No reason why a .300 WM can't be a thumper, particularly if you are a reloader.
Here is a blurb from the description of the "SIERRA - BULLET - 30 (.308) 220 GR RN PROHUNTER," sounds like they think this is a short range thumper, in the .300 WM, choose your speed;
In rifle cartridges, these bullets are highly recommended when good expansion and deep penetration in medium and heavy game are required at short to medium ranges. These bullets give pinpoint accuracy because of their short lengths for their weights. This short length for a given weight allows a rifle barrel to stabilize a considerably heavier roundnose bullet than would be possible with a Spitzer-pointed bullet of the same weight, which would be considerably longer. If the shots are fast and at short ranges or the game is big and dangerous, these are the bullets to choose. The 220 grain #2180 is the real heavyweight and is suitable for the largest North American game and many African species.
I bought a couple hundred of these 220 RN's to try out in my 7.62X57 rifles for spring bear season.