Chances are you may never know for sure. Period documents do not always get specific in reference to firearms. For example an 1864 reference to "Springfield rifles" could be one of several models; 1855, 1861, 1861 Special, 1863 or 1864. And if an 1861 Model is it truely a Springfield or a contract piece? Belgian guns were often copies of French ones so period documents will often refer to a Belgian musket/rifle as a French model or visa versa. And records for a cavalry regiment might just note that they were issued "carbines" on a certain date.

If there is a regimental history of the 22nd IND it might contain some info about arms. A photo of a soldier might help too, even what type of bayonet he has may prove to indentify a firearm.

Despite its detractors the Lorenz was well rated by the Ordnance Department and this may help answer your question of why it replaced the "German rifle."

You can also check what other Indiana regiments were equipped with at the same time as the 22nd, or what arms the regiments the 22nd was brigaded with carried. All these little tidbits might offer a clue.

In the end, be happy. At least you have a pretty good clue of what this regimnemt carried as opposed to most other units! :)

John Gross