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Auto Fire (Volley)

CoC 7e

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#1 Professor

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Posted 26 November 2017 - 09:59 PM

Page 114 

 

"The player declares the number of rounds (bullets) to be fired, which may be any number up to the capacity of the gun before rolling the dice"

 

I want to fire 75 bullets

 

"The number of bullets fired is divided into a series of volleys, with an attack roll made for each volley. A volley is a number of bullets up to or equal to the firer’s Submachine Gun (SMG) or Machine Gun (MG) skill divided by 10 and rounded down."

 

I have SMG 55% so each volley I roll to attack with has 5 bullets in it. 75 bullets fired in 5 volley bursts is 15 attack rolls 

 

But if I have an SMG of 40%, that's 18 attack rolls with volleys of 4 bullets each?

 

It seems I have a greater opportunity to hit with a lower SMG rating. 

 

 




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#2 Celebrim

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Posted 27 November 2017 - 12:23 AM

First, regardless of what the rules say, I don't think you should allow a volley of 75 bullets.  Not only are there few weapons that hold that much ammo, and those that do are very unwieldy, but I think 75 bullets/round exceeds the cyclic rate of just about any weapon you could possibly be firing for any reasonable assessment of how long a 'round' is.   I tend to treat rounds as 'about a second', which means cyclic rates of 6-12 are fairly reasonable as caps on volley size.   Even if you think a round is 3 or 4 seconds, only something like a MG-42 has a cyclic rate fast enough to put out that much fire in a round.   Besides, that's like 14 pounds of ammunition you just shot off.

 

Second, the rules of every edition have always had trouble dealing with fully automatic weapons because CoC doesn't do particularly well with realism and that works right up until it tries to figure what to do with automatic weapons, when suddenly, for reasons it wants to track every individual bullet you fire.  If you want any sort of realism, you'll probably need to go hunting for a supplement or house rule things yourself.



#3 Professor

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Posted 27 November 2017 - 08:32 AM

It seems to me the autofire rules are cumbersome and don't really work well to the extent they need errata.



#4 Gaffer

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Posted 27 November 2017 - 01:21 PM

I have always tracked autofire burst by burst, making one attack roll (modified as required) per burst, then rolling a hits die based on the cyclic rate of the weapon.

 

I certainly don't understand why one's competence with a weapon should have any effect on the number of rounds a weapon can fire per burst, that's a property of the weapon.


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#5 Celebrim

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Posted 27 November 2017 - 02:05 PM

It seems to me the autofire rules are cumbersome and don't really work well to the extent they need errata.

 

I'm still using a somewhat modified version of the 5e rules, namely:

 

For full auto fire: Divide your long guns chance to hit by two, then add 5% to the chance of hitting for each bullet in the burst beyond the first, up to but not exceeding your base chance to hit.  Upon success, roll a dN where N is the number of bullets in the burst to determine the number of hits.   Purists will complain that the more bullets you fire in a burst, the less your chance to hit, rather than the greater, but that's only partially true (the reason that machine guns fire a lot of bullets is to generate a greater chance of at least one hit) and even the notions of things like climb can be considered to be simulated by the fact that with this system the more bullets you fire, the more on average miss the target. 

 

For each weapon, I also list its maximum burst per round based on the weapons cyclic rate - usually 6-10.  It's not perfectly realistic, but it still seems better than what you are using.

 

The alternative approach that I've seen is essentially the reverse, using the normal chance of hitting but reducing the chance of a hit by 5% for each bullet beyond the first in the burst, and then rolling dN to determine the number of bullets that hit.  That's also fine from a realism perspective, but it does have a huge problem with dealing with multiple targets that will force you to adopt additional rules.

 

I only group the bullets into volleys when the player is spraying an area with bullets, and I only allow that when the targets are basically adjacent (otherwise, you should force bursts to target the space between the intended targets as well).  Typically I'll have the player evenly as possible divide the bullets fire among the targets, and then resolve it as separate attacks on each target using the normal rules.



#6 numtini

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Posted 27 November 2017 - 04:15 PM

My GM favors combat-centric pulpy games, so I've had lots of opportunities to study the combat rules in great depth. Sometimes more than I wished!

 

It seems I have a greater opportunity to hit with a lower SMG rating. 

 

You aren't required to break into the maximum number of bullets per volley. It's up to that many. You are generally better firing volleys of an even number because you round down on the number of bullets that hit. Regular success half the bullets hit/Extreme all hit but half impale--in both cases the half is rounded down.

 

However, higher skill is better because each additional volley incurs an additional penalty die.

 

Volley 1: Regular Attack

Volley 2: 1 Penalty Die

Volley 3: 2 Penalty Dice

Volley 4: 2 Penalty Dice, Hard success required

Volley 5: 2 Penalty Dice, Extreme Success Required

Volley 6+: 2 Penalty Dice, Critical Hit Required.

 

Penalty dice are harsher on lower skilled characters, so it's really hard to hit with additional "volleys" as you go down in skill. Some nice folks here did the math in another thread. But for the 40/50 example you use, it goes 40/16/6 or 50/25/12. 

 

I certainly don't understand why one's competence with a weapon should have any effect on the number of rounds a weapon can fire per burst, that's a property of the weapon.

 

Volleys are not bursts. Volleys are how a single long auto-fire is abstracted in game terms. If you empty a 20 round clip, in game terms you're just holding the trigger down and emptying the gun. In game terms, you divide it up into "volleys" because skill determines how many bullets you can put on target before the recoil forces it off target. More skill = more bullets on rolls with fewer penalty dice. Burst fire in the sense of selective fire where the mechanics of the weapon dictate that one trigger pull shoots a set multiple of bullets is at no penalty and is determined by the gun. Burst fire in the sense of someone with good trigger control shooting multiple bursts is in game terms someone shooting full auto but choosing only to fire one volley each round.

And yeah, I'd much rather have simpler rules for this in most "straight" Call of Cthulhu games. On the other hand, for Pulp Cthulhu, this kind of complication seems more in keeping. The "not shooting your whole clip" burst in real world terms, the "selective fire built into the weapon" burst in game terms, and volley in game terms could be better explained because in common English, we tend to think of them as all being the same.


Edited by numtini, 27 November 2017 - 04:18 PM.


#7 Professor

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Posted 27 November 2017 - 04:19 PM

Page 116

 

Let's say the gun has a capacity of 50, you get a success on 40 bullets fired, so rolling for half of shots fired. You roll 20 times?


Edited by Professor, 27 November 2017 - 04:25 PM.


#8 Celebrim

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Posted 27 November 2017 - 04:51 PM

numtini: Ok, that makes a good bit more sense, though it still means characters (whether PCs or NPCs) with high SMG skill are terrifyingly lethal.  

 

In general, I think the fact that SMG's are not nerfed in effectiveness compared with how heavily all other categories of military grade weapons are nerfed creates unrealistic distortions in favor of using SMGs.

 

I suspect that at minimum, Volley 7+ should be automatic misses and there should be maximum burst limits of 20 rounds.   However, I don't know the 7e rules well enough to produce exact numbers.



#9 numtini

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Posted 27 November 2017 - 05:23 PM

Page 116

 

Let's say the gun has a capacity of 50, you get a success on 40 bullets fired, so rolling for half of shots fired. You roll 20 times?

 

Yes.

 

Chances of getting that many hits is insanely low though. Let's say you have an 80% skill. You chose to fire 6 volleys of 8.

 

1st volley, 80%, 2nd volley, 64%, 3rd volley 51%, 4th volley 26%, 5th volley 10%, 6th volley 5% (Note this is cocktail napkin math and probably off by a few percent, but hopefully you get the idea.)
 

Ok, that makes a good bit more sense, though it still means characters (whether PCs or NPCs) with high SMG skill are terrifyingly lethal.  

 

 

Yes, they are. On the other hand, dead is dead, and anyone with a 75 or 80 skill in a firearm can probably kill someone in a single round. Double barrel shotgun with slugs is 2 times 1d10+6 and the 6 guarantees a major wound. .45 auto at 80% is 3 times 1d10+2 at one penalty die which averages to around 15 points. Neither taking into account impales or crits, which would push the average damage up a bit.


Edited by numtini, 27 November 2017 - 05:24 PM.


#10 Professor

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Posted 27 November 2017 - 05:46 PM

I have to ask, 

 

Yes.

 

Chances of getting that many hits is insanely low though. Let's say you have an 80% skill. You chose to fire 6 volleys of 8.

 

1st volley, 80%, 2nd volley, 64%, 3rd volley 51%, 4th volley 26%, 5th volley 10%, 6th volley 5% (Note this is cocktail napkin math and probably off by a few percent, but hopefully you get the idea.)

 

Why does 80% drop to 64% to 51% etc? The rules state you start adding penalty dice and it's not until you fire the 4th volley that the skill check  is increased to Hard. 



#11 nclarke

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Posted 27 November 2017 - 06:28 PM

It's the mathematical effect of a penalty die. Do try and keep up.Professor ( perhaps you aren't a Professor of Mathematics :-) )



#12 Professor

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Posted 27 November 2017 - 06:39 PM

It's the mathematical effect of a penalty die. Do try and keep up.Professor ( perhaps you aren't a Professor of Mathematics :-) )

 

I thought that's what it meant but needed clarification. 

 

And hey, education is important but getting rules right is importanterer. 



#13 Celebrim

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Posted 27 November 2017 - 06:49 PM

Dead is dead, but there is a big difference between 18 or 24 average damage and 84 average damage.   One difference is that if your investigator has a 30% or 50% dodge, against the double barreled shotgun or the .45 automatic you have to make at least one dodge roll to have a chance of surviving.   But against the SMG, you have to make every dodge roll to survive (I guess that could be solved by allowing one dodge roll against every volley in the burst but still).   Another difference is that firing two bullets into a typical mythos monster that takes half damage from bullets or minimum damage from impaling weapons or has 6 armor probably doesn't stop it from eating you.  But firing 8 or 12 bullets with an average set of rolls into most mythos monsters chews them to pieces.  Having three times the average damage of the most effective firearms in other categories does make a difference, even if it probably doesn't matter which weapon the victim is on the end of in the case of an average antiquarian or elderly scholar. 



#14 numtini

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Posted 28 November 2017 - 02:46 PM

Dead is dead, but there is a big difference between 18 or 24 average damage and 84 average damage.  

 

Well... I knew it was deadly, but I hadn't quite done the math! Geez. Makes the lethality rating in DG look positively charitable! On the other hand, that kind of lethality seems pretty realistic.

 

And don't forget, all a dodge against firearms gets you is a penalty die.

 

The armor would count per bullet, so that helps a little.



#15 nclarke

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Posted 28 November 2017 - 04:50 PM

If you see a cultist wielding an SMG look for the largest rock to hide behind and dive for cover immediately. When he stops to reload that magazine pop out and let him have it with your trusty M1911 and hope his friend isn't on a different cycle with his reloads.







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