Thanks GG375.... I have started down the EAW route today and discovered similar in their catalogue. A 3 claw system.
I'm in touch with a German retailer who can ship to the UK.

If I fail with EAW I'll have to start on Recknagel...it's all quite a trawl through their pages though.

The front barrel ring has to be soldered the rear is not so complex.
I'm awaiting just a little more info from EAW, but they're very helpful as long as you know the correct questions to ask.

It's a 3-hooked claw mount for Mannlicher-Schoenauer rifles.
Front rings are available from dia 1"/26 mm to 80 mm for almost every bell size.
ATTENTION: this mount requires a lot of fitting labour!! Kind regards, Monja

The above is the initial reply ref a similar fitment to yours.
Cheers, deeangeo