Honestly Capt, I've taken a few Moose with .30-30's pushing 150 grain corelocts. Granted I was within 150 yards on every one of them, and within 75 yards of MOST of them. At 300 yards, I really would want a minimum of 180gr bullet weight. I usually carry one of my .30-06's loaded with 220gr Hornady Interlocks nowadays and that knocks the snot bubbles out of them real quick and proper. At 300 yards, the .308 is kind of a minimum cartridge. Especially for a Big Yukon Bull. I would personally recommend you get to 200 yards if at all possible even with a 180gr bonded bullet or solid. They really aren't hard to get close on in MOST places unless you are old with horrible knees like me.