4e Mechanics: Multi-barrel, multi-mount, and high-ROF weapons

[Tegyrius]

Starting a new thread because I have an overdeveloped drive for taxonomy and the existing 4e mechanics thread is becoming rules burgoo.

I started thinking about this a few months ago when I threw a ZSU-23-4 at my PCs. A single 2A7 23mm autocannon has a cyclic rate in excess of 800 rpm. By the 4e conversion rules, that would set it to ROF 6. So far, so good... but adding three more firing in unison, for a nominal ROF upwards of 3,000 rpm, has no additional effect. My hand-wave at the time was to say that the marauders in possession of the Shilka were only firing one of the guns to conserve ammo, but the problem lingered in my head.

The same issue exists for dual and quad MG mounts and rotary cannons. Not that I intend to give my PCs a minigun, but gun trucks with quad-.50s or ZU-23-2s are possible encounters... and I do have an odd appreciation for the LAV-PIVAD.

Urban Operations does feature a [spoiler if you're new to T2k] with a YakB 12.7mm rotary MG. Free League's solution for a gun with a 4,000 to 5,000 rpm cyclic rate was to model it as ROF 8. I have to admit that I find this rather unsatisfying. Two more ammo dice just don't seem to do the concept justice.

Any thoughts?

- C.

RoF 8d12* (with 7 to 11 rolls = to a 6; and a 12 doubling to 6x2). Less jams, more awesomeness!

*IMHO, ammo die for machine-guns should really scale according to millimeters, or something along those lines. 5.56mm 1d6, 7.62mm 1d8, etc.

[Raellus]

It seems to me that if multi-barreled weapons were modeled even close to realistically, they would be game-breaking- pretty much guaranteed suppression and/or rapid break down (every one rolled reduces Reliability); on pushed rolls, super high chance of jams. Maybe that was the design philosophy behind nerf'ing their ROF.

-

If that's the case, then the designers would do well to remember that GDW put the Fusion Gun Man Portable in print for Traveller, along with plenty of other 'game breaking' things, throughout their publication history. Other RPGs publish game breaking gear/items/magical items as well.

Sometimes you have horses and sometimes they have machine guns and that's just how it is.

<gives FL the stink Eye of Vecna>

[Claidheamh]

Because I always loved the Weapon Guides from GDWs days, I've picked up a few of the 3rd party weapons guides published on DTRPG under the FL license. I think the guides by Geir Ove Thorsveen are the best and most consistently written ones. He has added some nice optional rules covering ROF and bracing weapons, as well as concealability and other gaps in the FL rules.

His GPMG / HMG supplement has the M134 Minigun with an ROF of 10 and different barrel options for the KPV machinegun (ZPU-1, ZPU-2, ZPU-4). Basically, if the KPV has an ROF 4, the ZPU-2 (2 barrel) is ROF 7, the 4 barrel is ROF 10. Not a perfect solution, but pretty workable.

(https://www.drivethrurpg.com/product...-North-America)

[Rolando]

maybe multiplying the number of barrels means multiplying the succeses... a 3 barreled gun rolling a 6 counts as 3 extra 6's. A 1 stills counts as a single 1 because these weapons are made to be fired at full auto.


This would be my simple "I don't want to think much about it" solution.

[Higgipedia]

Originally Posted by Raellus

It seems to me that if multi-barreled weapons were modeled even close to realistically, they would be game-breaking- pretty much guaranteed suppression and/or rapid break down (every one rolled reduces Reliability); on pushed rolls, super high chance of jams. Maybe that was the design philosophy behind nerf'ing their ROF.

-

Our HUMINT team had a minigun on their truck in Iraq. It was a beast to keep running smoothly even with good logistics. When it was up and running, it was a suppressive fire monster, so that modeling tracks.

[Heffe]

I've probably been overthinking about this a bit, but this is where I've currently landed to best abstract an attack with a multi-barreled weapon system:

The current 4e skills and dice rolls, including ammo rolls to an extent, all represent a "to-hit" chance. While higher ROF weapons put more lead downrange, their ability to actually hit their target still depends upon the initial skill dice roll (the base dice); the ammo dice rolls conferred from high ROF just adds suppression, or additional hits in the event of a hit from the skill dice. In short, ROF doesn't actually matter if you don't "hit" the target you're shooting at outside of suppression likelihood, and I'm not sure that would actually change a whole lot at the high ROFs you'd normally find on a multi-barreled weapon system. Thus, ROF and their resultant ammo dice are a system with diminishing returns. Let's use some examples to illustrate what I mean:

M82A1
ROF 1
Maximum number of targets that can be hit in one hex (max targets): 2
Maximum damage possible on a single target (max dmg): 5

M4
ROF 3
Max targets: 4
Max dmg: 2+3

M249
ROF 6
Max targets: 7
Max dmg: 8

Using the same comparison chart, the M134 minigun mentioned above would yield:

M134
ROF 10
Max targets: 11
Max dmg: whatever the base damage is plus 10.

What I mean is this - it doesn't matter what your rate of fire is if you aren't hitting the target with your base die roll, at best it will only increase the likelihood of the target being suppressed.

What I'm further driving at is that even with a four barreled system like quad-.50s or the ZSU-23-4, if all you're doing is increasing the ROF, then you're really just increasing the number of targets that can be hit in the same hex or the amount of damage being conferred by a hit based on ammo dice successes. Given that the number of available targets in a given hex usually won't even be enough to warrant raising the "max targets" parameter, and the "max dmg" being done by multiple successes only scales so much, I'd propose a different approach for multi-barrel systems:

Use the base dice to determine whether or not the hit on a target(s) succeeds, but calculate the targets hit, damage done, and armor modifier of each barrel separately when determining damage.

For examples, say you fire a quad .50 at a group of six soldiers in a given hex. The firer rolls their base dice and max ammo dice, and hits with the base dice and 2 of the ammo dice. The base dice hit would result in 16 damage (with 0 armor modifier) to the core target, or a hit on four separate targets in the hex, or 8 to one target and 4 each to 2 other targets. The firer would then divy up the 2 additional points of ammo dice damage as they see fit in accordance with the normal rules.

As a separate example, say the target is a BTR but everything else is the same. All four barrels would hit the BTR, but none of them would penetrate except for the 2 hits from the ammo dice (each barrel does 4 base damage with no armor modifier and the BTR has an armor level of 4). In other words, instead of doing 18 damage, the most penetrating damage that could be done would be 6.

As a final example, say the target is a single, poor infantryman, and everything else is the same. The hit would do 4 x4 barrels worth of damage, +2 from the ammo dice damage, or 18 damage in total. If the infantryman was wearing a flak jacket, it would only do 14 damage in total (3 x4 barrels worth of damage, +2 from the ammo dice damage).

[leonpoi]

The centrefire series does just up the ROF - I would probably do that out of simplicity.