I'd be of a mind to start out cheap and work my way up. Try the bulk Remington. They go 45 grain up to 62 grains, and the cheapest I've seen them recently is about $16.10 per hundred.
For a powder, I use H4895. It's not everyone's favorite, but one thing I found was that it had extremely consistent velocity from round to round. If a 5%-off-MAX load of H4895 doesn't get you some kind of a group, I'd go back and start looking at the rifle itself.