With special thanks to Trevor from New Zealand, and the actual designer of the scope mount, Jeff. The scope is a 3x Meopta.
Jeff wrote: "That highly overrated recoil shift can be overcome with a few drops of Locktite, a good fit is more important.I didn't keep any records of dimensions. I suggest you send him some square-on photos with a metric ruler included,they can scale off the relevant measurements. You might mention in the passing that this mounting was concocted by a countryman of his (here in New Zealand since 1960)”.
Although I'm sure it's ok to share these photos and this info on here, it's probably best not to spread it everywhere (not that someone would like to do that probably). I think Trevor would have to give permission first.
frakor's vintage sniper is my preferred way of conversion of these old rifles. The "long" style period scope on permanent made and fixed scope mounts.
The issue is to use old style scope; old style base and mounts.
In my experience the result only gives minor improvement in sight picture over the open sights. FOV with these old scopes are usually pretty narrow and the cross hairs very thin. They won't turn groups from 1/2" to pellet on pellet at range.
Just putting a modern scope on an old vintage only proves what the particular rifle can do with no sight error. The sight doesn't make them more accurate.
Lastly, for most spring rifles they all are badly behaved when tide to the benchrest. The spring makes them "live" rather than "dead" like PCPs.
Nice idea but in practice these old rifle shoot best standing with their iron sights. Practice with them and they will hold it there. Take them beyond their natural ability and it gets disappointing. We have all tried and there is a hobby in trying to get rifles to shoot beyond the farmyard. To do that really requires a mousetrap that is designed to do so, which generally means loads of weight and spring, port, compression, tuned to achieve the end. Just the way it is.
I knew someone who could bring down a wood pigeon in flight with one of these pre war BSA's. Close range and all in the swing. No one had told him it couldn't be done!