I picked up a used Win Mod 70 lefty last year for a very good price. It happened to be chambered in 270WSM. I hunt upstate NY and have no need for magnum power, so I developed two loads duplicating 270 Win ballistics. One load groups at 0.9" and the other 0.6".
I'll be using it as my primary deer gun this season. So far I'm pleased.

The case capacity of the 300 WSM is almost the same as the 7mag case.I have found,whatever load my 7mag likes with 140gr bullets,my 300 WSM likes the same load with 165gr bullets.So that's the way I kinda think about the 300 WSM in terms of where it falls in the pecking order,as 7mag necked up to a 30 caliber.

I have owned 2 WSM's , one in 7mm and the other in .270 . The 7mm I bought when looking for a .270 Win. or similar . Rifle was a model 70 featherweight demo and I got it at the right price . That rifle shot 140gn Nosler BT and AB at about MOA for 5 shots with H4831SC and Re22 at 3150 FPS . Would do under 3/4 MOA with the 160gn AB at 3030 FPS in front of Re25.
Being a bit of a Sako fan I sold the featherweight and bought a model 75 deluxe about 12 months ago . Couldn't get it to shoot much better than about 1.25 MOA with 140gn accubond or 130gn ballistic tip . Tried a heap of powders .
Rifle likes the 130gn Barnes TTSX and 130gn Berger hunting VLD and shoots well under MOA with either at 3250 FPS.
Both rifles have performed well in the field with some kills at over 400 yards so I have no complaints.
Never had a hint of a feeding problem with either rifle .
Good friend of mine was sufficiently impressed with the 7mm that he bought one for himself after a hunting trip that we did together .