I was rather intrigued to read some things earlier today that mentioned how the 20mm cannon loadout on the I-16 was mainly intended because the 7mm guns were ineffective at strafing ground targets -- especially armored ones (light tanks, halftracks, etc). The guns had been evaluated many many years prior, and had been discarded as not needed.
The guns were rather easily put back into the airframe, since the work had already been done at one time and most of the kinks worked out. This allowed the I-16s to much more effectively strafe convoys and ground units. The I-16 types that used the 20mm then primarily used them only for ground attack. They were mostly belted with a mix of HE and AP. Even so, the limited ammunition made them rather hard to supply and ammo was scarce. In many cases they couldn't use the 20mm for lack of ammo (construction and distribution were a royal mess for years in the Soviet supply system).
This lack of ammunition and specialized use of the 20mm loadout is why they also developed the 12.7mm gun option for the I-16. That actually came later! It's because they didn't have much more than 4x7mm loadouts, and the 12.7mm was a major improvement over that.
Even when you look at photos, almost every fighter variant of the I-16 has the smally nubs of 7mm wing guns. Downed planes, captured planes, planes repaired and put into use by enemies, all still have the 7mm guns. Of the many thousands of I-16s made, the 20mms are actually somewhat rare. Even the soviet pilots with the talent to get multiple kills on german pilots used the 7mm loadouts.
This is a far cry from how they are used in Aces High. In here the cannons are used for everything, when in fact they were not the main armament.
It paints an interesting picture. It's also interesting info for FSOs and scenarios. I recall an FSO where I-16s were put up against Ju88s not long after the I-16 introduction to the game. They all used 20mm, and they did rather well for themselves. I don't think they would have done so well with 7mms only. It's doubtful the 20mm was ever used that way on the I-16. In fact, it's much more likely the 7mms (and later 12.7mms) were the only weapon the I-16 used to down enemy craft. Realistically, the 20mm loadout option should be disabled for when the I-16 is used for fighter duties in FSOs and scenarios, and used only for ground attack duties. CMs have the ability to disable certain loadouts from being used in the SEA (for those that don't know).
Food for thought.
