What is the purpose of the tapped holes in the rail?  

Thinking about replacing the threaded screw in the tripod ball mount below with a screw already compatible with the rail but want to know what they were original intended for.  

Thanks

Thanks.  Seems like I will be able to lock directly onto the quick release plate and save the need for a mount.  MRP just keeps on giving.

Another option I just came across:

Kind of a vestigial thing really. KAC/LMT have always worked together and the threaded holes were another method of mounting things to the rail that weren't already weaver or M1913. The thread size is 1/4" - 20 TPI. The only thing I can think of that the US Mil used/use that attached to them is the SOPMOD M203 leaf sight. KAC made/makes a direct attach PEQ/PAQ mount, and I believe a sling swivel that fit in those holes. I have seen people direct mount a harris bipod to the rail by removing the attachment mech. and attaching it with the proper size screw and washer.
Dustin

Excellent info.  Thanks

It just so happens that 1/4-20 is the standard thread for cameras as well.  Plan to let some kids take their first shots with this set up (300blk subs) soon.

So far have only spent just under $50 on the tripod and just over $50 on a more robust ball head (pictured earlier up)  that is on the way.  

Believe the plate on the ball head mount is aluminum.... could use a slightly longer screw also.

"Say cheese."

How long do the batteries last?  Single color or multi color.