I've owned 2 Sightron SIII 10x42 MMD scopes for a few years now. I use one for HFT and the other for hunting. As Greg has said, the only downside are the elevation and windage turrets, which can be moved very easily. There are two modifications that overcome this problem though, cost next to nothing and improve the turrets dramatically. The glass is amongst the best out there. Fantastic light transmission, brilliant clarity and excellent definition. The reticle is close to perfect for my needs. Build quality is on a par with any other £500 scope.
Founder member ~ Fort Airgun Club
Air Arms HFT500, Sightron SIII 10x42 MMD
Air Arms Ultimate Sporter, Sightron SIII 10x42 MMD