Have you looked at the M4 profile 16" barrel?
I replaced the AK upper (14" heavy barrel, AK brake) with the 16" M4 upper.
Most barrel and upper weights are not posted, but if you call Bushmaster, they will tell you the weights.
I am pretty sure that I shaved 1 pound by going to the M4 profile.
And I got higher velocity too!
The AK upper was too loud, and the heavy barrel seemed to take forever to cool off after 100-150 rounds.
The M4 upper is lighter, quieter, and cools off almost instantly.