William, Hey, long time--NO LBT stuff for you!
I have a link below from GG&G's site. They supply two rails with the mount, one for the M3 and a 1913 rail. Although it's not designed for a handguard, it will work. Or if you had a solid FF tube, these would work there also. A cheap way of adding a rail to a handguard or a rifle stock for a bipod, etc.