79,000 rpm/88 guns = 897.7 rpm/gun, but Wikipedia has the PPSh-41 rate of fire listed as 1250 rpm, which would make this 110,000 rpm.
But, that drum magazine only has 71 rounds, so you could get 110,000 rpm for about 3 seconds (71 rounds/1250 rpm = 0.057 min = 3.4 sec) ... and then what? Fly back to base so you can swap out 88 individual drum magazines? And also do maintenace on any of the guns that jammed?
Some real redneck engineering energy.