The operational deployment of the anacronistic rapid fire guns is now reasonably well known - the guns have been used in quite a number of battles so far.
They are mounted on fairly mobile light gun carriages, and formed into mixed 'Spitfire Regiments' with pike and skilled firelocks supporting 3 or 4 gatling guns.
Each Spitfire regiment has quite a big wagon column with it, presumably with ammo and spare parts in it - though the normal soldiery are kept at a distance, and the members of the specialised regiments are hand picked.
IIA Field Agents have not yet been able to infiltrate one of these regiments (mainly because none of the field agents have any military background - they are mostly academic anthropologists or sociologists).
Regimental Commanders are selected from King Kurt's 'inner circle' of relations and loyalists, and so far as we know are 100% loyal.
In battle, one or more Spitfire Regiments will be brigaded in the centre of the army, with conventional foot supporting it, and cavalry on the wings (see footnote). In the early campaigns, the new weapons were screened by foot regiments until the enemy were quite close, then the foot regiments would move aside, and the gatling guns would massacre the enemy centre - the rest of these battles was usually mopping up.
These days, the presence of a Spitfire Regiment is enough to force a conventional army from the field without a fight - so they don't fire all that often now. The main fighting is currently around sieges, in which the gatlings are used mainly in support of storming a breach (but the long process of breaching etc has to be done with conventional cannons etc. It would appear that they tend to conserve ammo by only firing where there are good target opportunities (i.e. against field armies).
The Grand Alliance has tried a number of tactics against the Spitfire Regiment, including:
1. Massed Cavalry Charge with Gendarmerie (heavily armoured cavalry). This cost the Delta Kingdom the bulk of its nobility. It didn't work.
2. Massed Musketry directed at the Spitfire Regiment. Since muskets are outranged by the Gatling, this never even got started.
3. Using Field Defences. This is difficult to arrange in time, and mostly means the defending army gets outflanked or otherwise pulled out of position. It did happen successfully at the battle of Bacale in Jefferson, and the fieldworks did reduce casualties - but in this battle, the superiority of numbers of the Irion forces won the day in any case.
4. Ambushing the Spitfire Regiments on the march. It has been tried on three occasions, none of which have been successful. The Spitfire Regiments have their own light cavalry detachments covering them when on the march, and their integral infantry protect the guns with fanatical (almost religious) devotion.
Hope this helps.
Dr Agmars Thinkpiece.
Footnote: Irion cavalry is particularly well disciplined - and was generally regarded as among the best on the continent even before the recent wars).