To continue the discussion a bit, I haven't been able to find any documentation regarding replacing the folding long range sight with the block sight prior to shipping the arms to North America. Perhaps Mr. Don Dixon will have some insight on this?
J.
Ah -- the issue of rear sights on Civil War Austro-Hungarian Army (k.k. Army) weapons.
Lorenz's Muster 1854 rifle musket design was superior to that of the Model 1855 Springfield rifle/rifle musket and the Pattern 1853 Enfield rifle musket, both of which had fixed rear sights, in that the rear sight of Lorenz's gun fit in a slot cut in the barrel. When the Muster 1854 rifle was proofed and targeted at the Vienna Arsenal, Lorenz's design permitted the rear sight to be moved in the sight slot to align the sights accurately with the target before the sight was staked in place. With the U.S. and British weapons the soldier had to hold off to adjust for misalignments in the structure of his rifle musket. But, it was also easier in Lorenz's design for the rear sight to be knocked off of the gun, and Muster 1854, Type I and II, rifles without rear sights are not uncommon.
Several thousand Muster 1854 rifles with Pattern 1853 Enfield long range rear sights were inspected at Liege, Belgium, and imported by Herman Böker and Company for the Federal Army. They are the only ones that I know of that went through a program of having new rear sights placed on them before importation. They were probably captured by the Sardianian and Imperial French Armies from the k.k. Army in northern Italy during the Second Italian War of Independence in 1859, and they were refurbished by O. P. Drissen et Cie in Liege.
I have seen replacement rear sights of somewhat different designs, which are conceptually similar to the one on brcampbe's Type II rifle. To make an educated speculation, if the sight is Civil War period it was probably an expedient Confederate replacement for a lost rear sight. But, I by no means discount a post-war expedient gunsmith replacement for a missing rear sight either. Close-up photos of the rear sight from several angles would have been interesting.
Pre-System Lorenz weapons were rebuilt/refurbished in significant numbers prior to importation, and the rear sights on them are all over the place.
Regards,
Don Dixon