The 35-300 prototype barrel had no markings.
Roy the 450 I built is based off a standard receiver starting life as a 243 win. So the receiver looks exactly like your .284 having both the snap ring cut and holes for the screw. So from the factory one side comes threaded and the other is just a through hole is your off side tapped for a filler screw?
The snap ring groove needed to be very exact, special tooling and fixtures purchased. It was done on a CNC mill with a very experienced machinist at the helm.
I don't want to change that rifle of yours.
The cross screw on the 284 is just a standard cross screw, no filler screw.
I've also got the 30-284 99E it wouldn't be a big loss to make that one a 450.
