I am writing up a post apocalyptic hack for ICRPG and have a gun table. Much of it directly inspired by ghost mountain (see that section in master edition for lots more flavor on guns) and altered state. I have leaned into use of HARD/EASY NEAR/FAR, and scarcity of bullets. Guns in my setting are scary and rare, so they are meant to pack a punch.
Pseudorealistic Selective-Fire Gunplay for ICRPG: Two Approaches
Kotzsu
#8
Thanks! I’m not totally sure one big item taking up more than one inventory space gels with ICRPG. Not a lot of examples of that in existing ICRPG items, I don’t think. If it becomes too fiddly, we’ll drop it.
But so far my players grokked the idea, and “big-guns-take-more-space” seems like a good trade off to me.
Excited for your apocalyptic hack! It looks awesome!
KaneDriscol
#9
I find that multiple inventory slots is a great lever to pull on when creating loot. The Iron Shield and the Great Sword take up multiple slots of inventory (2 and 3 slots respectively). You can also go the other way like the Travelers garb and grant extra inventory slots too.
N99
#10
Thank you for posting your thoughts on this- wonderful stuff. I’m from North America as well and I also like guns 
I’ll look more carefully into trying out/testing your alternatives to gun effort, etc. I’ve been working on some World War II-based historical and alternate history scenarios for ICRPG and your posts definitely caught my attention.
chrisbynum
#11
I finally downloaded Bearcats today. It’s certainly an innovative and impressive tour de force; it is also quite a righteous homage to its cinematic inspiration, something our fearless leader should be very proud of overall.
Looking specifically at the gun rules to which I was directed, I see that the ballistic mechanics for several classes of more-or-less conventional firearms are included. Examining them as examples one by one, we have…
- Thumper Pistol: 5 round cap. 1D6 damage single shot, knockback on any hit.—This is your classic large-caliber handgun with limited capacity and plenty of stopping power. Think Dirty Harry’s magnum revolver, something “that’ll blow your head clean off.” It does damage equivalent to a standard WEAPON attack in the ME rules, averaging 3.5 points per hit. Except for its special displacement effect (“knockback”), it’s the same as any single-projectile double-action handgun proposed in the OP.
- Mac17: D20 rounds fired on hit, 1 damage per round, roll again if nat 20, empty mag on any 40+ burst—This gun represents any number of mayhem-inducing “spray ‘n’ pray” compact full-auto pistol- or carbine-caliber firearms: MAC-10s, Uzi pistols, Nazi MP-40s, M3 grease guns, stocked VP70zs, or (my personal favorite) the oh-so-futuristic P90 PDW. All are high-capacity, high-rate-of-fire, moderate-power, shock-and-awe small arms that excel at close-in fighting. Sending enough lead down range is job #1; maybe they all hit, maybe they don’t… Presumably the effort reduction down to one point of damage per round here is a mechanical reflection of the more moderate muzzle energy of these calibers in combination with the lower hit probability of wild, full-auto fire from short barrels, since mechanically the burst of 1 to 40 rounds either “mostly” hits or completely misses. This makes for an average damage per successful attack of about 11 points with these personal defense weapons, with a decent chance for heavy damage into the 20- to 40-point range—which seems very “swing-y” (as might be appropriate). The mechanics as stated also assume an ample supply of ammo and seem to grant reloading as an implicit free action, only running dry after delivering a maxed-out attack; this might work better for some settings than for others. The Bearcats implementation for this class of firearms seems to have the most different in-game feel from similar guns under the rules I proposed above, where even a long burst with perfect aim from a full-auto weapon (10 rounds is the maximum practical burst size versus unarmored opponents), will deliver just 25 points maximum damage (the chance of this is well under 1%) unless a critical hit is rolled (for 37 points theoretical max), and about 10 points total is the expected average on an unarmored opponent under favorable conditions—still enough to kill the average human with a single attack action, as is appropriate with automatic weapons. Weapon capacity/reloading is respected under my scheme, and so it becomes an aspect of the firearms combat for a different kind of feel.
- Mag22: 1D4 rounds fired on hit, 1D6 damage per round, mag only empty on a crit fail —This gun is the generic, middle-of-the-road selective-fire small arms weapon, moderate in power, rate of fire, and capacity. Think of certain models of the US Army’s acclaimed M4 carbine (based on Stoner’s AR15) as an example. Bursts of one to four rounds in an intermediate-strength caliber yield appreciable damage per attack (almost 9 points average), and the magazine capacity is ample (with presumed access to spares) but not bottomless under the specified mechanics. This implementation from Bearcats provides very much the same reliable expectation and feel as a similar firearm under my proposal (which would yield better than 8 points average damage per successful attack using three-shot bursts), save for the need to pay attention to the ammo supply and spend actions to reload after running dry.
- Sniper: 1 mile range, single target, if hit, target must ‘save or die,’ 2 round reload—This entry seems to encompass all manner of scoped “precision rifles”, from a bolt-action deer gun or M24 sniper to a magazine-fed semi-auto like the SVD. Low magazine capacity and unerring long-range accuracy are the hallmarks of the class. Personally, I’m not a big fan of the save-or-die “head-a-splode” mechanic or the play experience it engenders in the game, but it certainly is dramatic. Same thing with range having no effect (although this kind of gun can certainly cover the scale distances on most battle mats with relative ease.) The mechanics of this weapon—while clearly perfect for Bearcats (which explicitly states its intended desire for nail-biting peril and hyperrealistic big-hit energy)—reflect the sort of game feel to which I was offering an alternative when I wrote my OP. While this type of gun was not the principal focus of my proposed rules in the OP (as the title of this thread attests), they still totally work with the same simple mechanics; I would probably just say that these slow-fire rifles with high-powered optics can make called shots EASY at any range, and then grant them extreme-range capability and increased chances for critical damage on those targeted hits—perhaps adding bonuses from both INT and DEX to benefit the cold, calculating long-range marksman with sharp eyes, a steady hand, and nerves of steel. I would also take away these benefits when the shooter isn’t stationary during the turn, since this kind of precision shooting is greatly hampered when on the move.
- Scatter Gun: Easy to-hit rolls, 30’ range, hits up to 1D6 targets with 1D6 damage each, never empty—While I didn’t give them much lip service in my OP, defensive shotguns (which I adore) are long guns that fire multiple-projectile rounds from a smooth bore all at the same time with the same hit probability; they differ from full-auto single-projectile rifles and deserve their mechanics to reflect this difference. Shotguns deliver lots of effective close-range firepower with diminishing effects at a distance. This gun is a proxy for all manner of pump-action and semi-auto shotguns with low capacity and plenty of kick as their trade-off for maximum close-range firepower and lightning-fast target acquisition. I would probably opt to allow one or two adjacent targets (within CLOSE distance of each other) to be targeted with D8 (or D4 each) projectiles hitting from a single buckshot round fired, with a single attack roll evaluated against each target’s respective DEF score. The EASY to-hit rolls and limited range are realistic and make good sense. “Never empty” assumes infinite ammo (very cinematic!) but works for guns with on-board magazine tubes you can top up on the fly (maybe with a DEX check?). That said, the “alley broom” feel of up to D6 targets “in the zone” is a mechanic that feels very “A-Team” to me (because it’s hard to hit six guys at ten yards with just nine pellets of 00 buckshot…), but I bet it’s fun to play! (See footnote below.)
As I mentioned, Bearcats explicitly declares its own over-the-top action cinema thematic goals (“Statting Guns,” p. 25):
“The guns in BEARCATS are futuristic, so let the[m] be badass! I have my MAC17 firing 1D20 rounds per hit, and natural 20’s exploding for another roll! SO MANY BULLETS. Make your explosives insanely destructive! Work to give every gun its own specific use. They should not overlap.”
The example guns on the list achieve this perfectly; they each have distinctive flavor and weapon-specific mechanics that support them in the game. They seem fun, and they probably work great for the setting and give it an exciting and cohesive feel.
I went with a different approach in the OP because I had different aims and priorities.
First, I wanted to search for workable mechanics that captured sufficient realism without bogging down the game, i.e., no separate to-hit rolls for each round of full-auto fire but reflective of the probability relationships of rounds fired in very quick succession. Magazine capacities were also an important nuance for me to capture, because deciding how many bullets to fire and when to reload were tactical considerations of gunplay I wanted to be sure to include.
Second, rather than defining each and every weapon with a specific set of unique flavoring mechanics, I wanted to define a very short set of universal rules to cover any and all modern firearms and preserve verisimilitude with only a few key gun-specific statistics as input data: firing action, magazine capacity, and effective range.
With these mechanics in place, entries like…
- Magnum revolver (double-action 1, capacity 6, NEAR)
- AKM (auto 10, capacity 75, FAR)
- M4 carbine (burst 3, capacity 30, FAR)
- M24 (scoped bolt-action 1, capacity 5, EXTREME)
- Police 870 12ga (scatter pump-action 1, capacity 6, NEAR)
…are all I need—along with a couple of mechanically defined universal weapon tags for flavor (just like melee weapons)—for complete and realistic firearm descriptions, and with a single die roll I know exactly how many rounds hit, how many miss, and how many remain in the gun. The only additional rolls and simple math required are for the damage calculation when multiple rounds hit, and it all makes intuitive sense with respect to the ballistics. (Even these damage calculations could be easily streamlined to a single-roll optional mechanic that still counts rounds, making this style of pseudorealistic full-auto gunplay as fast and smooth as possible, if that is your preference.)
I think all the ideas proffered and referenced by everyone who has posted here have significant merit.
What this exercise has underlined for me is that there is more than one good way to hack this problem. ICRPG presents a bevy of options to handle this type of combat encounter that are easily tailored to support specific styles of play. I think this attribute of built-in support for GM creativity and options during worldbuilding and encounter construction is a clear testament to the brilliant design of the ICRPG system; it is a truly universal gamemaster’s toolkit.
All of you who have had a hand in creating, defining, and refining ICRPG by contributing over the last several years have something to be proud of, and I am grateful to enjoy the benefits of the groundwork you’ve laid.
Notes:
The accepted rule of thumb among shotgun aficionados, hunters, and LEOs is that standard 9-pellet 00 buckshot fired from the smooth (uncooked) cylinder bore of a typical 18.5” barrel general-purpose pump-action shotgun will exhibit a pattern spread at a rate of approximately 1” per yard of range. Therefore, at ten yards (30 feet, or within NEAR distance), that pattern will place 9 pellets of buckshot in the space of a dinner plate—ten inches across, not ten feet. You might be able to feather that pattern between two bad guys standing right next to each other to hit both with a couple of pellets, but hitting three to six guys dispersed at that range tends to break immersion for me, especially when striving to flavor the mechanics with a little bit of real-world ballistics.
Khan
#14
I think it is not about typing, it is overthinking. It is great if you are launching a telescope into orbit, but for a game, this looks too much.
By the way, I did read everything you wrote. Overall, I agree with your thinking but I disagree with devoting this much time and energy into what most would call minutia. I am not undervaluing the value of thinking and intelligence and if a game is that important to you, then who are we to judge?
Americans and their guns… 
The_Merlitron
#15
I’m American, and I don’t like guns in reality, but guns in RPGs are fun!
I haven’t read every word written, but I love one line descriptions to sell the difference of one gun from another -it’s great! Keep thinking big thoughts, and including fun things in games! I’m loving all this stuff
Rock on, you crazy gun bunnies!
Looten
#16
Honestly, even though it’s a lot, it covers just about every issue and topic that comes up when it comes to figuring out gun play in games. So now instead of sending people a bunch of different links I can point them to this single, all inclusive tome. Sometimes you really need to hit the nail to keep it in the coffin. There might be a better way to sum it up, but this kills a lot of "yeah, but"s on arrival.
chrisbynum
#18
UPDATE: Playtesting of these proposed alternative gunplay mechanics has continued to go quite well at my table in a variety of homebrew one-shots, using the simple one-line clasfication for virtually all firearms (defining action type/rate of fire, ammo capacity, and effective range) in combination with the following global gunplay refinements:
- The single-roll “damage cascade” technique* for decrementing the GUN effort done on successive hits—so three hits with an effort roll of 6 does 6+5+4=15 total damage—works quite fast to keep the turns moving.
- I have been using the additional rule for long ranges applied to any weapon that does GUN effort: shots that exceed the weapon’s effective range by one category are HARD, and shots that exceed the effective range by two categories only hit on a natural 20, so a handgun (NEAR effective range) can hit a FAR target on a HARD DEX roll but will only hit a DOUBLE FAR target on an unmodified roll of 20.
- Magnified weapon optics, AKA “scopes”, eliminate HARD rolls for firearms, so a scoped pistol hits on normal rolls out to FAR range but still requires a natural 20 to hit a DOUBLE FAR target; called shots are still HARD (in contrast to my original suggestion), and the benefits of scopes are lost if the shooter is on the move.
- Nonmagnified (1x) illuminated “red dot” optics, which CAN be used on the move, make shots within effective range EASY rather than eliminating the extended range penalty (although the shot must be sighted, not a point shot); inventory space permitting, a red dot optic can be combined with a magnifier on any long gun.
- EXTREME range (anything beyond four bananas) is always at the GM’s discretion, depending upon the configuration of the firearm in question.
* FOOTNOTE
Game design geeks with slide rules will note that the damage cascade also makes bursts of full-auto gunfire slightly more “swing-y” in terms of effort by linking the individual hits and making subsequent ones derivative of the first; this means if you roll high damage, all the hits are high, and if you roll low, all the damage is minimal. The original method of rolling and decrementing each hit is probabilistically independent and decremented only by order in the burst, so the base rolls tend toward the the average.
The Blackwood File (Cosmic Horror) @ RuneJammer 2023
Can Index Card RPG do Sin City?
rpgerminator
#19
What happens if you roll a 1 or 2 for EFFORT? Would it be: 2/1/0 and 1/0/0? Or would you carry over some 1’s? 2/1/1 1/1/1?
chrisbynum
#20
Excellent question. 
Damage effort of 1 is always the net minimum for a successful bullet strike.
Three strikes on an effort roll of 2 becomes 2+1+1=4 points total damage.
Also, I apply GUN effort bonuses to the aggregated total damage of the entire burst, not to each individual bullet strike. (This may seem obvious from a game design perspective, but I put it in writing here anyway.)
chrisbynum
#21
MECHANIC REVISION: SCATTER
After regularly implementing the “damage cascade” revision for full-auto firearms in my game, a minor concern that arose for me after further playtesting these homebrew rules for pseudorealistic gunplay regarding shotguns and other firearms shooting multiple projectiles from a single round, i.e., those using ammunition like 00 buckshot shells with the “scatter” tag.
Shotguns had become a bit overpowered counting each pellet that hit (based on an additional D8 roll after a the initial successful D20 DEX check) as an independent strike doing GUN effort, averaging a hyperlethal 20-point blast when fired. While this definitely captured the feel of the devastating power of buckshot at close range, it set shotgun wounds very low on the survivability curve compared to those from a three-shot or five-shot burst from a submachine gun or assault rifle, which average 11 and 13 points respectively, where each hit represents an actual bullet, frequently of greater mass than a buckshot pellet and sometimes also traveling at higher velocity. (Example, a 9x19mm “+P” SMG round is nearly three times the mass of a single 00 pellet of “low-recoil” police buckshot, and both travel approximately the same speed when fired from archetypal weapons that use them.)
This in-game power discrepancy between shotguns and automatic weapons was made even more concrete by the convergent effects of the probability distributions associated with the mechanics in use. Average damage for scatterguns was focused and centered very reliably around 20 points of damage, owing to the bell curve yielded by multiple D8 rolls, while the full-auto burst was governed by a single, substantially more “swing-y” D8 damage roll a used for all of the individual strikes in a burst before the damage cascade decrement was applied, tying all of the bullets together in their aggregated damage output, sometimes very high and sometimes very low.
I tweaked the rule for shotguns using “scatter” ammo like buckshot, so that instead of each independent strike from a typical 9-pellet load dealing GUN effort, now only the first one does, similar to the damage cascade implemented for full-auto guns. Every additional shotgun pellet of the remaining eight that hits on a subsequent D8 roll adds a single point of extra damage, parallel and equivalent to the 1-point minimum for all full-auto strikes.
Effectively, shotguns firing buckshot now deal DOUBLE GUN effort, averaging 9 points of damage per blast instead of 20–still enough to kill a one-heart target almost half of the time with a single shot, but ranking them just behind SMGs and assault rifles firing full-auto or multishot bursts, which feels more realistic and provides for more expedient, more dramatic, and more satisfying ballistic combat in the game when the bullets (and pellets) start flying…
(Theoretical maximum damage also has a more realistic cap. A lucky max damage burst of five shots from an SMG (only a small fraction of one percent likely) can do 30 points of damage before any GUN bonus. Conversely, a max damage shotgun blast (significantly more likely with an approximate 1.5% chance) deals 16 points before any bonus—down from a vanishingly small chance of the former theoretical maximum of 64!)
Shotguns under this amended rule for damage output remain highly lethal, very effective for characters, and smooth to run at the table.
Iskander
#22
Interesting discussion on the modelling of gunplay with ICRPG. One thing I’m missing though is what is the goal of these rules?
By this I mean, what kind of play/story are these rules supposed to support? Which stories actually involve realistic usage of guns? A battlefield? Hunting? Drug cartels? Police action? It seems to me that with realistic simulation of guns they are so lethal that they would be mostly used for intimidation rather than actual use for any significant fraction of play time, so really gun rules used for RPGs are usually not very realistic, but I’m curious about your intent and thoughts.
chrisbynum
#23
All of the above. 
In truth, this current set of homebrew firearms rules Supports and facilitates every one of the hypothetical scenarios you listed.
I use them mostly for cosmic horror games and post-apocalyptic scenarios, but I also use them for a variety of modern one-shots and WWII-era commando-style adventures.
The goal is to keep firearms practical to play at the table but more believable in terms of (some of) their in-game effects, as an alternative to treating individual (types of guns) like magical spells, with proprietary rules, gonzo effects, and unrealistic modes of application that shatter player (and GM) immersion in grittier, more grounded adventure scenarios.
I am specifically selective in simulating aspects of gunplay. I want the most likely outcome from getting hit by a shotgun blast or a burst from an SMG to be death for a typical human, but I balance that lethality by counting bullets in favor of endless supplies of ammunition, and governing hit probabilities (largely) in line with the way things work in the real world. In practice, this adds some very interesting dimensions to the game, offering some drama and meaning to player choices round by round.
There is a time, a place, and a setting for “I see the six bad guys, and I mow them all down with my shotgun.”
These gun rules are for all the other times.
