I've got a mini Docter-style red dot sight which came with a pistol I bought a while back and I don't really have a use for it. It's quite dinky, only about 2" long, and looks a lot like this I was thinking of mounting it on the top of my scope and zeroing it in as a target finder. Would it be legal? I can only find reference in the BFTA rules to "No separate device, designed specifically for range-finding may be used." and this is not for range-finding. I don't have a big problem finding targets; once in a while in a dark woodland course I might waste a few seconds trying to find one. It's more for the hell of it really, but only if I can find a cheap 30mm tube to weaver adaptor.