RE: 300 yard accuracy?
Yes, thank you AA for a great post!
As he mentioned you really have to shoot it with the ammo you want to hunt to make sure it's doing what theory implies it should be.
One question AA, were you holding high for those shots or ? My handloads are 0 at 200 and 6.1" low at 300 (in theory, they actually drop a hair more I've noticed).
And to answer your question, if you can get under 5-6" groups at 300 yards with a hunting riflle that's good enough for deer and elk assuming you are consistant at that range and would only take a shot like that with a very solid rest. 300 yards (checked with a laser) is an amazingly long poke at an animal and should not be attempted unless you've shot paper at that range to be sure you are where you should be. I've shot 3 elk in the last 3 years that were all over 300 and I'm very thankful I had a rangefinder with me as I probably would have shot over if I was guessing the range as they looked much futher away (1st was 360yards, 2nd was 322y, and 3rd was 302y).