Totally agree Warbler.
I'm also an old rifle shooter from the .303 days and I also have the Army's Crossed Rifles marksmanship award.
Even shooting prone with both elbows on the ground, we used to use the sling for additional stability.
These things don't cost an arm and a leg so I may even try one myself to use with my monopod.
Agree Terry, a monopod is not a big help with BIF. I started with an average monopod head but found it tended to droop, so I upgraded to a Kirk and when set for the weight of your gear it's good enough to stay where you point it.