Automatic Fire in RPGs

[Whirlwind]

Which situations should it be more effective in modern RPGs or small-unit tactical wargames to fire assault rifles and submachineguns on full automatic? What effects should it have and what should the trade offs be?

A couple of questions inspired by a a very small survey I did earlier whilst thinking about some related issues

[Aethelflaeda was framed]

Close combat situations such as street fighting or other difficult terrain.  Night fighting or limited vision situations.  Full automatic is usually more wasteful of ammunition, and worn out barrels, for very limited returns.  Real tactics (as opposed to cinema tactics) stress limited, quick bursts.  US arms often had governors on them to prevent full auto usage.  I think full auto is more a hollywood thing or the product of panic than a proper tactical choice with an advantage in certain situations.  Maybe if you are facing a company sized banzai charge you could justify it.

Mick

[Whirlwind]

Thanks, I think that is a reasonable start.  So which effects are we thinking that implies for rules?

1 – More chance of hitting with automatic fire at close ranges? (increased chance of hitting)

2 – More chance of more hits per target with automatic fire at close range? (increased damage)

3 – The reverse being true at longer ranges; with use increasing chances of some form of failure/stoppage.

The company-sized banzai charge one is interesting – which effects should be associated with that?  The implication perhaps being that #1 should be reasonably generous but the downsides in #3 should be quite heavy (so it is a genuine trade off)…but maybe something else?

[Guy Farrish]

This is an interesting site – fun video and informative (?) results.

Full auto, semi auto and single shot AK

15yds range

It’s on a  US range but this is the reverse of a Gee Whizz! US weapons site.

Spoiler: 3 close together targets – two round burst gets more rounds on target at much the same speed as full auto mag dump (and you have a lot of rounds left) while semi auto single shots get best hit ratio but at nearly double the time.

When would you use full auto? Trying to scare someone or at less than 15yds range? Or if you were not military trained and wanted to get something on target as a last resort (although I suspect you’d lose any sense of aim after the first couple of rounds).

[Aethelflaeda was framed]

I think you could justify in “cinematic” rules both 1 and maybe 2 but the immediate malfunctions or ammo wastage should be a given,( range of fire isn’t really  a consideration to use or not, it’s discipline, opportunity and time to aim or not when firing on the enemy that dictates it).  one blast and the weapon is now useless.  Full auto expects most of the rounds to miss as you are spraying them.  highly dispersed and barely aimed.

 

In Space Hulk, the Autocannon could go full auto and can target everything in sight  ( one shot at each) but it uses up all of its ammo. IIRc they only had one reload, if that.  That strikes me as the best sort of approach.  It’s an act of desperation in a target rich environ with a limited avenue of approach.

 

There is also the suppressive nature of unaimed automatic fire (which again relies on limited bursts).  Going full auto for long periods destroys the barrels from over heating so cannot be sustained and you lose your threat.  To keep the other guy pinned, you just put out short random bursts and they will  keep their heads down.  It’s not always about hitting a target.

Mick

[Whirlwind]

That’s very useful, thanks Guy.

Think we can reasonably infer from the video that the semi-auto and the bursts are at ~maximum effectiveness here, whereas the full auto might have got more hits against a denser target array.  It also suggests that an RPG trying to model any of this will need quite a short ‘turn’ in whatever form. I guess you might use full auto at shorter range, although the burst might have done just as well – same deal for the untrained and using as last resort.

[Whirlwind]

Good points all Mick, thanks

[John D Salt]

As a general rule, historical data on combat shooting (of which I can find very little) seems to show a pretty clear relation between precision and rate of fire in small arms, as explained in my presentation “Precision vs Rate” to the 2019 Close Combat Symposium at Shrivenham. Essentially, faster-firing weapons score more casualties per second, but fewer casualties per round. The presentation doesn’t seem to be available on the interwebs, so people who want their own copy should PM me with their e-mail address.

To deal with the original question, I think there is a different answer for SMGs and for assault rifles.

It probably makes sense to fire SMGs (machine pistols, machine carbines) on full auto the whole time. Two data points support this.

The first is the report of results from trials in WO 291/476 “Comparison of rifle, Bren and Sten”. One trial involved snap shooting at a close-range moving target. The Sten scores similar numbers of hits per shot in burst fire as on singles, and fires more than twice as many shots.

5-sec exposure of 1x4ft moving target making a 50ft run at 17 yds
Weapon			Shots/run  Hits/run	Hits/shot  run P(hit)
Bren (single)		4	   1.4		0.35	   0.82
Bren (bursts)		6.8	   1.2		0.17	   0.72
Sten III (single)	5.6	   2		0.36	   0.92
Sten III (bursts)	12.1	   4.4		0.38	   1.00

The same paper reports hit probabilities at longer ranges, these being for a man-sized target at 200 yards:

Man-sized target at 200 yds
			single shot	4-rd burst
Rifle (unrested)	0.57		
Bren			0.60		0.90
Sten (unrested)		0.31		0.40
Sten (rested)		0.40		0.68

Singles here clearly get more hits per round than bursts, but the added P(hit) seems worth having against a fleeting target.

My other data point comes from a bunch of P(hit) calculations I did based on some remarkably comprehensive Soviet small-arms data I happened to find. The source for most of this is GRAU firing table No. 61, “Firing tables for 5.54 and 7.62mm weapons against ground targets”, USSR Ministry of Defence, Moscow, 1977. Data for the PPS-43 comes from a table at https://img.allzip.org/g/36/orig/7867167.jpg. The Russians do their ballisticking a bit differently from Western gravelbellies, giving dispersions by the 50th percentile rather than the standard deviation, and having 6000 mils in a circle rather than 6400 for NATO. Data for BKs (boekomplekti, ammo basic loads) comes from various sources. After torturing all these data sufficiently I come up with the following summary table, based on “average” shooters:

Weapon	CEP (NATO mils)	RoF (rds/min)		Fire time (min, s)	
	Single	Burst	Single	Burst	BK	Single	      Burst
PPS-43	1.16	1.61	30	100	210	7 min	      2 min 6 s
AKM	0.34	1.70	40	100	120	3 min	      1 min 12 s
AK74	0.23	1.26	40	100	180	4 min 30 s    1 min 48 s
RPK	0.33	0.94	40	150	320	3 min 45 s    2 min 8 s
RPK74	0.23	0.74	50	150	360	7 min 12 s    2 min 24 s

I include the “fire time” figures showing how long a BK would last if pooted off at the doctrinal rates to adumbrate (good word, adumbrate) the conservation problem. Incidentally while collecting this stuff I noticed that Soviet official rates and BKs seem to be a very good match for the amount of ammunition that would just bring the barrel to the point if overheating. It’s hard to believe that wasn’t deliberate.

P(hit) calculations using these data produce some grossly over-optimistic P(hit) figures (as you’d expect, this is range firing). The Russian tables give one dispersion figure for the first shot in the burst, and another for subsequent shots. Obviously if a single shot and a burst are aimed with the same precision, the first round of the burst makes its effectiveness equal to a single shot, and subsequent rounds are just gravy. I suspect that in real life bursts are less accurately aimed, but have no figures on it. If we glom up the expected dispersion of the first round and two subsequent rounds, I get results that show single shots always produce a greater P(hit) than 3-round bursts for all weapons except the PPS-43, were bursts are always better. Having a lower P(hit) does not necessarily mean fewer expected hits for a burst, and this might be a factor where prompt incapacitation is urgently desired.

We’ve had three tables full of numbers, so the innumerates should have been scared off by now, and I turn to more anecdotal evidence.

No less a personage than Heinz Guderian tells you how to use your MP-44:

“The principal value of the MP-44 lies in its accuracy and high rate of fire (22 to 28 rounds per minute) as a semiautomatic weapon, and in its alternate use as an automatic weapon, when it is fired in short bursts of 2 to 3 rounds (40 to 50 rounds per minute). Generally, the weapon is set for single fire. Bursts will be fired only when beating off an enemy assault, making a counterthrust against a penetration, in close combat, or at very short ranges during combat in trenches, towns, or woods. Strict fire discipline must be observed. Conserve ammunition!”

https://www.angelfire.com/art/enchanter/burst.html

The US Marines seem to agree:

https://nationalinterest.org/blog/the-buzz/the-us-marines-explained-us-when-fully-automatic-fire-23304

From “Analysis of M16A2 Rifle Characteristics and Recommended Improvements” May 1983, Osborne and Smith, Litton Mellonics, Fort Benning GA, we read:

“The M16A2 has less combat capability due to the elimination of full automatic fire. Full automatic fire enhances the ability of Army units to clear and defend buildings, to conduct final assaults on enemy positions, to defend against an enemy final assault, to conduct an ambush, to react to an enemy ambush, to engage an enemy helicopter or fast moving vehicle, etc.”

“AUTOMATIC FIRE
The elimination of automatic fire is considered to be a mistake. It solves no problem and creates many. There should be a very careful analysis conducted to determine just what the issues are. One of the reasons the M16 was acquired was because soldiers in combat felt they were being outgunned by an enemy armed with an automatic AK47. Many times it is a very close call as to which side has fire superiority. The psychological impact of fully automatic fire can often make the difference in the unit’s perception of how effective their fire is. There are also some data to suggest that a soldier is more willing to expose himself and return fire if he has a fully automatic weapon, as opposed to a more controlled way of delivering fire. It has been well established that, during World War II and Korea, a large percentage of soldiers failed to fire their semi-automatic weapons during some enemy contacts. In Vietnam, armed with a fully automatic weapon, almost all soldiers returned fire. Much of the Vietnam firing was “wasted”, i.e., it didn’t hit anybody, however, it was a rare exception when individuals or units got into trouble because they had expended all of their available ammunition. The point can be made that there is nothing wrong with firing a lot of bullets if ammunition stocks are retained at safe levels. Considerable ammunition is conserved when 85% of a unit fails to fire their weapons, and considerable ammunition is expended when all unit members engage targets with full automatic fire. While good training and good leadership should keep the Army between these two historical extremes, the question of which alternative is wiser should be addressed.”

Does that answer the question?

All the best,

John.

[Whirlwind]

That’s great stuff, thanks John. That gives me some great things to work with (as does some of the earlier info) about how to torture the game mechanics into giving something more useful in terms of character decision-making and combat resolution here.

The last section on automatic fire does raise some very important but much more difficult questions that are a bit harder to fit into average RPG mechanics – although no reason not to try I suppose.

[John D Salt]

Wait, there’s more. To add more blather I forgot the frst time…

Tony Jeapes (author of “SAS: Operation Oman”) wrote an interesting piece I no longer have access to while he was in charge of the BATT in Oman, in either the British Army Review or the Army Training Quarterly (or whatever it was called). It described the section organisation he used of two fireteams, each with a GPMG and three AR-15s. In a phrase I hope I recall accurately, he said that people getting up to go forward had to do so against “Not the pop-pop-pop of rapid musketry, but the mind-shattering noise of automatic fire.” I think it was also Tony Jeapes, or perhaps Ran Fiennes in “Where Soldiers Fear to Tread”, who mentioned the need to replace the Trucial Oman Scouts’ Lee-Enfields when they started meeting Adoo armed with AKs, saying that against AKs “A soldier needs an automatic weapon just to make himself heard”.

From “The Development of Combat Related Measures for Small Arms Evaluation”, Ronald D Klein and Charles B Thomas, US Army Infantry Board, Fort Benning, GA, undated:

“The next effort was to examine the individual effectiveness of each round of the different burst sizes; these are shown in Figures 9 and 10. The highest single-round effectiveness for both weapons is achieved with the single round of a semiautomatic trigger pull. The second most effective round for Rifle A is the first round of a 2-round burst; the same phenomenon for the first round of automatic fire for Rifle B was not observed. It could be expected that all first rounds of a burst and the single round of a semiautomatic trigger pull would be identical in terms of the probability of achieving a hit. The effort required to acquire a target, position the weapon, align the sights, and squeeze the trigger are exactly the same regardless of the mode or the number of rounds that follow the first round. These data do not support this reasoning and, in fact, show that first-round effectiveness is related to the number of rounds that follow and the effectiveness of the following rounds. Generally, individual round effectiveness drops very rapidly as the burst of fire continues in a quick-fire enfgagement. Bursts of four or more rounds are relatively ineffective against point targets.”

“An Experimental Review of Basic Combat Rifle Marksmanship: MARKSMAN, Phase I”, James W Dees, George J Magner and Michael R McLuskey, HUMRRO, Alexandria, VA, March 1971.

“DAY FIRING-SINGLE TARGETS
Mode of Fire
Mode of Fire (semiautomatic vs. automatic) was studied in Experiments 4, 11A and 111B. Against non-moving, single targets in the daytime, from most firing positions, the semiautomatic mode was superior to the automatic mode in both the time required for a hit and the number of trigger pulls required for a hit from 50 meters out. Within 50 meters, there was little difference between the two modes, either in time to first hit, or in trigger pulls to first hit, within 25 meters. The automatic mode was faster than the semiautomatic mode, in time to first hit up to 50m. Figures 4 through 7 illustrate the interaction between mode and target distance.
Time to first hit is probably the more important of the two criteria examined combining both speed and accuracy. The time to first hit as a function of target distance in Experiment 4 is plotted in Figure 4. These values are the means for the “coarse aim” technique for all of the five firing positions tested. Beyond 50 meters, the semiautomatic mode was superior in both speed and accuracy, becoming more superior with increasing distance. Within 25 meters, the automatic mode was superior in time to first hit (Figure 5) although not in trigger pulls to first hit (Figure 7). The superiority of the automatic mode of fire within 25 meters is slight, but significant (p<.05) (Figure 5).
Mean time to first hit data as a function of target distance for Experiments 11A and 11B is provided in Figure 5; the “aimed fire” portion of Experiment 11B was averaged across all firing positions for this graph. The differences between the positions used in Experiments i and 11B possibly account for some of the difference between Figures 4 and 5. Experiment 11A provided the only examination of the semi-automatic versus the automatic mode within 25 meters. The data for Experiment 11B on the same graph support the conclusion reached in Experiment 4 that semiautomatic fire is superior to automatic fire with the M16 rifle, beyond 50 meters (Figure 6).”

Fig 4	Time to first hit, experiment 4					
Range (m)	25	50	75	100	150	200	275
Semi-auto	2.5	3.0	3.5	4.6	6.2	7.5	9.0
Auto	        2.2	3.2	4.1	5.5	7.5	9.1	11.4
									
Fig 5	Time to first hit, experiments 11A and 11B				
Range (m)	10	15	20	25	50	75	100	150	200
11A Semi-auto	1.25	1.52	1.81	2.01					
11A Auto	1.07	1.38	1.58	1.83					
11B Semi-auto					3.0	4.0	4.7	7.5	10.7
11B Auto					3.3	4.8	5.8	8.2	11.3
									
Fig 6	Trigger pulls to first hit, experiment 4
Range (m)	25	50	75	100	150	200	275
Semi-auto	1.2	1.4	1.5	1.8	2.3	2.6	3.0
Auto	        2.9	3.8	5.7	6.4	7.4	8.8	10.2	
									
Fig 7	Trigger pulls to first hit, experiments 11A and 11B
Range (m)	10	15	20	25	50	75	100	150	200
11A Semi-auto	1.14	1.21	1.29	1.54				
11A Auto	1.05	1.14	1.29	1.46				
11B Semi-auto					1.0	1.3	1.6	2.1	2.8
11B Auto					1.3	1.6	1.8	2.6	3.6

“DAY FIRING-MULTIPLE AND AREA TARGETS
Mode of Fire
In Experiments 4, 11A, and IIB it was determined that the semiautomatic mode of fire is superior in time to first hit and total number of hits as compared with the automatic mode of fire against single targets in the daytime. In Experiments 9 and 10 it was concluded that the automatic mode of fire is superior against single targets at night and in limited visibility conditions.
It was reasoned that the automatic mode of fire was superior at night because the targets were indistinct, resulting in less accurate aiming, thereby increasing the value of maximizing chance hits by the use of automatic fire; further, where the target was visible, the semiautomatic mode of fire gave a higher hit rate than the automatic mode because it was possible to re-lay the weapon for follow-up shots more rapidly in the semiautomatic mode. Multiple targets and area targets in the daytime have characteristics of both of these situations, so it was necessary to examine them in the daytime to determine which mode of fire would maximize the number of hits and the number of hits per unit time.
In Experiment 14A, the semiautomatic and automatic modes were compared at four target distances and two distribution densities for multiple targets. It was found that semiautomatic fire resulted in more hits per second than automatic fire. Furthermore, semiautomatic fire resulted in two to three times as many total hits as automatic fire, and resulted in better fire distribution as well. In addition, increasing the target density resulted in an even greater superiority for semiautomatic fire. Ammunition expenditure was held equal in both modes.”

“NIGHT FIRING
Mode of Fire
In Experiments 9 and 10 semiautomatic vs. automatic fire at might was studied. It was concluded in both experiments that automatic fire using the three-round burst was superior to semiautomatic fire in total number of hits, and in hits per trigger pull. In addition, it took no longer to fire a three-round burst of automatic fire than to fire a single round in the semiautomatic mode at night. The conclusion must be that in a time-critical situation at night, automatic fire using the three-round burst is more likely to achieve a hit than semiautomatic fire. However, since automatic fire uses more ammunition than semiautomatic fire, the superiority of automatic fire at night will be compromised by the additional ammunition expenditure.”

It makes intuitive sense that the advantage of high precision should fade and eventually pass to high rate as the ability to aim accurately decreases, whether through psychological stress, short aiming time, or uncertainty as to the target’s precise position because of poor visibility or cover. I suspect that in real close combat a lot of shooting is what the Rhodesians called “drake shooting”, that is, brassing up likely cover. All the comparisons cited are based on hits on target, and I suspect that the apparent advantage of semiautomatic fire would not be so great if suppressive effect could be included.

All the best,

John.

[Whirlwind]

Thanks John, that is very interesting.

Within 25 meters, the automatic mode was superior in time to first hit (Figure 5) although not in trigger pulls to first hit (Figure 7). The superiority of the automatic mode of fire within 25 meters is slight, but significant (p<.05) (Figure 5).

I am slightly struggling to parse the first sentence here. Is the implication that both auto and SA fire hit on the first shot but the auto firer just fired first?

[Patrice]

Very interesting info and discussion, thanks (…my own personal experience being long ago with the French MAT 49 SMG, unable to do anything else than very short bursts but quite funny to fire).

Regarding RPGs, a question is: do you really want to include the difference between full auto and short bursts in the rules? I would assume that the character instinctively does what’s most appropriate, it happens so fast that I would not ask players to choose and have to look at different charts etc.

Single shots are a different matter, but for limitation I would only give an advantage if the character is an elite shooter; or for no more than one character in the player’s squad each game turn, assuming that all soldiers wouldn’t fire single shots in salvoes exactly at the same time.

But that’s me. 🙂

http://www.argad-bzh.fr/argad/en.html
https://www.anargader.net/

[John D Salt]

Whirlwind wrote:

Thanks John, that is very interesting.

Within 25 meters, the automatic mode was superior in time to first hit (Figure 5) although not in trigger pulls to first hit (Figure 7). The superiority of the automatic mode of fire within 25 meters is slight, but significant (p<.05) (Figure 5).

I am slightly struggling to parse the first sentence here. Is the implication that both auto and SA fire hit on the first shot but the auto firer just fired first?

Given that the number of trigger pulls to first hit for auto fire is so high even at the close ranges, I think it must be that the auto firers often managed to get off a couple of bursts before the semi-auto firers had got off their first shot. This strongly suggests to me that the accuracy of the first shot of a burst should not be the same as a single shot, as the burst is presumably got off more hastily and so more coarsely aimed.

For an RPG I wonder if it would be possible to come up with some kind of bidding system, whereby each turn players place a bid for each character to have first shot. Better bids (quicker times) can be made at the cost of sacrificing accuracy. Quickest shots are resolved first, and the target always has the option of becoming wholly or partially suppressed, sacrificing the accuracy of any shooting they still have to do or reducing their movement, in exchange for a lesser chance of getting whacked. I think player caution would lead to lethality much being lower than what the weapons are theoretically capable of, although unengaged shooters (including ambushers on the first turn of an ambush) could be brutally effective.

All the best,

John.

[Whirlwind]

Patrice wrote:

Regarding RPGs, a question is: do you really want to include the difference between full auto and short bursts in the rules? I would assume that the character instinctively does what’s most appropriate, it happens so fast that I would not ask players to choose and have to look at different charts etc.

Yes, it matters in some games, particularly where there are trade offs between effectiveness and ammunition expenditure where the latter is scarce (so Twilight 2000); plus up to a point we need to understand the differences to model both, even if we then make the expenditure an outcome rather than an input. But not all games, for sure.

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