The July-August 1981 issue has a two page article and a photo of ten members of the "Bloody Tinth". Seven of the men are cradling Enfield rifle-muskets with socket bayonets attached. Not to disparage you grandfather's memory, the regiment was mostly "unruly irishmen" and "tended to be quarrelsome with members of other regiments" Hope your wife thinks better of you. If you'd like a copy of the article, contact me at boatdialatjunodotcom.
Also, a correction; the 1861 and 1863 Springfields were not "rifled-muskets" they were rifle-muskets. The weapons were based on a musket pattern, yet, as part of their initial design, were rifled at the factory before being accepted by government inspectors. Smooth bored muskets, such as the M1842, were sent back to the factory to be rifled. These are rifled-muskets.