Originally Posted by Jonathan B
The sling is tight when I start. It loosens a little bit with every shot.
You're going to have to rework the sling so that when you tighten it down, it won't come loose. That, or get a new sling that works more for shooting than for carrying.
When I tighten down a National Match '1917' style leather sling, I pretty much cut off the circulation to my arm when I tighten it around my arm (above the peak of the bicep, towards the shoulder).
See (9-10 sec mark):
I place the sling on the arm at pretty much the same height on the arm in both sitting and prone.
The sling never comes loose because when I tighten it down, the keepers/hooks are placed directly in line with the direction of the outgoing part of the sling to the rifle, so the rifle's pull from my body isn't loosening the sling.
See if you can rework your sling type so the sling tensions work against itself.