Hi, Dmitri;
Per the drill manual, cannoneer number two; the bareheaded artilleryman holding the next round. As I mentioned previously, it gives the casting a “Wild West” look. But this is just my opinion. Working an ACW field piece is a hot, sweaty, nasty job, especially if you are working around the muzzle, as cannoneer number two would be. I would think wearing a hat or cap would be preferable, if only to keep sweat out of your eyes.
I’m not a big fan of the print you used as a reference. For example, I highly doubt a mounted artilleryman at full gallop over uneven terrain could hold a pipe in his mouth without losing it or breaking a tooth 😉. So there is a lot of artistic license in use.
Once again, all this is just my opinion, nothing more.