I would recommend a 25-06. They will do the job at 400 yards. The recoil is not bad especially at the 100 gr bullet weight. You can try 110,115,117 and 120gr as well. The ammo availability is not as mainstream as 243,270,30-06 and 308 however order online if necessary. You can pickup a Marln XL7/Nikon Prostaff 3x9 with DNZ 1 pc mount/rings for around a total cost of $500 and make a tack driving long range shooter.