To be honest I feel sorry for the mount manufacturers. The machining of dovetails on air rifles (especially springers) has never been properly standardised, with the result that you might be faced with a dovetail size anywhere between 9mm and 16mm, with quite few half mils in between. The depth and angle of the cut may vary as well. All too often scope mounts don't quite fit and are over-tightened to compensate, and being usually aluminium, they don't cope well.

It's tempting to think of mounts as a pair, but in reality they're being churned out in their thousands - we just happen to need two at a time.