I refer to App. C "Small Arms Usage by Regiment" in Coates and Thomas' 1990 "An Introduction to Civil War Small Arms" publ. in Gettysburg by Thomas Publications. The authors compiled Appendix C from ordnance returns and ammo requests in Record Groups 94, 109, and 156 in the National Archives and Records Administration, Washington D. C. They state that their lists of small arms "represent the 1863-1864 time period" and warn the reader that "many regiments exchanged small arms at least once during the war."

That being said, Coates and Thomas state that the 10th Ohio Infantry Regiment was equipped with Enfield Rifle Muskets .577 caliber. They do not list the second Ohio regiment you mentioned.

Bruce Nichols