How fast must it shoot to be a supermachinegun?, Whats the cut-off? Options

[HullBreach]

First let me begin by apologizing for my long abscence! I got a little obsessed with some other hobbies for a while and neglected my website, which you can expect to see updated and refreshed with some new content over the next few weeks!

Well, to the matter at hand:

The average fully automatic weapon has a cyclic rate in the neighborhood of 750 rounds per minute. The MAC-11 has a rate of fire of nearly 1600 rounds per minute. I feel that the MAC-11 should be considered a supermachinegun (as outlined in arsenal) but feel its important to quantify a "cut-off" cyclic rate for what is and isn't a supermachinegun.

My gut is telling me somewhere in the neighborhood of 1100-1200rpm should be the cut-off, but Im curious to here what some other folks have to say!

>EDIT: For reference, the MG-42 of WW2 fame had a cyclic rate of around 1200rpm. The M-249 SAW used today is at about 750 (though there is conflicting data on this).

[Malicant]

Link

This can be considered a supermashinegun. Everything below is just not super enough (IMG:style_emoticons/default/biggrin.gif)

[Fix-it]

I'd just make it an even 1000.

[Daier Mune]

since no guns are actualy given a maximum rate of fire in shadowrun, its very hard to tell. assuming that initiative passes are ~3 seconds, and the most you can fire is a 20 suppresive burst, any full auto gun fires at 400 rounds a minute.

[LintMan]

Just a note on machinegun firing speed. The MG42 did have 1200 rpm. However it did not fire constantly at that speed due to two big reasons:

-Barrel melting
-Ammo

Just some things to consider when comparing firing speed.

[HullBreach]

Just a note on machinegun firing speed. The MG42 did have 1200 rpm. However it did not fire constantly at that speed due to two big reasons:

-Barrel melting
-Ammo

Just some things to consider when comparing firing speed.

Very familiar with MG operation (Im a former Marine), but yeah, these are things that GM's should be aware of.

I also realize that combat turns are 3 seconds long, but the automatic fire rules do state that they are assuming the user is firing controlled bursts that make up the 'autofire' action.

Im just trying to pin-point a rough number for use when converting real-world weapons.

[Crusher Bob]

Note that the FAMAS makes the 1000rpm cutoff too.

[Ed_209a]

I like 1200 RPM+.

Design wise, there really isn't that much difference between 750 and 1000 RPM. You can float within that range by just changing the weight of the bolt and changing how much gas blows back to operate the action. 1200+ represents a specific attention to high rate of fire.

I think supermachineguns will probably be electric, like the 25mm chaingun on the M2 Bradley AFV, only scaled down.

What I don't like, is that the art for the HVAR shows 2 barrels, like it uses a rotary barrel action. (I photoshopped one out for the pic I use.)

The thing is, IMO, high ROF is usually a waste, unless you are firing _at_ an airborne target, or _from_ an airborne target. Any other setting, you are usually better off with a heavier bullet at lower ROF. For example, a 5.56mm weapon at 850 RPM is usually more useful than a 9mm at 2500 RPM.

That might be below the mechanical resolution of SR4 though.

[HullBreach]

I like 1200 RPM+.

Design wise, there really isn't that much difference between 750 and 1000 RPM. You can float within that range by just changing the weight of the bolt and changing how much gas blows back to operate the action. 1200+ represents a specific attention to high rate of fire.

I think supermachineguns will probably be electric, like the 25mm chaingun on the M2 Bradley AFV, only scaled down.

What I don't like, is that the art for the HVAR shows 2 barrels, like it uses a rotary barrel action. (I photoshopped one out for the pic I use.)

The thing is, IMO, high ROF is usually a waste, unless you are firing _at_ an airborne target, or _from_ an airborne target. Any other setting, you are usually better off with a heavier bullet at lower ROF. For example, a 5.56mm weapon at 850 RPM is usually more useful than a 9mm at 2500 RPM.

That might be below the mechanical resolution of SR4 though.

I agree with your reasoning regarding 1200, and I think thats going to be my cut-off point for furture conversions. I also agree on their being electric, as the lower reciprocating mass in such a design (simply a solnoid driven firing pin, if even that) makes sense for such a design.

One of my players made a really good point about that second barrel on the HVAR, and I liked his reasoning. Given that that weapon was designed from the ground up to be smart and fast firing, he reasoned that the second barrel is probobly used like the spare barrels we carry for LMG's in the millitary. In other words, once an onboard thermocouple senses the first barrel reaching a certain tempature, it waits for a breif lull in firing and flips over to the other barrel to give the other one time to cool.

Your spot on regarding the last bit, the only situation I've ever been in where we were taught that volume of fire makes a difference is responding to an ambush. In a situation like that, being able to have a few troops lay down some impressive suppressive fire could be pretty handy.

[Ed_209a]

One of my players made a really good point about that second barrel on the HVAR, and I liked his reasoning. Given that that weapon was designed from the ground up to be smart and fast firing, he reasoned that the second barrel is probably used like the spare barrels we carry for LMG's in the military. In other words, once an onboard thermocouple senses the first barrel reaching a certain temperature, it waits for a brief lull in firing and flips over to the other barrel to give the other one time to cool.

That _is_ interesting. I'm not sure it would be worth the weight of the second barrel in all applications, but it sure would be handy when you do have to fire several mags in a few minutes. I can imagine a prompt in your smartgun display "Temp high. Cold barrel available. Swap Y/N?"

[Daddy's Litt...]

So the answer then is- Faster than a speeding bullet?

[Moon-Hawk]

since no guns are actualy given a maximum rate of fire in shadowrun, its very hard to tell. assuming that initiative passes are ~3 seconds, and the most you can fire is a 20 suppresive burst, any full auto gun fires at 400 rounds a minute.

What? 10 shots in a full-auto burst time 4 passes is 40 shots per turn. 20 turns per minute is 800 rounds a minute.

A supermachine gun (in SR4 terms) fires 12 shots in a full-auto burst, so that's 960 rounds per minute. I could comfortably round 960 to 1000 and make that the cutoff, since other people are saying that's a "standard".

note: *I'm not a gun expert!*

[Malicant]

What? 10 shots in a full-auto burst time 4 passes is 40 shots per turn. 20 turns per minute is 800 rounds a minute.

But if you go into spray-and-pray mode aka. suppressiv fire, your RoF doubles.

[Heath Robinson]

We can calculate the possible minimum rate of fire for a supermachinegun by taking the most extreme case and calculating the number of rounds fired for both cases, which will give us the boundaries for inclusion into the groups.

let P be Initiative passes per combat turn
let T be Combat turn time

P = 4
T = 3

let s be Standard Rounds per pass
let S be Standard rounds per combat turn

s = 10

S = s * P
S = 40

Assume that not all time is utilised

let r be Standard Rounds per second
let R be Standard Rounds per minute

r > S / T
r > 40 / 3

R = r * 60
R > 800

let h be Supermachinegun Rounds per Combat Turn
let g be Supermachinegun Rounds per second
let G be Supermachinegun Rounds per minute

h = 20
H = 80
g > 80 / 3

G = g * 60
G > 1600

r < g
r <= 80 / 3

R < G

let A be Proportion of time occupied by realigning gun on target after a burst

G >= 1600 / (1 - A)

Assume A = .25

G >= 1600 / 0.25
G >= 2133 + 1/3

R < 2133 + 1/3

For this set of assumptions the upper limit of a sixth world standard autofire RPM is 2133 (to 1 DP).

I'm ready to be called an ass.

I forgot that the rules relating to suppressive fire don't change for hypervelocity weapons, so we change the assumption of the value of A, raising it to .5 or .6 which gives room for a standard firearm to fire 80 rounds in a combat turn without becoming a supermachinegun. Eh, you can do that piece of mathematics yourself, right.

[Daier Mune]

What? 10 shots in a full-auto burst time 4 passes is 40 shots per turn. 20 turns per minute is 800 rounds a minute.

A supermachine gun (in SR4 terms) fires 12 shots in a full-auto burst, so that's 960 rounds per minute. I could comfortably round 960 to 1000 and make that the cutoff, since other people are saying that's a "standard".

note: *I'm not a gun expert!*

i was under the impression that a combat turn was a universal constant (3-5 seconds), whereas an initiative pass was a fraction thereof. so someone with 4 IPs could move faster than someone with only 1 IP, all those IPs still take place within the same time frame of 1 combat turn.

[jago668]

Your highest rate of fire is going to come from a rotary barrel machine gun in shadowrun. They do full bursts of 15 rounds, and suppressive fire of 30 rounds per pass. So that maximum that I see is 2,400 rounds per minute. Which is about 600 rounds shy of what a rotary barrel can do real world. So far as I know, linked below.

http://www.dillonaero.com/content/p/9/pid/.../Standard_M134D