Field Guns and Field Artillery
These are vehicle-scale weapons in a form which can be manually-operated by infantry units to a greater or lesser extent.
Field Guns and Field Artillery differ mainly in how they are meant to be employed; field guns are direct-fired, while field-artillery may be direct-fired at nearby targets, but are mainly meant for “Indirect” employment against targets more than one map away.
Units equipped with these kinds of weapons are effectively immobile if they are not provided with transportation in some way. These may be from units equipped with mechanized or motorized capabilities, or larger vehicles capable of towing the weapons at-issue and transporting the crews.
At their simplest; Field Guns and artillery are larger ballistic and artillery weapons (Not things like machineguns, in other words) able to be operated and handled in the field by infantry soldiers. These soldiers may be equipped with other weapon types (and they should be!), but manning the big guns requires (at heart), one unit member, per ton of weapon. Field Gun and Field Artillery units are considered “Special Infantry” and thus have a normal infantry skill and their “Big Guns” skill.
So, an AC/5 Field Gun requires a basic crew of eight members. This crew receives a bonus ton of ammunition (20 shots in this case; special ammo bay limits do not apply, but caseless bonuses do).
A Thumper Field Artillery Piece needs a crew of 15 to function. Almost twice what the AC/5 does. They still get the basic ton-allotment of ammunition as well; another 20 shots in this case.
Artillery “Cannon” count as field guns for our purposes.
As-is, neither is mobile on the tabletop. Both have the ability for their crews to chose to man the gun or fight as infantry. They can even have extra crew members (if they have them), fight as infantry, simultaneously to firing the gun. Even if they are heavy or support weapons operators, and even if they do not have enough spare crew. An exception to the crew-served weapons rules above that applies only to field guns and field artillery. Field gun and field artillery crews may also engage in hand-to-hand defence, as normal infantry, but lose the ability to fire the gun on the turn they do, unless they have already fired.
Both can vary their ammo-load by the shot, whereas another unit like a mech or tank would need to do it by the ammo-lot. So, the Thumper might have ten-rounds of High Explosive (The standard artillery ammunition), five of smoke, four of incendiary and one copperhead round. The only difference between the two crews at this point is that the range for the Thumper is in Maps and the range for the AC/5 is in hexes. The normal rules for direct-fire of artillery still apply here.
Additional ammo may be dropped, or may have been dropped by supporting units on the gun position and this may be used and must be accounted for as well, but absent vehicles; it cannot be moved, in-game. Units that can move can take the basic single-ton-equivalent lot with them, so long as they have it, but can only load one additional ton per turn and only take as much as they have cargo space for. The rest must be abandoned when they move off the gun position.
In both cases, these weapons are dedicated field guns/field artillery. The AC/5 does not really weigh 8 tons, nor the Thumper fifteen. Capturing either gun, gets you a field gun or artillery, not a weapon you can slap in to replace a weapon on a vehicle. However, you can use them to repair damaged vehicle weapons. Instead; much of the mass and equipment is missing or modified to be replaced or operated by the gun crew.
Unlike other “Infantry” types, Field Guns and Field Artillery do have a “Facing” that need to be considered and can only change it by one hex-side a turn. In-action, the facing gives an arc of fire like a fixed (non-turreted) vehicle weapon. This does not apply to the unit’s infantry weaponry, however.
A single gun and crew may be a unit on their own. They are handled, otherwise as immobile infantry. They can and maybe should have extra members; if they lose a crew-member, they lose the ability to fire the gun every turn. At up to 50% casualties in the gun crew, this means firing the gun that is their purpose every-other turn. From 49-25%, it’s every 3rd turn and below 25%, the gun is effectively inoperative. So extra crew-members in the unit can be very useful. They can do more than act as ablative armour, however; although no amount of extra crew-member can make the gun shoot faster than once a turn.
Field guns and artillery can be made “Auxiliary”-propelled, granting the unit a movement of 1, but this requires an extra crew-member for every 10 tons of mass of the weapon in question, increases cost by 30% and the tech base/complexity/availability by one step. Auxiliary-propelled Field Guns and Artillery can change facings by up to two hex-sides a turn, but weigh 20% more for every ten tons of the base weapon for towing purposes.
If it matters; the engines powering Aux-propelled guns and artillery are very small, just powerful enough to manage a modest hill or help drag the gun up a big one. They often require fuel and when they do; the tank is very small and they aren’t always meant to be run all the time. In-position, they usually run on batteries or act as generators themselves. The effective driving range is typically between 50 and 100km under normal conditions.
Auxiliary-propelled guns move as small wheeled vehicles up to 15 tons of mass of the original gun; allowing them to move through light woods and similar terrain. Above 15 tons, they are treated as wheeled vehicles for movement purposes.
Normally, Field Guns and Artillery are incapable of engaging airborne targets; they simply aren’t made for it, they are not as responsive as the weapons mounted on mechs and vehicles. But for the cost of an additional crew-member per five-tons (round) of what the gun would weigh if it were a mech or vehicle-weapon, a given field gun or artillery can be fielded as a “Dual-threat” gun, capable of engaging air and ground targets.
Such weapons count as heavier for towing purposes at the rate of 20%, but they also return to not needing set facings like more common infantry. Cost, however increases by 50% over the base weapon and complexity/tech-base by one and availability by two-steps. Field Guns and artillery can be had as auxiliary-propelled dual-threat guns as well, but this is rare as the additional cost (+75% total) makes their acquisition often uneconomical. They are also more complex at two steps, require higher technology (one step) and much less common (three steps). For towing purposes, they are 50% heavier than they would be as normal field guns.
A much more easily realized use for that extra crew member is additional ammunition. Additional crew members allocated for this purpose provide an extra 20% more ammunition, above the basic ton, each. However, they may not be assigned as Support Weapon or Heavy Weapon Gunners. These crew members bring this extra ammo with them when the gun moves (if it can), so long as the ammo lasts.
Individual guns and crews are normally grouped into gun-sections (for smaller weapons) and firing-platoons (for larger ones). These are in-turn grouped into batteries. Larger organizations for such weapons have names based on their traditions. Individual guns and crews may freely be detached without loss of their “infantry” skill, or their “Artillery” skill. What they cannot do is benefit from the dispersed deployment posture of normal infantry.
They also lose the infantry bonus penalties for detection and hiding and have only a +1 un-modified to-hit.
Gun-Crews who have shamefully abandoned their weapons or lost them in action, are treated in all ways as normal infantry, including dispersion, detachment and returning to their +2 to-hit penalty.
The gun, itself is handled through game-balance in a counter-intuitive manner. Normally in BattleTech, what feels right here is a chance to damage or destroy the gun, through luck or a targeted attack.
While you have that chance through a “Critical Hit”, in which case the gun is lost in one fell swoop, normally, the weapon is only removed from action when abandoned, out of ammunition or the crew is taken out. In the latter case, the weapon is always handled for salvage purposes as if it were damaged to 25% and in need of repair, as per a damaged mech of vehicle weapon of the same class.
So, your guns are harder to hit, but also more vulnerable in other ways. Can we do anything about this? Yes; build your guns as gun-trailers and remove the infantry-aspect altogether.
To close off here, we’ll cover an obvious question; can you have Gauss Field Guns?
Yes, you can. But they must be purchased as Auxiliary-Propelled guns. Since the Gauss technology requires a power source, it only makes sense to provide one that can also move this rather expensive asset. The range on the fuel tank would be better, if not a fusion or similar system; 250km. Stats are different though; +35% for cost, but same Tech, availability and complexity as for mech and vehicle-mounted gauss weapons. For towing purposes, Gauss Field guns are 30% heavier. Gauss rifles become unwieldy in the extreme as dual-threat guns (+60%) and their cost is uneconomic (double), they are two steps more complex and three steps less common.
