The ratio of pike to shot would change over the 17th c., initially with there being three pikemen to one musketeer, by around 1640 an even number, and later in the century fewer pike to shot- or, no pikemen at all. The ranks would be somewhere between six and ten deep, and strategies varied: many preferred to have the front rank fire and retreat to the back to reload, the second rank advancing to take their place and firing, etc. Others would have the rear ranks march forward past the front rank to fire. Others, like Gustavis Adolphus, had the front ranks kneel and all six ranks fire a volley together.

But when the opposing sides got close enough for things to be decided by "push of a pike", the musketeers would use their guns as clubs, beating down opposing pikes: or beating down opposing soldiers. On some rather rare occasions the forces would separate, and it was then possible that the musketeers might begin firing volleys again.

Firth, Charles ( 1962) Cromwell's Army