Battletech: Special Autocannon Ammunition

Howdy and welcome back to Battletech. Autocannons for the longest time had a bad reputation in Battletech. They are heavy. They deal mostly middling damage aside from the AC-20, which suffers from critically short range. They have ammo which explodes. There are a lot of problems with basic autocannons.  There are several upgraded or fixed versions of Autocannons, such as the Ultra Autocannon, which has a roughly 40% chance of extra damage, or the LBX-Autocannon, which has the ability to fire pellets like a shotgun and with boosted range. The Gauss Rifle is also, in a way, an improved autocannon, dealing more damage out to a longer range compared to the AC/10.

But there is another way that Battletech attempted to fix Autocannons, Special Munitions. There are several types of special ammo, all of which take aim at a different aspect of these weapons and attempt to fix it. They are free in terms of BV (with one or two exceptions) and can be swapped out for any ton of normal ammunition that your mech is carrying, allowing you to mix and match various types of ammo depending on the exact situation you find yourself in. There are a few types and it can be hard to tell what you should be loading and when, so lets go over that. We are covering special Autocannon ammo specifically this week.

Battletech Rifleman. Credit: 40khamslam.

Armor Piercing Ammunition

The first obvious thing that comes to mind when you think of special ammo types for a very big gun, AP ammo comes with a few substantial downsides. It weighs twice as much as normal ammo, so you only get half as many shots for every ton of it. It also is at a +1 to hit penalty, a pretty punishing drawback. What you gain in exchange is the ability to roll to crit your opponent any time you hit them with this ammo type, regardless of whether you broke through the armor or not. This can either do basically nothing or win you a fight instantly, and even if it isn’t winning the fight it is at least degrading your opponent’s mech by popping actuators and weapon systems through the armor. It is easier to get the crit to succeed if you are shooting a bigger autocannon, like an AC/10, compared to a small one like an AC/2. The rules for this ammo type are in Total Warfare.

When you should take this

I usually would recommend not loading up purely with AP ammo. I recommend keeping a ton or two of it in a mech that is carrying other types of ammo, so that if you get an easy shot on an enemy you can threaten to TAC them. Its a good choice for your second or third ton of ammo, but not for your only type of ammo.

Flechette Ammunition

Flechette Ammunition is simple. You do more damage against infantry and less against everything that isn’t infantry. The rules for this ammo type are in Total Warfare.

When you should take this

Whenever you are expecting to fight just a metric fuckload of infantry. Don’t make this your only AC ammo, but a single ton of it on a mech that is expecting to need to kill infantry is not the worse thing in the world.

Centurion. Credit: Rockfish
Centurion. Credit: Rockfish

Flak Ammunition

Coming from Tactical Operations instead of Total Warfare, Flak Ammunition is also very simple. You have an easier time shooting down planes and do less damage to ground targets. Except for infantry, where you deal the same boosted damage as flechette, making this a strictly better version of flechette ammo, near as I can tell from reading the rules for it.

When you should take this

Flak is something you will really want in some games and not want in others. It is a strictly better version of flechette unless I am missing something, so any situation where you would want that, you would be fine taking this. I recommend allowing players to swap ammo types at the start of the game after seeing the opponent’s list, because then you can tailor your ammo loads to the enemy. It’s good to keep a ton or two of this on something with AC/5s or AC/2s if your enemy has some helicopters, it really helps with fishing for Rotor hits and bringing them down.

Tracer Ammunition

Tracer Ammunition is interesting. It lowers the penalty from night fighting at the cost of a single point of damage. This is a good trade off if you are expecting/choosing to fight at night, but the issue is that -1 damage. That is half the output of an AC/2, 20% of an AC/5, and it puts a AC/10 down to 9 damage, which is a massively awkward amount. 9 damage is exactly one point away from forcing a crit check if you hit the head. So, a normal AC/10 round hitting the head still has a chance to instantly kill, but a tracer AC/10 round doesn’t. AC/20s don’t particularly care because 19 damage is in fact still a fuckload of damage, so that is probably the best weapon to use this ammo type on. The rules for this ammo type are in Tactical Operations.

When you should take this

If you are expecting to be night fighting, accuracy is always very nice. I would still maybe not make this your entire ammo load even if you are night fighting, because you might end up with a really easy shot that you would want to do max damage on.

Federated Suns Armored Cavalry Hunchback. Credit: Jack Hunter

Caseless Ammunition

A bit of an odd duck by Special Ammunition standards, caseless ammo has a number of drawbacks. For one, unlike all other types of special munition, if you choose to use caseless ammunition in an autocannon, that autocannon can only use caseless ammunition and cannot swap to another ammo type mid game. This is pretty limiting, as one of the best factors of special munitions is that you can carry a few types and adapt to the situation. In addition, if you roll snake eyes on a shot, you jam the autocannon up and can’t use it for the rest of the game. So what do you gain for all of that downside? You double the ammunition you get per ton, giving an AC/10 20 shots per ton, or an AC/20 10 shots per ton. The rules for this ammo type are in Tactical Operations.

When you should take this

Any time you only have one ton of ammo for each AC/10 or AC/20 this is a great pick up. Doubling the ammo on something like a King Crab, Hunchback, or Enforcer can really help with sustain in fights. If you have more than 1 ton of ammo per gun you would need to be in an incredibly long fight before this would pay off. It is really, really good on a specific handful of mechs and somewhat mediocre on a lot of other ones.

Precision Ammunition

The big cheese, the grand poobah, the supreme patriarch of AC ammo and the reason that I have developed a crippling and incurable addiction to basic AC/10s. The one, the only, Precision Ammunition. For downsides, you only get half as much ammo per ton, so an AC/10 only gets 5 shots per ton instead of 10, for example. That is the only downside, but as for bonuses, it subtracts 2 points from your opponent’s TMM. This translates to a more or less free -2 to hit bonus on any mech that moved at least 5 hexes. Most good, competitive mechs will be trying to move 5 hexes a turn to keep their TMM’s up, so this will pay off nearly constantly. If the opponent stands still to prevent you from gaining the bonus, well, they stood still, so you get to hammer them anyway. Precision ammo is genuinely so good it, in my opinion, makes the basic AC/10 into one of the best weapons in the game from a raw damage ouput to BV ratio standpoint.

When you should take this

Precision ammo should be your default choice whenever you don’t have any better ideas what to load in a mech. Any mech with more than 1 ton of AC ammo should be loading precision. Some mechs with only 1 ton are still better off loading precision. Precision turns your Autocannon into a pulse laser and it is very, very worth it. I adore this ammo type. It makes the big boom bang bang guns actually usable.

Federated Suns Armored Cavalry Victor. Credit: Jack Hunter


Load Precision ammo by default, with AP as the secondary and the other ammo types if you are in a game that will benefit from them. Using special ammo will massively increase the power of any autocannon mechs that you like to use. For dedicated special ammo caddies, I recommend the Enforcer III 6Ma and the Rifleman 6D. They both come dirt, dirt cheap and have good capacity to load up on precision ammo and AP ammo. Hunchbacks also in general really love special ammo, as they are mostly built around Autocannons.