Peter - the tube is untouched, as is the bracket (I'm assuming a SARCO as it was sold to me by a US friend) - the block is held in place by the turrets (they're in reality just big grub screws) by light pressure (the sleeve around the turret block is a superbly tight fit).
The markings are still 53 scope; the plates under the turrets are fakes - a groove machined in and then deliberately left square - with allen key screws 'holding' them down. The rifle they attach to is also mercifully free of stamps and markings as the whole project was to produce something the public could handle and look through without deceiving them or other collectors. I proudly clain that my rifle is a *unique* No. 4(E) - the E standing for ersatz
Paul