In the Best gun category, the maker would build what the customer wanted. GB Evans Purdey he inherited from Dr Norris was alight bird gun but had a Purdey nose and sideclips to action. When a gun was built for heavier loads it was often given some extra locking support regardless of whether it was needed. I had a WJ Jeffery with Purdey nose and somewhere I read they used that not for locking support but it stabilized the ejectors better. I don't like the Greener crossbolt but think the screwgrip action or hidden third fastener are cool. Now I want to know if the top extension on a Dickson RA is supposed to help with lockup.
Why don't you like the Greener crossbolt? Just curious.
My Cashmore BLE Paragon has a hidden 3rd fastener. It's a light 12 gauge proofed for 1.25 oz loads. I'm happy to have a 3rd fastener whether it is essential or not. I've certainly got nothing bad to say about Greener crossbolts either, at least three of my current guns have them, all from different makers. I'm not to hot on doll's heads, but no particular reason why. Just don't care for them so much and sold the one I had.