What we have here is a post WWII German P-38 holster. I believe your friends is stamped with the manufacturer and date: "C.RIESE; BERLIN; 1960/4".
Walther retooled for new P38 production since no military firearms production had occurred in West Germany since the end of the war, knowing that the military would again seek Walther firearms. When the Bundeswehr announced it wanted the P38 for its official service pistol, Walther readily resumed P38 production within just two years, using wartime pistols as models and new engineering drawings and machine tools. The first of the new P38s were delivered to the West German military in June 1957, some 17 years and two months after the pistol had initially seen action in World War II, and from 1957 to 1963 the P38 was again the standard sidearm.
Your friends holster dated April 1960, falls right into the period of 1957 to 1963.
In late 1963 the postwar military model P1 was adopted for use by the German military, identifiable by the P1 stamping on the slide. The postwar pistols, whether marked as P38 or P1, have an aluminum frame rather than the steel frame of the original design. Starting in June 1975, the aluminum frame was reinforced with a hex bolt above the trigger guard, and a slightly modified, stronger slide design was introduced. During the 1990s the German military started replacing the P1 with the P8 pistol and finally phased out the P1 in 2004.
After phasing out the P1 in 2004, many P1's, some used, some unissued were imported to the US. Along with these P1's many postwar P38 and P1 holsters were imported as well. Some P1's were actually sold with the earlier postwar P38 holsters.
In 2006 I bought a surplus German P1(dated 4/79, that was unissued). It came however with a holster like your friends, but a later P1 with an illegible maker/date stamp. In 2006 I also picked up a Mauser BYF 44 WWII P38 that was in a postwar P38 holster just like your friends, made by C.RIESE dated Sept. 1961.
These holsters are not worth much, someone has 15 available on Gun Broker (
https://www.gunbroker.com/item/894915581) right now for buy it now of $15.00 with hand picked for $25.00. Seller states dates of 50's, 60's and 70's so looks like this was the standard P38/P1 holster for decades.
Here are pics of my postwar P38 holster and P1 for comparison and cause people here seem to like pics.