Got my bipod mounted yesterday and thought I'd share my method for those interested. My rifle is a DPMS 6.8SPC carbine, 16" barrel. Since the lower handguard has holes in it too large for the QD stud and too close together to permit drilling a new one, I had to do the following:
Used a 10-32 threaded QD stud.
Bought a Tee nut without prongs (aka hat nut/capture nut) in 10-32 X 9/32 at Lowes (comes in 2 per pkg for $4.00), filed two sides of the flange 180 degrees apart to the same inside measurement of the handguard recess;
Cut a rectangular 1/8" aluminum plate (old road sign) to span the distance of the first 3 holes in the handguard and to the same inside measurement as the Tee nut flange, then painted it. Gives you force displacement and also acts as a spacer at the underside;
Used a 1/4" nut, threads drilled out with a 1/4" bit to accomodate the Tee nut, as a bushing to insert in the second most forward hole in the handguard. The hex points on the nut may need to be filed a little bit. (you want a snug press fit).
Put everything together and screwed in QD stud (since the 1/4" nut sticks up about a 1/16" no washer is needed. The bipod keeps the stud from coming loose).
Used a 10-32 threaded QD stud.
Bought a Tee nut without prongs (aka hat nut/capture nut) in 10-32 X 9/32 at Lowes (comes in 2 per pkg for $4.00), filed two sides of the flange 180 degrees apart to the same inside measurement of the handguard recess;
Cut a rectangular 1/8" aluminum plate (old road sign) to span the distance of the first 3 holes in the handguard and to the same inside measurement as the Tee nut flange, then painted it. Gives you force displacement and also acts as a spacer at the underside;
Used a 1/4" nut, threads drilled out with a 1/4" bit to accomodate the Tee nut, as a bushing to insert in the second most forward hole in the handguard. The hex points on the nut may need to be filed a little bit. (you want a snug press fit).
Put everything together and screwed in QD stud (since the 1/4" nut sticks up about a 1/16" no washer is needed. The bipod keeps the stud from coming loose).