IOR offers superb scopes. No doubt about that. I have been in the market for the Crusader 5,8-40 for my FX Royale 500, but ended up (for now) with the IOR Recon 4-28. The Crusader is on backorder - unknown delivery. Both scopes have 40 mm tubes, and this have given me som headache. Especially because of the relatively high rings the Royale demands due to the magazine on top of the breechblock.
Many turndowns from different retailers/detailers all over the world, and IOR in Romania (offers 40 mm heavy duty rings), do not deliver to Norway (!). Not even rings.....
I see 40 mm rings and one piece mounts listed, but they are typical medium/low height, and "high versions not in stock" is the refrain . Except Optics Trade who sent me a pair of Contessa 40 mm rings that came in today. They are 14,5 mm high, flushing the tube by a hairline, but not enough to go clear the housing. But the eye distance/relief to the lens is perfect nevertheless, so I got lucky with that one I guess.