My gr-gr-grandfather Michael Hexamer "enrolled" for a nine-month tour of duty as a private in Co. C, 169th Regt. Pennsylvania Inf., on 16 Oct. 1862, and was mustered in the same day at Camp Howe, Pittsburgh, PA. On 10 Dec. 1862, he was transferred to Co. K of the same regiment. He seems to have spent January through June 1863 stationed at Yorktown, VA., where he was assigned to provost guard duty.
At the time of his enlistment, Michael was 5'3" tall, so he would probably not have been a terribly intimidating presence! I, too, would be interested to know he was "armed."