Spring air walk-in scope

The adjustable mount Markhooper mentioned is the RWS "C" mount. I have one on my D48. An excellent setup, but it's no longer made.

I had scope creep problems with a UTG scope on my HW50S. Bought a pair of Sportsmatch medium rings and problem solved. They clamp down good and tight on the scope tube, and they have a recoil stop screw to prevent slippage on the mount rail.