Assuming we are talking about a reproduction gun, Dixie Gunworks 1995 catalog shows a 1863 Springfield that was made in Japan.
Although this may be a well made gun, the catalog says the lock will not interchange with an original 1863 so if the lock needs parts there might be a problem.
Dixies 2003 catalog also shows the Japanese 1863 but in addition it shows an Italian (Euro Arms) version which may be easier to get parts for.
Dixie also shows a 1861 Springfield made by Euro Arms in many of their catalogs.
Generally speaking, the Italian guns are well made and should be a good addition to a persons collection.
Speaking of triggers, the Military guns originally had very "heavy" triggers and the reproductions didn't do this any favors by improving things.
Because this heavy trigger feel is part of the guns design, there is little one can do to improve it much.
To the best of my knowledge, all of the .58 caliber reproductions are recreations of the "Rifled Musket" so the barrels should be rifled.
Most of the smoothbores were in .69 or larger calibers.