aloha rook
i have a SIG 556
and don't own any ARs
the SIG is HEAVY
and aftermarket parts are limited, since it is a proprietary system
although there have been significant improvements in the past year, and more to come
but it is nothing even close to the AR platform when it comes to mods
fun to shoot from the bench, supposed to be reliable (think of it as a modernized AK)
easy to clean/maintain
a little tough on brass (ding on ejection, people put a piece of fuzzy velcro to reduce impact)
ejects at 1:30-2:00, so safe for leftys to shoot
if i am ever at the range and you are there, you are welcome to try it out
I got the sig 556.
And it's easily my best AR.