I’ve got a few 223/5.56 and one 300blk. Had a 450 bushmaster and traded it off in 2013 due to ammo shortage issues and I just wanted everything to share as many parts as possible for a particular frame size. The AR10/308 size rifles are definitely worth it. I spread out buying parts and building my Aero M5 for over 2.5 years, just buying parts when I had extra cash and saving until sales. If I do another larger frame I’ll probably go the same route.