there than the lighter bullets that shed their energy quicker.
338-06 might be a player. 30-06 ballistics with heavy bullets. Near .338 win mag performance with much less recoil. I have one in a Savage 110 that is a sweet shooter. There is factory ammo, but you really ought to reload if you do one of these. I do like the 25-06 too, but the Weatherby 257 mag would be a better choice. I also have a 7mm-08 which is nice. The.280 Remington may be the best of the lot. I have friends who use these very effectively. CB
HA! This thread is a joke right? If you think .300WM is bad God forbid you ever shoot or lay your eyes on the .30-378 wby. mag.
First look at the weight of your rifle? I had a 7lbs rifle that I had to put a brake on to tone it down (and before the nay sayers join in myself or others around haven't noticed much of a noise increase). Kicked pretty good. You have all types of options in the 300WM caliber
Add a limbsaver recoil pad. It made a significant difference with my 300 RUM. If you find the 300 is still too much then you may consider a 270 or the venerable '06.