Screech,
Just so you understand , I have a 243AI and before that it was a std 243 and I love them both . I think it is a great cartridge and it is hard to beat for many shooting applications . Even though I have rebarreled to the 243 AI and am using a twist rate that is sufficient for the 107 smks , I stilll won't use it past 600 and that is with a double lung shot . Just my choices and I'm not saying that it couldn't go a smidge further.
Jim