I guess it depends on how you define "gunline". Any list that includes a few war machines is not necessarily a gunline. Gunlines basically involve the following strategic concepts for your army:
1. Shoot the enemy and hope there's nothing left.
2. Shoot the enemy and mop up what's left.
3. Shoot the enemy and hold the line.
4. Potentially others, depending on how you decide you want your force to defeat the enemy.
Now, in order to be a proper "gunline", a force will then include a heavy selection of ranged tactical capabilities. In other words, you'll have at least a few war machines and probably 3+ units of ranged infantry. If your force includes a single significant unit of dedicated combat troops, you might still be able to define it as a "gunline". Once you start adding other significant tactical capabilities, it ceases to be a gunline any longer and may be referred to (by colloquial convention within the Dwarf community, at least here at Bugman's) as a "conventional", "old-line conventional", "traditional", or "hybrid" force. Any of these other designations are often assumed to be "gunlines" on the basis that they involve ranged tactical capabilities as a significant or primary means of supporting the force's strategic concept, but the reality is that they are not actually "gunlines". For example, a Dwarf force that includes 2 Cannons and 2 Master Engineers accompanying 2 Organ Guns is technically not anything close to a gunline.
Of course, such rules are not hard-and-fast, and the actual definition of "gunline" is not my sole purview. Regardless, a good rule of thumb is, "A few war machines does not a gunline make."
So, without knowing what you've been using in your games (which you interpret to be a "gunline"), I don't know exactly what you mean to ask. I assume you're simply looking to minimize the reliance of your force on ranged tactical capabilities. If that's the case, you're probably best off determining how little shooting you can get away with while still giving your opponent enough incentive to move towards your lines in order to engage your units in close combat. I'm not sure there's any simple or easy answer for that.
Edited by Swordthain, 10 February 2015 - 08:05 PM.