Home Forums Modern Rifles and LMGs — accuracy or weight of fire?

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  • #106015
    John D Salt
    Participant

    Arising from the question about the suppressive value of subsonic rounds, the old point of contention between accuracy and weight of fire raised its head. The following numerical exercise might explain the reason why I think the German-style belt-fed lashings-of-bullets proper LMG approach is the right one, rather than the William Tell-Bowmen of England-Deadeye Dick individual rifleman precision school. The argument does not even appeal to the obvious point that it is more fun to have a weapon that goes dacka-dacka-dacka than one that just goes bang.

    To investigate the relative value of accuracy and rate of fire in infantry weapons, I took a look at three small sets of data I have from combat and from a very realistic trial. Combat shooting data of this kind is rarer than rocking-horse manure, so if anyone can tell me any additional sources, I would be limply grateful.

    The first lot comes from National Archive piece number WO 291/1668, “Performance of small arms weapons including .280 (7mm) rifle, used in machine carbine role in Malaya”, 1953. This gives the number of rounds per enemy casualty inflicted in 100 patrol actions and 154 ambushes where such casualties were inflicted (there were also 243 patrols and 161 ambushes that inflicted no casualties). About 20% oof the successful ambushes were at night. Average engagement ranges were about 70m for patrols and 30m for ambushes.

    The second lot are from “Bang on Target: Infantry Marksmanship and Combat Effectiveness in Viet Nam”, Dr Bob Hall and Dr Andrew Ross, Australian Army Journal Vol. VI no. I, pp. 139 2009. This is a summary of some 4100 contacts by 1st Australian Task Force (1ATF)in Vietnam. Those contacts for which data are given are divided into attacks on enemy positions, security contacts, patrol encounters, and ambushes. I have discarded the attacks on enemy positions to try to make the situations more comparable to the British figures from Malaya; this would reduce the sample size to about 3690, still plenty. 80% of all engagements occurred below 30m, and about 42% of ambushes occurred at night.

    The final set, although only from a trial rather than combat, seems to have been conducted under exceptionally realistic conditions, and produces numbers comparable to the two combat sources above. The source is “Jalkaväen tulen vaikutuksesta” (On the Effect of Infantry Fire), 1954, in: “Computational Methods for Tactical Simulations”, Esa Lappi, Helsinki, 2012. The trial was conducted at a range of about 200m, and so I have disregarded figures calculated for other ranges.

    The rate of fire figures have been assumed from doctrinal norms for the Malaya and 1ATF data, but are stated in the Finnish trial report. The exact types of weapon used in the Finnish trial have been assumed; the report gives only the general class.

    Weapon			Class	RoF    Rds/cas	Mins/cas
    ———————————————————
    Bren			LMG	120	259	 2.16
    M1/2 Carbine		SLR	 20	 83	 4.15
    Owen/Sten		SMG	 40	304	 7.60
    No. 5 Rifle		BR	 12	130	10.83
    ———————————————————
    M60			LMG	200	625	 3.13
    M16			AR	 40	286	 7.15
    SLR			SLR	 20	194	 9.70
    ———————————————————
    MG-42			LMG	300	556	 1.85
    Lahti-Saloranta M26	AR	 60	323	 5.38
    Suomi M31		SMG	100	556	 5.56
    SVT-40			SLR	 20	164	 8.20
    Mosin Rifle		BR	  8	 82	10.25
    ———————————————————
    

    The different circumstances under which each nation’s data were collected must be borne in mind; nonetheless, several distinct patterns seem perceptible. Generally, faster-firing weapons need more bullets to produce a casualty, but can do so in a shorter time. This seems to indicate that the faster-firing weapons, while less efficient, are more effective, even without making any allowance for the greater suppressive effect of burst fire.

    The relative values of casualty infliction rates indicate that LMGs are worth 4 to 6 times as much as bolt rifles, and personal automatics 50 to 100% more than rifles.

    The M1 or M2 carbine in British service in Malaya shows extremely, I would say anomalously, good results. The original report suggests that this outstanding performance may be due to the carbine usually being issued as a leader’s weapon. Otherwise, the advantage of SLRs over bolt rifles appears small, 15 to 30%.

    If one assumes standard ammunition loads based on historical examples, the relative values of stowed kills seem to understate the value of MGs compared to Rowland’s HA results of about 0.5 per rifle and 4.0 per MG. The slower-firing weapons do well on stowed kills because they need relatively few bullets per casualty. The relative times for which fire can be sustained seem believable in comparison with the order in which weapons run dry reported in S L A Marshall’s “Commentary on Infantry Operations and Weapons Usage in Korea, Winter of 1950-51”, ORO-R-13, Johns Hopkins 1951, with rifles outlasting automatics.

    All the best,

    John.

    #106016
    grizzlymc
    Participant

    That’s excellent stuff and would seem to suggest that the rule of thumb that the LMG is half the section’s firepower is about right. Your 15% advantage with the MG42 v BREN seems to come at a huge weight cost, is it worth an extra ammo bearer? And it would be interesting to know why the M60 performed so poorly.

    #106079
    John D Salt
    Participant

    Bear in mind that the circumstances under which each set of data was collected are very different. It seems safe to compare weapons with other weapons in the same data set; one needs to be a lot more cautious about comparisons between them (although I thought the figures for the various rifle types were not so different as to make such comparisons worthless).

    On the performance of the M60 with 1 ATF, Bob Hall says (original article available at https://www.army.gov.au/sites/g/files/net1846/f/aaj_2009_1.pdf ):

    A generic ‘shots per casualty’ figure does not tell us the whole story about marksmanship in combat shooting. The role of the GPMG M60 was to lay down dominating fire to suppress the enemy and permit manoeuvre, which is why the table shows it expending large numbers of rounds to produce an enemy casualty. The M16 and the SLR on the other hand were more ‘surgical’ in the type of fire they produced requiring fewer rounds per enemy casualty. The M16, being capable of fully automatic fire, shows a slightly higher ‘shots per casualty’ ratio than the semi-automatic 7.62mm SLR. The quality of marksmanship, as measured by ‘shots per casualty’ ratio, therefore depends heavily on weapon type, ability and function in the fire fight. This also reminds us that when producing fire in contact, the section functions as a team. It is because the M60 lays down suppressive fire — at the cost of high ammunition expenditure for low casualties — that the M16 and SLR can achieve more surgical killing effect.

    You read that right, he described two or three hundred rounds per casualty at ranges under 50 metres as ‘surgical’. Elsewhere he cites a source from operations during the Indonesian confrontation as stating that Commonwealth forces required something like 750 rounds to produce a casualty overall. It doesn’t sound great, but recall that they still managed to beat the Indonesians like a set of bongos. There really is a vast difference between shooting performance on the range and on ops.

    I am also reminded that the WRG Infantry Action 1925-75 rules gave LMGs a reduced firepower score at very close range, and wonder if the unhandiness of the M60 is beginning to tell against it at the very close ranges of most 1 ATF fights. I suspect that the MG advantage would be greater at more “normal” engagement ranges — I am accustomed to reckon the gun as more like two-thirds or three-quarters of section firepower. I would also treat the LMG figures in the Finnish data set with extra caution, as this is a class of weapon that did not seem to appear in the actual trial, and I imagine the figures were constructed from assumptions (which would explain the suspicious rds/cas similarity with the SMG). In real life I would expect an MG-42 to put a higher proportion of rounds on a head-and-shoulders target at 200m than any SMG, even one as good as the Suomi, ever could. The rate of fire they give for it seems a bit mental, too.

    Obviously the data is highly unsatisfactory in all sorts of ways; but that’s what there is. If there is any more rounds-per-cas combat shooting data like ths available, I’ve never heard of it. Indeed until I came across Bob Hall’s article, I assumed that such data fell firmly into Stewart Robinson’s “Class C Data”, that which is neither available nor collectable.

    All the best,

    John.

    #106086
    Norm S
    Participant

    Someone who had used a Bren Gun told me that you had to wiggle the thing to stop the second bullet going through the hole made by the first bullet – some artistic license no doubt, but probably extrapolated from experience and reputation.

    #106109
    grizzlymc
    Participant

    Agreed John, this is like Hughes dissections in “Firepower”. A pair of undies with holes in them is better than no undies at all.

    #106112
    John D Salt
    Participant

    Agreed John, this is like Hughes dissections in “Firepower”. A pair of undies with holes in them is better than no undies at all.

    A pair of undies *without* holes in them makes it remarkably difficult to put your legs in.

    I once discovered this in Crawley hospital when I was mistakenly issued a paper cap instead of paper underpants while getting ready to be operated on. Having discovered the lack of leg-holes, I did the logical thing and put the thing on my head, assuming that I had been misinformed as to the procedure. There was a brief moment of consternation among the surgical team, who suspected that they might have overdone the pre-med atropine if the patient had decided to put his underpants on his head.

    All the best,

    John.

    #106125
    Dal Gavan
    Participant

    G’day, gents.

     

    John, having used the M-60 and L4A4 Bren (and the MAG-58), the discrepancies you noted are more about the design philosophy of the weapons than anything else.

    The M-60 was a General Purpose Machine Gun. It was designed to maximise dangerous space and to create a useful Beaten Zone  (BZ) at normal engagement ranges, ie out to 600m. So with the sights set at 600m the culminating point (ie highest point) of the round was 1.2 m and the beaten zone was 1m X 67 m. Being belt fed, at a sustained RoF (200 rdpm bursts of 20 rounds) was feasible and that allowed the formation of the BZ. At the section/squad level the gun was used to either put suppressing fire on the enemy or, when in a defensive position engaging the enemy using fixed lines or limits, so as to maximise the dangerous space and therefore number of casualties.

    The Bren was a Light Machine Gun. It was a magazine fed weapon (30 rounds per mag’) that was unable to provide sustained fire for very long. By the book we carried 10 mag’s, but 15 to 20 in real life (getting extra mag’s was getting difficult by 1980) and they got used up quickly. Once they were empty it meant reloading the mag’s- not something you want to do when in contact, so the No 1 was constantly getting slapped on the head and told to keep the bursts down below 10 rounds. The Bren  was designed to suppress the enemy as well, by putting concentrated and accurate burst fire onto a specific location. The stat’s speak for themselves- the culminating point was about the same as the M-60 at 1.1m (from memory- it may have been 1.3) but the beaten zone was 0.5m by 93m (again from memory- if someone has different data I’ll be glad to be corrected) and took about a full mag to get a BZ to form. Great for putting bursts into slits or embrasures, or enemy LMG pits, less good for for interlocking arcs or firing on fixed limits.

    The VN veterans in the battalion (and in ’75 there were a lot of them, about 30% of the battalion) also made the point that after Claymores “the gun”- an M-60 from 1965 to when the last blokes left in 1973- was the main killer in ambushes (if it was well sited- if it wasn’t it still made some useful noise).  The SLR’s and Owen/M-16 (which replaced the Owen in ’67) were best used for double tapping when clearing the killing zone. So while the M-60 may have taken more rounds to cause a casualty, it was also causing more casualties than the other weapons combined.

    IMHO we took a step backward going to the MAG-58m (less well balanced- so you needed a sling to patrol with it, no forehand guard to protect left hand and fingers from a hot gas chamber and a pain to keep clean) at section level, although the MAG-58 was a much better sustained fire (ie tripod mounted) GPMG.

    Cheers.

    Dal.

    • This reply was modified 1 year, 11 months ago by Dal Gavan. Reason: Illiterate fingers
    • This reply was modified 1 year, 11 months ago by Dal Gavan. Reason: Same problem- finges
    #106128
    grizzlymc
    Participant

    Dal, I believe you are an aussie. I wasn’t aware that we used the 7.62 Bren after Vietnam, did we not have enough M60s?

    #106129
    grizzlymc
    Participant

    Agreed John, this is like Hughes dissections in “Firepower”. A pair of undies with holes in them is better than no undies at all.

    A pair of undies *without* holes in them makes it remarkably difficult to put your legs in.

    I once discovered this in Crawley hospital when I was mistakenly issued a paper cap instead of paper underpants while getting ready to be operated on. Having discovered the lack of leg-holes, I did the logical thing and put the thing on my head, assuming that I had been misinformed as to the procedure. There was a brief moment of consternation among the surgical team, who suspected that they might have overdone the pre-med atropine if the patient had decided to put his underpants on his head.

    All the best,

    John.

    When they cut half my leg off, I got neither undies nor head cap.

    #106149
    Just Jack
    Participant

    Dallas,

    “IMHO we took a step backward going to the MAG-58m (less well balanced- so you needed a sling to patrol with it, no forehand guard to protect left hand and fingers from a hot gas chamber and a pain to keep clean) at section level, although the MAG-58 was a much better sustained fire (ie tripod mounted) GPMG.”

    We had issues with our version, the M-240G, with the chamber swelling and making it very difficult to change barrels. More than once I had to stand up and present my backside to the enemy in order to grab the barrel release and kick the muzzle in order to free it.

    V/R,

    Jack

    #106155
    Dal Gavan
    Participant

    Happy Friday, Gents.

    Grizzly:

    Dal, I believe you are an aussie. I wasn’t aware that we used the 7.62 Bren after Vietnam, did we not have enough M60s?

    Yes, mate, I’m Aussie. The L4A4 was issued to non-combat arms units, I think, with 60’s going to arms corps units. And support units, such as Base Workshops and Supply Battalions only got L1A2 AR’s, not even the Bren.

    In the early to mid 80’s all the M-60’s were withdrawn as well. The operating rods were badly enough worn that guns would run away if you just took the safety off. The MAG-58 was “coming in” (as usual, late) so some idiot staff officer had probably decided not to buy spares. As a result, at least in 6TF (now 7BDE), we got L4A4’s instead. We had M-60’s back by mid ’80 in 8/9, but even in 2/4 admin company, BN HQ and int section still had Brens until the MAG-58’s finally started to show up.  Some CMF battalions probably kept Brens unto the MAG-58’s came in- 51 RQR (before it became FNQR) still had them in late ’82, when we supplied a couple of instructors for their subject courses.

    Also in ’81 Barry Caligary was CO 1 RAR and he introduced L4A4’s as the No 2 rifleman’s weapon, to give the rifle group some automatic capability. It didn’t work that well, from what my mates in 1 were saying.

    Jack:

    We had issues with our version, the M-240G, with the chamber swelling and making it very difficult to change barrels. More than once I had to stand up and present my backside to the enemy in order to grab the barrel release and kick the muzzle in order to free it.

    Blow that for a game of soldiers, mate! Most stoppages are bad enough, but having to play silly games to get the barrel out is going a bit far. I hadn’t heard of that one, but I didn’t have much to do with the MAG-58- just enough to miss the ’60. The MAG-58 came in, in late ’82 or so, and I had to leave infantry in ’83.

    Did they solve that problem?

    Cheers.

    Dal.

    #106159
    John D Salt
    Participant

    When they cut half my leg off, I got neither undies nor head cap.

    Oooh, bugger. Hope they gave you plenty of happy drugs.

    John, having used the M-60 and L4A4 Bren (and the MAG-58), the discrepancies you noted are more about the design philosophy of the weapons than anything else.

    The M-60 was a General Purpose Machine Gun. It was designed to maximise dangerous space and to create a useful Beaten Zone (BZ) at normal engagement ranges, ie out to 600m. So with the sights set at 600m the culminating point (ie highest point) of the round was 1.2 m and the beaten zone was 1m X 67 m.

    Hello there Dallas, and welcome to Mike’s House of Fun.

    It’s not really possible, as I pointed out to grizzlymc, to make direct comparisons between the 1 ATF and Malaya data, given the different circumstances under which they were collected. I am sure (and Bob Hall’s article mentions this) that a lot of the aparently high expenditure of ammunition from 1 ATF was due to what the South Africans call “drake shooting”, that is, shooting into areas of the jungle where there was good reason to believe the enemy to be.

    As I am sure regular reader are heartily sick of hearing, the L4 and L7 were what I used back in the good old days I was allowed out at weekends to run around with machine guns in the fresh air at government expense. At the time, in British service, there was no difference at all between the doctrinal rates of fire for the LMG and the GPMG in the light role. They fired the same bullet, and I thought at the same muzzle velocity, although “Jane’s Infantry Weapons” for 1975 credits the GPMG with an edge of 50 ft/s (15 m/s), and a barrel longer by an eighth of an inch (3.2mm).

    I have no figures for the beaten zone dimensions of the Bren, but “Infantry Training Volume III Skill at Arms (Section and Platoon Weapons) Pamphlet No. 17, The General Purpose Machine Gun”, Army Code No. 71058 (Revised 2002) gives the following for the GPMG (all figures in metres):

    Range	Width	Length
     600	 2.3	 258
    1100	 4.2	 142
    1800	 6.9	 112
    2500	 9.6	 104
    

    The definition of beaten zone used is the 90% zone.

    A rather crude trajectory diagram in the same publication has too coarse a horizontal scale to read off the maximum ordinate (culminating point) at 600m, but I’d be very surprised if it is more than a metre.

    The document also shows the doctrinal rate in the light role as 100 rds/min rapid, 25 rds/min sustained, but I don’t think anyone is going to have an L7 fire slower than an L4. The final sign of “change and decay in all around I see” is that the soldier photographed demonstrating various evolutions with the gun has his boots laced up criss-cross fashion. Never would have been allowed in my day, mumble blether moan.

    All the best,

    John.

    #106286
    Dal Gavan
    Participant

    G’day, John, and thanks for the welcome.

    Agreed, us old blokes and our memories can be a bore. But in this case it’s something I did for 8 years, so there’s hopefully some relevance (fading memory accepted, hopefully. 🙂 I’ll try to keep this shorter.

    It’s not really possible, as I pointed out to grizzlymc, to make direct comparisons between the 1 ATF and Malaya data, given the different circumstances under which they were collected.

    Australian battalions were in Malaya and Borneo as well, mate, and indeed we had a reinforced rifle company at Butterworth, doing what is officially described as training, up until Chin Peng surrendered in ’89. There’s still a company there, but now that can be drawn from any arms corps unit or even conglomerated sub-units, from the ARes and ARA and their sole role is training with the Malaysians and Thais.

    I don’t know if there have been any studies done that compare the fire effectiveness in each area or not. When I get back to work I’ll see if there’s anything I can find, and post, if you’re interested?

    I am sure (and Bob Hall’s article mentions this) that a lot of the apparently high expenditure of ammunition from 1 ATF was due to what the South Africans call “drake shooting”, that is, shooting into areas of the jungle where there was good reason to believe the enemy to be.

    That’s possible. It was actually taught as a method of measuring the enemy’s frontage in really close country or bunker systems, the idea being to fire a few rounds rapid and see if there was a response. It was a last resort, though, when eyeballing the position was impractical. Personally I think the use of deliberate ambushes as a primary tactic (each member puts a full mag/belt into the killing ground at rapid on initiation, usually by claymores, and follow up with another at any muzzle flashes from the ground or the flanks), and the tactic of “swamping” bunkers (or even suspected bunkers) to try to suppress them, may have been been more likely- they were definitely more common based on my training and “educational war stories” from various instructors.

    At the time, in British service, there was no difference at all between the doctrinal rates of fire for the LMG and the GPMG in the light role.

    Much the same here. While the 60’s were sidelined we used the Bren as the section gun, but the need to refill magazines limited the rate of fire. With the 60 we carried seven to 10 belts, but we were lucky to have 500 rounds for the Brens, and rarely more than 15 mag’s to put them in ( at the start we’d be lucky to have six or seven).

    They fired the same bullet, and I thought at the same muzzle velocity, although “Jane’s Infantry Weapons” for 1975 credits the GPMG with an edge of 50 ft/s (15 m/s), and a barrel longer by an eighth of an inch (3.2mm).

    I think I remember having a memory, once. Taught MV for the SLR and the M-60 I think was the same- 1760fps- but I can’t remember the Bren (or MG-58).

    MAG-58 BZ data.

    Thank you, mate! I had a look but couldn’t find the data. The BZ on the MAG-58 made it very, very good SFMG weapon, though we only used it out to 2400m I think. They used to do an GPMG demo’ at Singleton, when George Mansford was the CI of the DFS Wing (or whatever it was called then) in the mid-late 70’s. There were about 30 figure 11 targets, tactically spaced, with a couple of balloons taped to each one and a section of two SFMG would each fire 300 rounds sustained from 2 km away (one gun fires it’s burst and then the next fires its, so there’s constant rounds on target). The balloons and the ground strikes gave a good indication of the beaten zone and what it meant. The demo’ also included the effects of grazing fire, plunging fire, etc, on different target groups on different terrain, from guns on bipods. I hope they still do something similar.

    Cheers and all the best for Xmas and the new year, mate.

    Dal.

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