Re: 300. win mag experiences!!
A 180-gn bullet works best and is typically used in the 300wm. Haven't used anything else in that cartridge for years. 76gn RL22 works fine with the BOSS adjusted to the standard recommended setting for that setup.
It's a good all-round cartridge for our whitetails, black bear, etc, but a bit light at distance for larger animals. Best to have a good .338 like a 340Wby or 338LM using 250 gn Partitions for longer shots at big stuff. Would not go to a hotter cartridge than that though with a .308 or .338 bullet. Took my first moose with the 300wm but the bullet just broke the upper foreleg and lodged into a rib. Moose was not impressed, and ended up being a lot of work.
The 300wm has a sharp bite to it, so you should tame it down with some sort of brake and get it with a heavy barrel and stock. Mine has a really sweet disposition now and I can hit the gong all day long at 300 yards with 2 or 3-inch groups (with sufficient cooling periods of course).