I don't know. I read that there was a shortage of rifles at the start of the
C.W. and use of personal rifles was not uncommon, but that was Wikipedia.
I have not researched the subject. I'm sure others on this forum have some
knowledge about this. Wiki stated some numbers of what the Army had available
vs what was needed at the time. "When the American Civil War broke out in April 1861, neither the North (about 360,000 small arms) nor the South (about 240,000) had enough weapons to fight a major war.[1]:75 Stockpiles of rifles and handguns carried by individual soldiers were limited. As the war escalated those arms stockpiles were quickly diminished.[2] Soldiers were often forced to use older smooth bore and flintlock muskets, which had been considered to be obsolete, simply because the newer rifles were not available in sufficient quantities. Many soldiers were forced to use their own personal hunting rifles, which were typically Kentucky or Pennsylvania type rifles. These rifles, while more accurate than smoothbore muskets, had been designed for hunting, and fired less deadly smaller caliber ammunition."
They site "Civil War Firearms: Their Historical Background and Tactical Use" By Joseph G. Bilby " as reference.