A Mighty Fortress Gunpowder Rules

There are some nice firearms rules in the Second Edition AD&D supplement HR4 A Mighty Fortress (see pages 60 and 61).

Here is a summary, for ease of use. Check out the book though, if you have a chance. There are lots of interesting elements contained within.

  • Target AC ignores armor (i.e., using newer terminology, is a ranged touch attack); thus, defense against firearms comes from cover and dexterity.
  • Exploding damage dice on rolls of 8, 10, and 12 without limit.
  • Misfire on a roll of 1 (requires 10 rounds to clean).
  • Hanging fire on a roll of 2; this means the shot does not go off, and the fumble range is increased by 1 on subsequent shots until the firearm is cleaned (e.g., after hanging fire once, a misfire happens on a roll of 1 or 2 and hanging fire on 3).
  • Fouling (called out as an optional rule): three normal shots count as a hanging shot with regard to misfire and hanging fire chances (to represent the accumulating burned powder.
  • Point blank attacks (within 5 feet) inflict +1 burn damage.
  • Matchlock firearms: caliver (1d8), arquebus (1d10), musket with rest (1d12).
  • Snaplock & flintlock firearms:  pistol (1d8), musket (1d12).
  • Wheellock pistols: belt pistol (1d8), horse pistol (1d10).

In the past, I have often just treated firearms like crossbows (that are easier to conceal but make more noise). The HR4 rules suggestions seem reasonable, though, and not overly cumbersome.

    13 thoughts on “A Mighty Fortress Gunpowder Rules

    1. Trey

      I haven’t looked at those for a while, but they are pretty good. I’m not particularly enamored of exploding dice, though.

      1. Brendan

        Myself, I can take or leave exploding damage dice. These rules would probably work okay even without the exploding dice (the ability to ignore armor traded off against the misfire etc chances is probably interesting enough). Just curious, what don’t you like about exploding dice? The fact that a high-level PC can be taken out by a lucky gunshot?

    2. -C

      I like the exploding dice (they raise the average roll by 1), but those dice are so large.

      I’d change the d8’s to 2d4’s, the d10’s to 2d6’s and the d 12’s to 2d8’s.

      1. Brendan

        Or maybe d6, d8, and d10 with exploding numbers of 6, 8, and 10 if you want smaller numbers.

        Even d4, d6, and d8 would work with exploding numbers of 4, 6, and 8. This would probably mesh best with a B/X game (and correspond to magic-user, cleric, and fighter hit dice). Hey, it would even work with damage by hit dice! So fighters would have a much higher chance of exploding the die than other classes. Hmm, I like it.

    3. DrBargle

      I don’t like exploding dice for firearms in D&D, as it suggests that a musket shot is more deadly than a solid blow from a sword. If I were to use exploding damage dice (which I don’t dislike in principle – it works fine in WFRP1e, for example), I’d have all damage ‘explode’. Having a high level PC (or high HD monster) killed by a lucky or skillful (new attack roll for the first ‘explosion’, as per WFRP1e?) shot is perfectly fine, but only if they can also be decapitated or impaled in a melee.

      Also, the problem with exploding dice is smaller dice explode more regularly than large dice, which might create a counter-intuitive effect (daggers twice as likely to ‘explode’ than a long sword), depending on what effect you’re trying to achieve.

      1. Brendan

        the problem with exploding dice is smaller dice explode more regularly than large dice

        I believe this objection is handled by the exploding numbers being 8, 10, and 12. So a d8 explodes 1 in 8 times, a d10 explodes 2 in 10 times, and a d12 explodes 3 in 12 times.

        I agree about the possibility of a sword (or even dagger) also inflicting a horrific wound, but perhaps that is better handled by a critical hit or wound system? I think part of the motivation for a system like this is to make firearms feel different in play (and also maybe give them some degree of advantage, as in the real world firearms really are superior most of the time, even at the Elizabethan level of technology).

      2. DrBargle

        Oh, I’d missed the fact that larger dice explode at all the smaller exploding scores, which is an interesting way of doing it.

        The armour bypass effect makes firearms pretty distinctive though, doesn’t it?

        As an aside, I thought those Historical Reference books were an example of very good late TSR-era D&D stuff.

    4. Martin R. Thomas

      As an aside, I thought those Historical Reference books were an example of very good late TSR-era D&D stuff.

      Agreed. Those books were among my favorite 2ED-era stuff. I just picked up the “Crusades” one a few months ago at my LGS – they had it in the used bin for $5.00.

      “The Mighty Fortress” was the first one I ever got as a Christmas gift the year it came out, and I still like to go back and read it from time-to-time. I had always had the thought of making my entire D&D fantasy campaign as an “Age of Reason” era, but it just never seemed to work and I always ended up rolling it back down to baseline D&D with no firearms.

      1. DrBargle

        I got a bunch of them from a bargain bin – but I’ve never spotted the Greek one (Age of Heroes). Probably have to scour eBay for it.


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