Your barrel sounds like it may have been imported by an importer who called themselves Springfield.
Over the years we have seen hundreds of importers come and go. They usually import from one of the several companies that have made muzzleloaders over the years.
These manufactures are usually located in Italy or Spain although Belgium, Germany, England, India and Japan have also contributed.
As all of the countries except the U.S. and Japan require proofing of the barrel, look for proof marks to learn where the barrel was made.
Italian barrels will have the letters PN with a star in a circle and a small shield with a star above it stamped on it.
All of the muzzleloaders made in Spain seem to be made by Ardesa, makers of CVA and Traditions guns.
The Spanish proof marks usually have a number followed by Kp/cm or similar letters.