To somewhat collate the responses
A tank with an autoloader has these advantages . . .
- One less crewman to feed, clothe, train. In a large force, such as the former Soviet Union/Russia, this can really add up to a huge savings in cost.
- The ability to make a smaller tank (And therefore a smaller target). Notice that Soviet/Russian tanks are traditionally smaller than their Western counterparts. This can also be transfered into more of the weight of a given-sized tank being dedicated to armor, fuel, equipment, etc.
A tank with an autoloader has these disadvantages . . .
- It would appear that they have a slower rate of fire than manually-loaded guns. This is due to the ammo type having to be selected, on earlier designs the gun tube had to be elevated, the carousel spun around, and the shell (and on some designs the propellant casing) mechanically shoved into the breech.
- Although I believe the newer designs have addressed this, autoloading designs must have the ammuntion in a position easily accessed by the mechanism. This lead to the deadly carousel arrangement where the ammo was stored in the floor of the tank, exposed to the fighting compartment.
- An autoloader is a mechancal device devised by man, and therefore just as likely to fail/break down as any other mechanical device.
- One less crewman also means there's one less crewman to help maintain the tank. I believe if you ask a tanker, he/she'd say that a good portion of their day is spent working on the tank itself. 3 instead of 4 crewmembers means the work must be spread among less people.
- Undoubtedly addressed in newer designs, but it's my understanding that the earlier versions of the Soviet/Russian autoloader could easily grab the hand, arm, or clothes of anyone who happened to be too close.