Remembering that wind and other factors will contribute to the bullet would mean it would be difficult to land a shot on a commander. 2nd to this, you would probably be capped to a certain amount and you would probably have to go solo or with a small group of people (no more then 4 people). This would leave you vulnerable to cavalry which could easily take you out. Not to mention it would probably be a long reload to help balance it. There are probably more options, just can't think of one.