Many Topwar texts are crap even when posted in their native Russian language, and further use of Google translate does not help them any.

So, topwar is the Russian equivalent of Business Insider?;)

Also the G11 had originally been designed by mauser, with a 10 rpund rotary magazine.

Another protoype by IWK had 3 barrels, and could fire a volley of all 3 shots

If you refer to the Bundeswehr G11, it was not "originally designed" by Mauser. 

The real Mauser design (at least the metal parts, the plastic housing has dissolved itself) can be viewed in the Bundeswehr technology collection (WTS) in Koblenz. By the way, there was another design, by well known Anton Politzer of Diehl, which had three barrels and a rotary element containing one chamber for each barrel. 

At the time, Mauser still was a subsidiary of IWK (former DWM). There were no competing designs Mauser versus IWK. The development center (Entwicklungsanstalt, origin of the 27 mm BMK gun and cartridge) was located at Oberndorf and nearby Schramberg-Sulgen. 

Anyone have the specs for the funky Soviet space autocannon R-23 that test shot in Space in but deemed unpractical due to recoil requiring the space station to use a booster to keep the orbit when firing.

http://russianammo.org/Russian_Ammunition_Page_25mm.html#9a