Hey Rob.
If the gun was taken apart to jug choke it, it looks like they just did a mediocre job on the strip and relay. That much difference shouldn't matter. The tool marks seem to line up on the bottom of the breech so it may have just been made "off". How do the inside of the tubes look?
Also, although that tang screw doesn't look right, then neither does the hammer screw on the right lock.

Tom

Carbonation without fermentation is tyranny