RE: .243
With the right bullet it's capable of 300 yds easily, but is the man behind the gun ? 300 yds is a long,long way. I've made some 250 yds shots off a good rest. Dont think I would try farther than 300, with any caliber.
P.S. Have you ever tried to find the exact spot a deer was standing when shot from 2 or 300 yds away. I have this problem in one area I hunt here in texas, (brush country) This is the hardest part of recovery, finding the exact spot and sign of blood, and from 2 or 300 yds, its really, really tough. Ive spent hours looking for blood on deer shot from long range because you just cant pinpoint where exactly he was standing, but after finding blood my deer were found very quickly, only 20 to 50yds from there. I shoot a .243 myself and it's all I ever need. Works damn good too.