The Vasilek looks like it takes normal charges from the powder bags near the fins. They just precharge em before loading them into the magazine.
We also did it with the 60mm when we drop fired it. I forget it has beleive it or not been 20 years and a couple days so I am allowed
But the idea of the 60mm drop firing is, for tactical line of sight firing.
The small baseplate is carried locked, and when needed the gunner slams the gun down, uses the elevation guide and drops rounds down the tube firing using the trigger. The charges on the rounds are not adjusted!
As for hard work manning an 81mm.
Only if it is humbed. Otherwise once the gun is set up you just have to make sure the gun is adjusted back to zero which is usualy a small adjustment <the manual give us like 20 seconds, most do it in about 9 to 12> Again, ammo prep can be done before the fire mission, most fire missions even a fire for effect is usualy about 3 rounds per tube.
And one man can move a 81mm by himself, although, he would not be very fast. A 60mm our displacement method was grabe the whole system and run away a few 100m, the original shoot and scoot.