Anyone have access to this clamp? Unlike those ugly common worm gear clamps (like these), this metal band has a bolt and a pass through (on the other side). From the looks of the design, it shouldn't be very hard to drill out the old bolt and swap it out with a standard 1/4 x 20 threaded bolt making it easy to mount accessories to your 15mm Rails. The range for these clamps vary, but there's a few that fit 13mm-16.5mm and some that fit 15mm - 17.5mm. I'll probably pass by a local auto store to see if these type of clamps are on the shelf, and hopefully they work out since you can get a pack of 10 for under 6 bucks.

10 pack Hose Clamps Effective Diameter Range: 15/32" - 41/64" (13.5mm - 16.5mm) for 3/8" Hose