hi,thanks to all who replied to the thread,all info much appreciated.i will try and borrow this sight and offer it up to my classic british springer collection and see what it could fit out of interest,as you say john many guns could be fitted with theses sights.i found a BSA sportsman five rimfire with a ph16 fitted on the internet.one of these little beeezers was my first ever rimfire back in 1973.happy days..cheers all..greasemonkey