I have a question about ar uppers. are they interchangable? meaning if i have a .223 upper, and i want to go with a .308 can i use the same lower and just get a .308 upper? or if i wanted to go with a .22 from a .223. thanks

You have to have a .308 lower, the magazine is larger. You can use your lower on the 22lr lower.

I believe with the AR15 lower you can interchange a 204, 223, 6.8 SPC and 450 upper. The 22 is simply a bolt and mag change out. the 308 needs an AR10 lower.

Thanks guys.