300yard rifle matches?

[wally]

The guys who showed me the ropes getting into 600/1000yrd benchrest and F-class said the basic rule of thumb for self-qualification: When you're reliably delivering 1" at 300yrds, then you're ready for 600/1000yrd competition.

Bench rest maybe. But if you are reliably shooting 1" groups at 300 yards you'd be regularly winning F class matches as the X-ring is ~1/2 moa (1.42" at 300 yards or 5" at 1000 yards).
http://compete.nra.org/documents/pdf/compete/RuleBooks/HPR/hpr-book.pdf

Don't over think it. Take what you have to a match and enter whatever division your equipment is most appropriate for. Shoot, have fun, watch and learn, before spending a ton of money.