I have a Ruger 77 MKII in 300 WSM and it will shoot a .6" group at 100 yards with my 180gr handloads. My #1 7x57 mauser will shoot under 1" also. Ruger also comes with rings and the bases are machined as part of the action. I just ordered a Ruger 77 MK II in .223. I like Ruger for their accuracy, price and quality. I think Ruger has some very nice walnut stocks on their $500 off the shelf rifles.

As for caliber I would go with 30-06 it will do everything the .270 and 280 will cheaper with more bullet options and weights.