Simply put, veterans purchased muskets in mass for various reunions and GAR parades, most of these came from Bannerman and Stokes Kirk. These were weapons that went home after purchase and not stored in a GAR Hall.
Get in touch with Yale and find out where the 1864 guns went, quit messing with collectors and supposition. I still contend that the goop on the inside of the lock was for sea service and these were Plymouth rejects. 1864 no states or governments needed rejects, Colt was having issues finding homes for perfectly good inspected and interchangeable muskets. There are so many 1864 perfectly conditioned Colts around today it's incredible; I have a completely unfired one with grease still in the nipple.
Since you have three of these, there is no doubt you want to justify what you paid, but sometimes you just can't fit that square peg into the round hole. I learned the hard way many years ago and jettisoned pieces that I just knew had a tremendous story, not......