Nothing wrong with .300WM, but it’s overkill for most of the matches/competitions you’ll find and will get expensive fast if you shoot it a lot. But rock it if it works for you!
As for competitions, AZLRPRS hosts a monthly match out at CowTown that’s very much wirth checking out. I haven’t shot it in a few years for a variety of reasons, but as the weather cools down, I’ll be going every other month again. Check it out!