Re: .22-250 AI, .22-6mm or .243
I believe "fiftydriver" has sme good advice. I believe accuracy, KE and bullet performance go hand in hand. I have a friend that builds and swears by the 220 Swift. As you would expect he is a he is a "Dogger". He puffs these critters out to 500yds, but not even he would shoot a deer or larger size animal with his Swift. In his and my opinion, not enough KE left at the end of the ride to provide repeatable results. He built me a 6mm 284 last year and I like it. All of the ballisics I have to date are someone elses printed tables. As far as I'm concerned you can use those Black Box ballistic table for an estimate but when it comes down to getting the bullet to the mark you can toss that trash out the window. It takes hours of shooting to get your results and every rifle has its own fingerprint, so to speak. I have a custom 7mm Rem Mag and my buddy has a Semi custom 700 BDL. His rifle likes 145 gr Speer BT and mine likes the 140gr Barnes X BT. His rifle will put 3 in a little < 1" @ 100 yds. Mine is near 0.5" coupled with a Shephard scope. I didn't mean to go this long, but I would'nt be afraid to take a 500 yd poke(at a deer) with my 6mm 284 using at least a 105 gr bullet, I prefer Barnes X bullets. I have been successful at 500 yds+ with the 7mm. I have only taken one shot at this distance 562 yds, he drooped in his tracks
Good luck and first and foremost, strive for clean kills.