General Danner is too generous in his comment. Most of my time in the ACWGC has been spent in developing large scenarios for multi-player use. As such it has involved trying to understand Turn-based play as it is shaped by the game engine. I completed some studies years back involving the rifle, movement and opportunity fire. These are stored at the ACW Engineering site (
http://acwgc-engineering.com/) if you are interested.
Since this thread involves an artillery discussion, I will stick to that. Setting a maximum number of guns in a hex other than what the system will allow depends solely on whether one is willing to employ a house rule. Artillery manuals of the time allocated a 14' distance between unlimbered guns. Allowing for one gun at each end of a 125' span, this would create an 11-gun line. A maximum stack of 12 guns per hex would make sense. In addition the game system allows an unrealistic 180 degree arc of fire for said guns. If pointed generally in the same direction, said arc would be at best 90 degrees with two 45 degree oblique angles which could not be covered short of re-positioning the guns. I throw this in the mix just to illustrate that guns have greater flexibility to deliver fire than they probably did historically.
More directly to Ned Simms' question concerning gang firing, I have actually tested that hypothesis. There are aspects of the game system -- and I am not referring to optional rules -- which appear to me to be vestiges of the Battleground series. The mechanism for firing is one such. For those who have never played the Battleground series, casualties were listed as "hits". A hit caused 25 infantry casualties or a 1-gun loss. With the advent of HPS and individual manpower losses, the dynamic changed but not the actual code for firing. The act of firing is unique code which takes the selected firing unit, the targeted unit, the parameters involved and produces a result. This result is applied and the game moves on. The next time you select a unit to fire, the same series of steps result. Each firing event retains no knowledge of what occurred during the previous fire. The previous results are stored in memory, but these results are not accessed by the firing code.
For example, an artillery unit (or infantry/cavalry) fires at an infantry unit and produces a "hit" of 7 men and commensurate fatigue. This result is applied elsewhere in memory reducing the infantry unit by 7 and adding to its fatigue. Let's assume that the firing artillery unit has a defending infantry unit and the player had chosen to gang fire both instead of each individually. The gang firing is executed as two separate events, not a combination. Let's say the second event -- the infantry portion of the gang fire -- produces a "hit" of 3 losses and commensurate fatigue. This result is applied elsewhere in memory and the total effect is 10 losses plus fatigue. The losses not only reduce the size of the targeted unit, but they are used elsewhere in morale checks.
Applying this to battery vs. battery fire provides something interesting. In order to eliminate a gun, a "hit" must consist of 25 losses. Here is where the concept of unit fire makes a difference. A 6-gun battery is much more likely to register 25 casualties with its "hit", than will a 2-gun section, or another 2-gun section, etc. Each firing is a separate event. Why should a battery have a greater chance of scoring a gun hit than its component sections? It should not, but the manner in which the game works, it does. Occasionally a 2-gun section will score a gun hit, but that requires a random good "hit" in terms of casualties. I solve part of this problem by modifying 6-gun batteries into a primary 4 and sub 2 in an OOB.
The manner in which opportunity fire works presents another disconnect between smaller and larger batteries, differences which shouldn't exist. A 6-gun battery fires defensively with a value of 3 guns. A stack of one 4-gun unit and one 2-gun section will fire, at the most, with a value of 2 guns. The Turn-based system fires by units and only once in all the testing I have ever done has it fired all of the units in a hex defensively as a gang fire. It just doesn't work this way. This gives an artificial (and significant) advantage to 6-gun battery units. Our Rebel readers will agree with this assertion.
Does everything work as I have outlined above? I don't know. Until the workings of the system are documented, or someone else does their own testing which proves me wrong, this is my story and I am sticking to it.
The question of infantry stacking/movement/fire can be discussed further in this thread or in a new one. I will hold thoughts for the moment.