I recently picked up a Colt Sporter A-15 ... which is very close to the M-16A1s we used in the Army I was in ... I almost threw the Colt up in the air it was so light ...
Colt 5.56(10.3) MK18 workalike ... about 8 pounds in shown config
Custom 5.56(10.5) Mk18 work alike ... about 9 pounds in shown config (the thermal adds more weight)
BCM 5.54(14.5) M4 work alike ... about 10 pounds in shown config (DD rail is heavy)
Colt 5.56(18) weighs about 10 pounds in shown config (light profile barrel)
Custom 6.5(18) weight about 11 pounds in shown config
To the rear, .300WM weighs about 15 pounds empty and pushes 20 pounds in the field
To the front, .50BMG weighs about 25 pounds empty and pushes 30 pounds in the field
The .300WM and .50BMG would be fired primarily from tripods.
The DMRs 6.5(18) and 5.56(18) would be fired from tripods about about 150yds or standing unsupported closer in.
The Carbines would be fired mostly not from tripods, except when zeroing.
Yes, these are heavier than the rifle I had in the Army.
Then add in the helmet with pvs-14 and thermal and that's another 5 pounds ... then the pack ... another 5-10 pounds ... altogether I try to stay under 35 pounds for a field kit, in order to stay mobile.