The pictures I posted in the other thread about the MTR and the carbon ring show how short the lead is on that rifle. The ammunition is engraved by the rifling in that barrel.
The older rifles appears to be simply freebored for a little ways before the rifling starts. The reason I say this is there is a short distance between where the carbon ring ends and the rifling begins. It gives the appearance of a smooth metal tube right there.
The freebored section also appears to be the same diameter as the groove diameter of the rest of the barrel. If it is, alignment should not be an issue.
Unfortunately, I have no way to measure all this.
All I can do is check the accuracy the next trip to the range.