Interesting. If there is a gap in the front between the base and the barrel, that suggests to me that the base is probably still parallel with the bore. Hard to say from here.

At least you know how to shim to fix the problem in the short term.

And I'm not stirred up, I'd really like to know what's wrong with T/C barrels that makes them shoot too low with scopes. One thing is for sure, it isn't barrel taper. Could be something else though.

It would be interesting to see where a bore laser sighter would project a beam in relation to your crosshairs when the scope is set to its center. That would be telling I think. Do you have access to a bore laser? They do make them for MLs.