This holster design was probably intended to be clipped onto a belt and have the gun be capable being drawn and fired from it. As the ejection port and trigger are still accessible.
The Type 64 is a dedicated suppressed pistol first introduced in 1965 and used in the Vietnam War. It uses a rimless version of the .32 ACP cartridge (7.65x17mm) in a 9-round Makarov like magazine. Despite outward similarity to the Makarov (especially the grip), the design is wholly unique internally. It uses basically a miniaturized AK bolt to allow the shooter to select between blowback semiauto functioning and single shot manual operation. The bolts rotating locking lugs prevent it from cycling when locked, in a very clever alternative use of the rotating bolt system. The suppressor has two chambers, using a combination of baffles and wire mesh as suppressor elements. In addition to standard ammunition, a plastic-sabot frangible load was also developed for use in situations like airline hijackings, and this loading is why some sources reference a maximum effective range of 15 meters.
For all its technical cleverness, the Type 64 is a rather heavy pistol, at 1.8kg / 4 pounds. It was replaced in 1967 by the substantially lighter and simpler Type 67, which weighed only 1.05kg / 2.3 pounds.
Ian's video: [17:46] https://youtu.be/wrLv_2Lf2rU?si=
