These variations make sense, but threaten to become too complicated for the spirit of the game. I am curious if others have tried this one. With one friend we always play that if you start the scenario with no cavalry units, then you can discard the Hit and Run at the time you draw it. Of course the card can become useful if you get a cavalry reinforcement, so we require the discard to be immediate upon drawing it. Which is not quite what the card does.
All special cards are in a seperate deck.
I'm anxious to give this a shot with folks in my group. The concept of rifled artillery was that an explosive shell projectile fitted to leave a rifled bore would have greater range and accuracy than the typical solid shot fired from a typical smoothbore piece, such as the 12lb. These advantages were born out in practice. However, the drawbacks were that rifled artillery pieces were more demanding to make and difficult to maintain and so were few in number. Ammunition for these guns didn't pack quite the punch of their smoothboore cousins among massed troops, though their accuracy and effect against enemy artillery was an advantage.