Attachment & Weapon Mods⌗

It seems like a rather large oversight to make a fairly comprehensive set of firearm rules and not include rules for adding attachments or modding your weapons. It surprisingly took a player at my playtesting group to point this out, which made me realize that I had totally missed it. I mean, no good battle rattle setup is complete without a bunch of heavy gizmos sticking off a rifle, just to weigh down an operator before some rando insurgent guns them down with a burned-out AKM produced in 1959 that has magically ended up being serviced in the modern day.

Humor aside, any respectable firearm rules are going to have attachments included, and I believe they are fairly balanced. Again, like in real life, the biggest issue with more features and gizmos on any rifle is that it weighs more, and in an OSR-based system where weight does matter and is tracked, sure your rifle can be “objectively” better than another rifle, but it weighs more, and that weight could have been used for more armor, first aid, or other utility.

Which I guess also leads into me desiring to refresh on the core principles of the system again before we move on to the attachments.

General Mechanical Overview⌗

1. Ballistic Damage: This is a special damage type reserved for firearms and explosives. When the maximum number is rolled on the damage die, the player may reroll the damage and add it. If they roll the maximum number again, they repeat, ad infinitum.

This mechanic is modified by the firing mode of the weapon. A burst fire weapon expands the range in which the damage die can “explode.” For example, if a 9mm handgun rolls a max of 6 on a 1d6 die, then a burst fire PDW does exploding damage on a 5 and 6 on the 1d6. For fully automatic spray, that expands to 4, 5, and 6.

2. System Shock: In my game system, when a player takes half or more of their maximum Health Points in a single attack, they must make a saving throw to avoid going into System Shock. When in System Shock, they are stunned for 1d4 turns and do not add their Dex to their Armor Class.

3. Armor Class and Damage Resistance: Armor Class functions the same as in D&D and most standard OSR systems—a combination of the ability to avoid getting hit and the protection your armor offers. Damage Resistance, however, is a number by which incoming damage is reduced. So, for example, a Kevlar Vest might be +2 AC followed by DR 2, which negates 2 points of incoming ballistic damage.

4. Weight Slots: My system handles encumbrance by dividing it into weight slots. A standard handgun is 1 weight slot, 3 pistol mags are 1 weight slot, and a rifle is 2-3 weight slots. The number of weight slots is equal to a character’s STR score + CON score.

Attachments⌗

Bonus Types⌗

Each weapon has two distinct bonus types:

• Attack Bonus: Applied to all attacks
• Aim Bonus: Additional bonus when taking a turn to aim

Barrel Attachments (1-2 Weight)⌗

Attachment	Weight	Attack/Aim Bonus	Effect	Notes
Suppressor	1	+0/+0	Reduces noise, 1-3 for Ambush checks	Requires threaded barrel
Muzzle Brake	1	+0/+0	+1 to hit on follow-up shots	Increases noise
Flash Hider	1	+0/+0	-2 to detect shooter at night	Standard on military weapons
Compensator	1	+0/+0	+1 to hit on Spray/burst fire	Increases horizontal spread
Heavy Barrel	2	+0/+0	+2 damage hit on Spray/burst fire	Is Heavy
Bayonet	1	+0/+0	1d6 piercing in melee	Can’t use with most muzzle devices

Grip Attachments (1 Weight)⌗

Attachment	Weight	Attack/Aim Bonus	Effect	Notes
Vertical Grip	1	+1/+0	Better control in close quarters	Common on shorter weapons
Angled Grip	1	+0/+1	Better target transitions	Popular on rifles
Bipod	1	+0/+2	Only when prone/supported	Setup takes 1 action
Hand Stop	1	+1/+0	Better recoil control	Minimal profile

Sighting Enhancement (1 Weight)⌗

Attachment	Weight	Attack/Aim Bonus	Effect	Notes
Red Dot Magnifier	1	+0/+2	Enhances red dot at range	Can be flipped to side
Laser Sight	1	+1/+0	Works in darkness	Visible to enemies
IR Laser	1	+1/+1	Can be see with Night Vision	Best used with NODs/NVGs

Additional Attachments (1 Weight)⌗

Attachment	Weight	Attack/Aim Bonus	Effect	Notes
Weapon Light	1	+1/+0	30ft cone, no darkness penalty	Reveals position
Shell Catcher	1	+0/+0	Catches ejected brass	Useful for stealth

Additional Notes⌗

• The Suppressor gives a higher chance of surprise on an Ambush Check, but this applies to the target being shot at from ambush. As well this stacks with subsonic ammo, so a Silencer + Subsonic Ammo is a 1-4 out of 6 on an Ambush Check.

Duplex and Double-Barreled Weapons⌗

Duplex Round Weapons⌗

Duplex ammunition contains two bullets in a single cartridge, fired in rapid succession. These specialized rounds were developed for military use to increase hit probability. Ultimately they were abandoned as a concept due to the vast cost for lack of meaningful increase in effectiveness.

Duplex Round Rules⌗

• On a successful hit, roll two damage dice and take the higher result
• Cannot be used with suppressors or subsonic ammunition.
• Required specialized weapons often to fire this ammo type.

Example Duplex Rounds⌗

• 5.56mm M198 (Two 35-grain bullets)
• 9mm S&B Duplex (Two 55-grain bullets)

Double-Barreled Weapons⌗

Double-Barreled Rifles and Handguns⌗

These weapons feature two separate barrels that fire standard cartridges.

Rules⌗

• On a successful hit, roll two damage dice and take the higher result
• Both barrels fire simultaneously at the same target
• +1 weight slot compared to single-barrel variants
• Cannot mount certain barrel attachments (suppressors, muzzle brakes)
• Increased cost and maintenance requirements

Examples⌗

• Arsenal AF2011 Double 1911 (.45 ACP)
• Heym Express Double Rifle (.375 H&H)
• Savage Model 94 (.357 Magnum)

Double-Barreled Shotguns⌗

A quick refresher on double barreled shotguns, I had these weapons listed before but wanted to bring them up as to avoid confusion as they operate differently than other double-barreled weapons

Rules⌗

• Can fire both barrels as:
  1. Two separate attacks against different targets
  2. Single attack against one target (4d4 damage)
• No penalty for splitting attacks between targets
• Different ammunition types can be loaded in each barrel
• Requires full reload action to load both barrels.

Examples⌗

• Stoeger Coach Gun (Side-by-Side)
• Browning Citori (Over/Under)
• Stevens 311 (Side-by-Side)

Weight and Attachments⌗

• Double-barreled weapons use +1 weight slot
• Limited attachment options due to dual barrel configuration
• Can still mount stock and grip attachments normally

Ammunition Types⌗

• Each barrel can be loaded with different ammunition types
• Track ammunition for each barrel separately
• Special ammunition effects (hollow point, slug, etc.) apply per barrel

Ideas In The Pipeline⌗

Probably the next Firearms related articles are going to be future weapons, such as Gyrojet and airburst weapons, including more crazy sci-fi stuff like laser weapons or plasma or mazer emitter type weapons. Finally I want to make an omnibus article with all the Firearms rules in one place with the presentation cleaned up a couple things tweaked across the rules.