Congratulations, Buckstix! You found a very rare, pre-WW1, rifle for the 11.2x72 Schüler cartridge still in original, unaltered shape.
The Peterlongo, Innsbruck, Austria business was run by Richard Mahrholdt since 1898, see:
https://www.germanhuntingguns.com/about-the-makers/peterlongo-johann-of-innsbruck-austria/
(BTW, there is a 1908 ad for a “11.2 mm Peterlongo” Mauser for big game, but apparently still for a 11.2x60 Schüler, + some quotes from German colonial officials. It shows both half- and fullstock rifles like this one.)
Mahrholdt came from the Suhl area and had best connections to many German gunmakers.
This rifle was built on a commercial Mauser, Oberndorf action as sold to other gunmakers. The Mauser serial number 26311 dates the action to 1908. That’s the only German marking I see in the photos, everything else is Austrian. The completed rifle was proofed two times, preliminary and final Nitro proof, by the Ferlach, Austria proofhouse in1909. The barrel is made of steel from the Böhler steelworks in Kapfenberg, Austria. “11,3” mm is the rounded up groove diameter. I don’t know what the “C322” on the bolthandle and “A.R.” under the barrel stand for.
Imho this rifle was built entirely in Austria, Innsbruck or Ferlach. As the Mauser patents were still valid pre-WW1, any gunmaker had to buy an action from Oberndorf first to build a 98 action rifle.