Since many 6-lbrs. were bored out and fitted with a rifled tube liner, converting them to 12-lb. RMLs of the James pattern, this model can do service as a James rifle.
The gun model and figures are by Stone Mountain Miniatures.
Contemporary sources list the following frontages for typical Civil War batteries (depth in each case is 47 yards):
Mounted or horse battery of 6 guns (3 platoons): 82 yards (typical US)
Mounted or horse battery of 4 guns (2 platoons): 62 yards (typical CS)
In my rules, the ground scale is 1-in. (25mm) = 100 meters. Most 15mm models cannot be reasonably accommodated if these frontages are adapted to the ground scale, so I suggest using a 1-in. x 1-in. base for a 4-gun bty. and a 1½-in. (front) x 1-in. base for a 6-gun bty. The 4-gun bty. has 2 figs. to represent the 2 ptns. or sections; while the 6-gun bty. has 3 figs.