The Confederates captured the 91st's Headquarters Wagon, presumably including the books, in November 1862, at Snicker's Gap, Virginia. Two Confederate accounts of the capture exist, along with Thomas Walter's account of his capture when he attempted to retrieve the wagon.
Two bits of evidence suggest the books were lost again after Gettysburg. First, the Regimental Orders book begins with records from June 1863. Second, on 18 August 1863, Tayman asked company commanders to send him a complete list of commissioned officers, with changes since the beginning, "to enable the undersigned to enter them on a New Regt Descriptive Book" (circular, HQ Adjt 91st PA, 18 Aug 1863).