No. 5 Mk1. Oddities?

[Thunderbox]

Trouble is, you can see that any marks produced by the illustrated barrel-straightening would be perpendicular to the bore, not aligned with it.

The marks must have either come from a different type of jig, or from a different process altogether.

This is another "worn" No5 barrel I happen to have to hand. This one has distinct longitudinal banding or striations visible, also only evident in the remains of the Suncorite and not detectable to the touch. This is a "D in a circle" draw-lapped barrel, so maybe these are all types of clamping marks from barrel operations.

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[jmoore]

This is a "D in a circle" draw-lapped barrel

Draw lapped on the inside and possibly draw filed on the outside? It's surely what one would expect to see- having done the same procedure a few times on different things. Could also be a minor vibration from turning the OD with insufficient support. Oddly, that sort of pattern is quite common on wartime production M1911 pistol barrels. The directionality of the tooling marks will tell the story.

[XL39E1]

That was one of the pictures I was looking for, If you have a round barrel resting on two hardened steel flat bars and then strike it like the illustration then you will get the marks in line with the bore! Just try it! If the Barrel was resting one the sharp edge of the blocks the marks go the other way.