Not sure what you mean by 'field columns' though but I assume you're using them as 'attack columns' as per the BP rules.
My understanding of the period is that such formations were rarely if ever used. There is a thread on the topic here: -
viewtopic.php?f=14&t=1535&p=14805&hilit=columns#p14805
So the number of columns -v- line is one debate that need not (IMHO) apply to the ACW.
Our club allows column formation attacks only on narrow defiles such as bridges. We class all other columns in ACW as march columns as per BP definitions.
Chris

