Hi, Hawg and guys,
I have a problem with those so-called "artillery models" of the rifle-musket, especially the Special Model 1861. I have seen three or four that were obviously cut down muskets, and didn't even have the same barrel length. The sellers insisted that they were "artillery" muskets, but when I asked about documentation, they were unable to provide any (one suggested I book a trip to a warm climate).
I have some backing in this from Flayderman who has several notes cautioning about so-called "artillery muskets."
It is my belief that there were no artillery muskets of those models, and that all the muskets called that were simply cut down standard muskets, many of which were made up after the war for military schools and the like, or for export to countries whose troops were of shorter stature than American soldiers.
FWIW, the standard small arm of the artillery in the Civil War was the saber or the short sword; these were not worn but carried on the ammunition chests.
The weapon of the artilleryman was his field gun. Some artillerymen carried personal pistols, but any such weapon would have been pointless, since a gun crew wasn't large enough to fight off even a small enemy cavalry or infantry detachment if their infantry support failed.