i know this is a old post, but i just came across it and wanted to put my 2 cents in. as TOMCAT said they are nearly identical in 150-190 bullet weights. i may be wrong on this but i think for the .300 win mag the smallest factory load you can get is 165gr, where with the .300wsm you can get 150gr. if your hand loading you have more options with both. the .300wsm has several advantages over the .300 win mag. with all the wsm's .270,7mm,300,325 the ballistics are based on a 24" barrel give or take a 1/2" depending on the gun maker. where the .300 win mag is based on a 26" barrel. also the wsm family are short action's. with that and the short barrel you'll have a lighter gun and a little easier handling gun. having shot both of these guns i will say the wsm kicks a little less with the same bullet weight,due to the wsm having less powder. if white tail's is what your mainly after, i recommend the .270 wsm. it's the only gun i've hunted with for the past 12yrs. it is a AMAZING round. with the right ammo it is capable for anything from prairie dogs to elk. also the .270wsm is the only round in the wsm family that improved on the regular round. were the 7mm,.300 all duplicated the performance of the regular round, the .270wsm exceeded the .270 win. it matched and in some bullet weights passed the .270 weatherby mag, again with a 2" shorter barrel and a short action. now that 2" and short action doesn't sound like much, but if you hunt anywhere where there's hills or mountain's you will appreciate the lighter gun. someone said they were looking at a tikka. the tikka t3 in a .270,7mm,or .300 wsm comes with a 24.3" barrel, not a 26". also before anyone chimes in and says the .270wsm is to small for elk, has NO CLUE on what they are talking about. i have personally taken 6 bull elks the largest being a very mature 6x6, taken at 287yds with my .270wsm. also which ever gun you decide on, i would NOT recommend using BALLISTIC SILVER TIPS for anything bigger then a squirrel. they just don't hold up at all. core-lokts or better yet barns tsx or ttsx DEVASTATING rounds. federal now has their own line of all copper bullets, should be as good as the barns. good luck & happy huntin.