The Lee 22-250 seater die will work with the AI case....some other brands won't due to the tolerances at the body. As you already know, the collett die works and works very well.

However, you'll eventually need to bump the shoulders back on your fired cases. I would buy the 22-250 AI die set and go from there. Set the sizing die up to only bump the shoulders back enough to allow easy chambering (prolly around .001-.002"). Sure, you'll have to use lube but you may find that the FL sizer works just fine for you.

If not, spend the $18 and get the collett die! ;D