Hi,
It could be that when the rifle was being built, the end of the barrel that had the makers marks could have been cut off for some reason.
Back in the 70's we did not really care who made the barrels ( ignorance??) as long as they were round (inside) with square (octagon) outside, we were happy.
We were so happy to see and use the Dixie catalogue.
Some of the early barrels were drilled way off center, so we had to align the barrels so that the off center was up or down, as long as it was not left or right.
The gun barrel makers of today are far better than early Numrich or early Douglas.
Douglas barrels were renown for their quality ( quality of rifling )
Many Numrich barrels did not have a makers mark on them.
Fred