Spencer Springfield Armory Musket Rear sight

[Dana]

From what I have seen in pictures, the Springfield Musket Spencer has a different rear sight, does anybody know if this is a special sight used only on 1871  Spencer's or is this just a Springfield sight, is there a name for this type of sight from Springfield.

Thanks Dana

[Herbert]

The Springfield conversion of carbines to muskets was done on the the Burnside 1865 carbines by fitting a new Springfield .50 cal 3 groove barrel ,the rear sight fitted was the model 1868 military sight,the earlyer conversions were 1860 rifles relined with 50 cal liners and modified with Stabler cutt off and spring asist extractor,the hammer and frame were also modified to 1865 M shape,the sights were left the same as was on the original 1860 rifle