Here is the page from the 1908 AKAH (a wholesaler) catalog relating to Sauer & Sohn "Tell'' rifles:

IMHO this rifle was chambered originally for the obsolete .22 Winchester Centerfire blackpowder/lead bullet load. "Rand" only means "rimmed", "rimfire" is "Randfeuer". But this is easy to check: Was the firing pin altered from rim- to centerfire? The .22 WCF case was later called 5.6x35R Vierling in Germany and loaded with smokeless powder and jacketed bullets up to a 40gr bullet @ 2600fps load. Several years later several Americans essentially did the same thing. Their efforts resulted in the .22 Hornet. The original BP .22 WCF load was plagued with short bore life due to the tiny, hard to clean bore, corrosive fouling and some neglect.
So this rifle was apparently rebored after a short time to one of the low-power, about 8mm cartridges. This may be the 8.15x 46R, the 8x 48R or some other. Don't forget the .32-20 WCF, which was called an "8mm" also by the contemporary AKAH catalog. Only a chamber cast, preferably using Cerrosafe/Wood's metal or sulphur, will tell the truth.
The sidelever may be a special order item from the S&S factory or it may have been made as an "aftermarket" item by any well-trained country gunsmith.
The patent numbers were just applied for advertizing purposes, to impress possible customers. This was a common practice, not only in Germany, but in America too.