Damage to tank fire control systems

[Mustang]

I've noticed in the game that a tank will ocasionally get it's main gun knocked out by a large-calibre hit, but this isn't a very good way of representing fire control systems knocked out. It seems to me that there is a pretty good chance of a tank's fire control system being knocked out in combat, considering that the gunnery sights are made out of glass that can be penetrated by small arms fire (it actually lists this as anti-tank technique in a US Army manual). Once you knock out the gunnery sight, a tank is practically worthless and blind, except for a few modern tanks that have two systems (one for the laser range finder and the other is a backup manual "battlesight").

This would probably a major part of tank combat in real life, as I'm sure at very least 10%, and probably more like over 20%, of the time a modern tank gets hit it's laser range finder will get knocked out by shrapnel or a direct impact. If you want to keep it simple, you could then halve the fire control rating of the vehicle to reflect this. Or, you could give each tank two FC ratings- one for the laser range finder system, and the other for the battlesight.