So I've got some questions for those of you who got well functioning 545 kits back in 2014, since it looks like a few were faulty.
what was the felt recoil like on them? was it noticeably less then 556? was it worse? about the same?
Did the piston and bolt carrier group weigh less then the 556 ones?
have you ever shot an ak74 or a 545 ar-15? how did it compare?
Besides the chamber, bore and bolt face (maybe the heavy spring in the older rifles) the rifles are the same. Those differences aren't significant enough that you could tell by looking at or picking up the rifle. They don't shoot much different either.