I have a special sling for my Jaeger, It unique stock fittings. Like a button on the butt, and a full band on the stock new the end of the barrel. Jaeger are generally 31 inch barrels.
For the standard ML like my Thompson Renegade, I have a QD one inch nylon with rubber grip.
I don't own or like the longer barrels for the areas I hunt, but my buddies with the long rifles generally dont use a sling.