Yes, I have heard the 45/410 barrels are more of a novelty then a practical tool. Plus 410 bore shotgun shells are too expensive.
Sounds like you have a hotshot barrel, made for the plastic shot cups loaded in the 45 Colt case and not 410 bore shells. If so, then the chamber shouldn’t be too long. Have you shot it at all?
Merry Christmas,
yooper77