I took a tip from a Chinese underlever and mounted simple hardware on the sides of the stock. Got leather straps from the shoe store and used a leather screw on each end. Choose your own length and punch a hole. you can set it so you can insert your left arm in the strap for a positive hunting hold. I did it to RWS 40, 46, 34, and R9 Beeman. Cheap fix and it works. Throw the gun over your right shoulder where the butt will be vertical and go mow the yard, stop and shoot a starling .