Still sceptical arent you

I wonder when the rifling nows to show up on the outside. But you are right it strange that it can be seen the whole length, but it could also be that the bullet never gets a full engraving.

If the barrel is cut it shouldnt be any stress over the rifling, and if its hammered the stress would be lesser over the rifles wouldnt it. But if the stress is lover it could be that its easyer to print the rifling to the outside as the metal isnt as dense as the surrounding. But this doesent give the answer to why it only starts to show after the mono bullets are shot thru it. It would be nice if someone with a rifle that has this OSR problem could look if its cut or hammered.

Are the old riflebarrels you refer to hammered or cut? I ask as the hammerpattern on the outside of the barrel is possible to see in som rifles (it is let to turn as it goes thru the hammers),but then it selden does follow the twist of the rifles.

btw. does your mirror letter show up after the stampings are done or 50 years later?