It is rumoured that the ZH05 started off with a 3 round magazine fed semi-auto grenade launcher, but that after field trials, the PLA requested the design change to bolt action breach fed to reduce weight and improve the performance of the grenade launcher.
Looking at the gun, you can clearly see the gap where the magazine would have slotted into, had they carried on with the magazine.
I am honestly torn on this, as I think a 3 round magazine would have been very useful in some situations, whereas the weight savings and flexibility in round selection (hell, maybe even the option of having 3 specialist round types to choose from rather than being stuck with a HEDP round type) are also major pluses in other situations.
I suppose, for the primary mission of the smart grenade launcher - to take out enemies in hard cover with perfectly timed air bursting grenades, a well trained soldier could almost engage multiple targets as fast with the bolt action as he could with a semi-auto.
That is because the bulk of the kill cycle in such instances revolves around programming of the fuse. On the ZH05, that is done with the left hand, while reloading the launcher is done with the right.
If you trained so much and so hard that the entirely reloading process is done to muscle memory, you can devote the lion share of your attention on keeping the weapon aimed and programming the point of detonation with your left.
It will be a lot harder than using a semi-auto, but it should be possible to achieve similar fire rates and accuracy of air bursting.