A good friend has one in .177. I've shot it once or twice. As you probably know, the rifle is an RWS54 in a thumbhole stock. He's been using a Leupold 3-9x33 efr on his for 3 years now with no issues. Accurate and fun to shoot, be forewarned the rifle is a beast! It weighs 10 or 11 lbs without a scope if I recall.
John