Prone and FT ...

So off the elbows and nothing supported forward of the elbows and butt off the ground in the shoulder.

That position can be very solid, as seen in 50m prone shooting, with the use of a sling, but in FT the targets are not all the same height from the shooter. So a well set sling would not accommodate all targets from the prone position.

... then there's the obstacles in the way to the target ... grass, fallen logs etc.

I still reckon if someone really put the time in then they could shoot prone with a sling and do really well despite the changes in angles.

It's probably as much to do with ( as mentioned above ) how comfortable sitting is, on a big padded bag, for the average age FT shooter.

Equation ... ( Average FT shooter age / Fitness level ) x Prone = Ouch ... Me back!