I was going to build a 6mm AI a few years back but my gunsmith talked me into a .243 AI instead as the performance is almost the same and brass is very easy to come by for the .243 Win. I am grateful that I listened to him as it's a real shooter. Reduced loads for our local ground squirrels, full power for rock chucks and "outchonder" prairie dogs.
For sure a good way to go, but he asked about a 6mm AI in a long action. No way I'd do a .243 in a LA, and since he specifically asked about a 6mm AI, I didn't bother mentioning 6mm-06.
