I have done a couple AR 15 in 22 cal builds, and have had fun doing so and learned the platform pretty well for now. My question is are the lowers any different for a 30 cal versus a 22 cal, Obviously the barrel and upper bolt assembly and carrier would be, but thinking about building one, just because! Point me in the direction of what I need to know or let me know here if you have time to explain the difference between the two calibers thanks Eddie.