I seem to recall the range of the 23mm rounds was felt to be insufficient at some point. Swapping the gun could mean a relatively cheap upgrade.
Wonder if the S-60 57mm gun would fit?
Range comparison:
23 mm 2A7 from ZSU-23-4 | | 30mm 2А38 from 2K22 Tunguska | | 30mm GSh-30K | | 57mm S-68 from ZSU-57-2 |
Effective vertical range: 1.5 km/direct range: 2.5 km | | Effective vertical range: 3 km/direct range: 4 km | | Effective vertical range: 3 km/direct range: 4 km | | Effective vertical range: 4 km/direct range: 4.5 km |
Thus the GSh-30K is better than the 2A7 and about equal to the 2A38 but with a much higher rate of fire (though this also means a need for more ammunition). The S-68 is better with range but the ammunition size probably causes issues. Mind you, the recent 2S38 ZAK-57 Derivaciya PVO (see below) returns to the 57mm gun, albeit in a newer with an effective vertical range: 4.5km and direct range of 6km supposedly
Either way, I just thought a version with a 6 barrel, 30mm gun would look cool and different.