Did you happen to buy this on gunbroker last spring?
(You need to Login or Register to view media files and links) There was a Hoch rifle that sold then and was advertised as a 30 Swartz.
There are two different 30 Swartz cartridges, one based on the 357 Maximum case, the other on either the 30-30 or 32-40 case. Dimensions for those are in the back of “The Modern Schuetzen Rifle” book. Both are longer than 1.600”. Both used a .308 bullet. Both are basically a straight taper from base to neck. No none tapers .200” line at the base. 32-40 dies cut off to the appropriate base diameter work well to form the cases.
There is also a 30-160 Hoch cartridge that I have seen mentioned, in the same book, I think there’s was a photo, but no dimensions.
Maybe that ring size some bells for others that were shooting at that time.
Edit to add.
Looking at list of cartridges in “The Modern Schuetzen Rifle”, there are a number of cartridges that are close. A good chamber cast is in order.
Looking at some dimensions a 7mm Brewer is a 1.54” case based on the 30-30, Charlie Dell’s 333 KR was 1.5” long. Either of those necked up or down to 30 caliber are possibilities. Even an 8.15 X 46R is close.
At the time that rifle was made, a lot of people were experimenting with 30 caliber cartridges. Without a marking, you may never know for certain. Forming some brass for it when you have an actual set of measurements shouldn’t be too hard.
Found this looking around
(You need to Login or Register to view media files and links) (You need to Login or Register to view media files and links) Seems to have been a popular chambering