Right now I'm only shooting at 200yds buy I want to stretch it out to 400yds. I'm looking into 3 different guns. Savage 110 tactical in either a .308 or .223 or CZ 527 varmint in .223. I'm leaning towards the .308 savage but if a get a .223 I can share ammo with my current SIG 556. I have a spare Nikon Buckmaster 6-18x40 for whichever I go with but what would your recommendations be. Either gun will be bought used to keep costs down.