It needs a button that stops it from firing at any infantry (or not shoot infantry at all). Why would you shoot an armor piercing high velocity round at infantry anyways?
Definitely. I feel this way about all the anti-tank guns, actually. They tend to just shoot and give away their positions.
Oh, and about the pop: if it gets decrewed and you then re-crew with pioneers (1 pop per man) the pop of the re-crewed gun is much lower. When you build the gun it spawns a gun crew. Each crew member costs 4 pop and 30 manpower to reinforce. The population cap usage of the gun reflects the units that are manning it; ie if you re-crew with pioneers or grenadiers, the pop cap usage will decrease, since individual grenadiers and pioneers use only 1 pop. Pioneers are also cheaper to reinforce (25 MP v 30 MP).
Also, isn't it only 12 population or did that get secretly changed? Guess I'll have to try one soon