Tom... the barrel bending was on my first AR about 1984, and I usually clipped it on between the legs of the front sight tower...it was a thinner barrel AR pre HBAR... we shot on a metallic silhouette range, and shot 10" plates at 200m...all I had for a scope was the Colt 3x on the carry handle, but I could watch the bullet strike from below the rail when the rifle was resting on the forearm, to over to top of the target when pressure was applied to the bipod...never really did any scientific study of the sling, it was a standard factory item, and always thought it was attached in the wrong place.... I traded that rifle in on my first M1A, and ruined a beautiful piece of walnut forend when I went prone with a Harris bipod attached and broke out the wood.... shot the M1A iron sights only... did not shoot much with slings in the early years, as most matches were were relatively close, or had good support positions
my current game rifle (carbine) is fitted with a Knights vertical grip that I use all the time as a monopod, but it is attached to a lone rail on the bottom of the full float tube... I had a good run at the 2009 Ft Benning 3gun sniper stage with a 12th place finish, using a hasty sling and the monopod...the really tough shots at Ft Benning are the standing, unsupported head shots at 75yards... the sling was designed by a friend, and is a 3 point that allows you safely drop the carbine and transition to a pistol if necessary....It falls across your chest without pointing at anything important... I attached the sling with an Uncle Mikes sling swivel to the left side of the full float tube ....for local matches, my short range carbine does not have a sling, too much opportunity to snag it on things, and we shoot awfully close distances on pistol ranges