I wish mine would weigh 5lbs. Mine feels like I have a Rino hanging from my neck and I don’t mean Romney.
You're right - even a basic M4 clone weighs more than 5 pounds, empty. You can get under 5 pounds on a reasonable budget, but it requires a little focus. Years ago, I put a carbine together that came in at 4.75 pounds: Colt 'pencil' barrel w/ adjustable gas block, Anderson 'sporter' upper receiver, vented aluminum float tube, light-weight bolt carrier, and Cav Arms lower. It actually felt like a toy when you picked it up! I think the light weight was why so many GIs loved the M1 carbine, but most of today's ARs are definitely on the "obese" end of the weight range...