Under 6 pounds and can make the summer subruban sniper's day. Crosman makes the basis for some nice little carbines.
(left to right)
.177 2300s HiPac PCP conversion, all set up as you see it (scope, mount, LDC, etc), comes in at 4 pounds 1.8oz.
.177 Crosman 1700 comes in at 4 pounds 8 ounces as you see it. If you want speed (and can live with the lower shot count that comes with it) will need to enlarge the transfer port.
.5mm Crosman 2250 tanker. Co2 in the summer, 13ci HPA in the winter. Co2 is heavier, so it comes in just under 6 pounds (5 pounds 15.8oz.). Remove the on/off and use a 13ci HPA tank, and the weight drops to 5 pounds 9.3oz.). There is 12 of 5mm barrel inside that longish shroud.
.22 Marauder Pistol comes in at 5 opounds 1.9oz.