I looked up Charles, James and Thomas Herron and didn't find any who matched.
Please be advised that the records I am looking up only include those who applied for a pension.Because their names do not appear, it does not mean they didn't serve only that they didn't apply for a pension.These records are mixed up with the Civil War Pension records.For some reason, they (civil war and spanish american war pension records) are together in the archives.
Have you tried NARA?The National Archives might be able to find the records if you have dates of birth and locations.
Most of the 47th NY Volunteers came from Brooklyn.
Also, try a google search for the 47th Regiment, NY.I know they have a web site.