Shooting a Colt CMG-3 at James D Julia

In the mid/late 1960s, Colt was manufacturing AR-15 rifles and wanted to supply light machine guns to go with them – so they developed the CMG-2 (“Colt’s Machine Gun”). The CMG-2 competed against the Stoner 63 in trials for the Navy SEALs (among others), and narrowly lost out. It was a very well designed and thought-out weapon, but not *quite* as good as the Stoner.

A few years later in the early/mid 70s, Colt brought the design back in response to a request for a belt-fed 7.62mm machine gun for special operations units. Something with the firepower of the M60 was desired, but in a lighter package. Colt took their CMG-2, scaled it up to 7.62mm NATO caliber, and redesignated it the CMG-3. A total of 5 guns were made, and they went into military testing.

Unfortunately for Colt, the design wasn’t quite as simple to scale up as they had hoped. The CMG-3 was determined to have a service lifespan of about 35,000 rounds – a third of what was required. Around that point, the receivers would fracture at the front trunnion. By the time Colt had worked out a new design to strengthen the guns without adding too much weight, the contract opportunity had passed, and the improved version was never made.

Of the five guns originally made, I believe only two still exist. This one is serial number 1, and I was privileged to get permission of the consigner to test-fire it on camera. In my opinion, it is a fantastic gun. At only about 18 pounds it is remarkably light for a 7.62mm beltfed, and quite simple to shoot from the shoulder. As with the SMG-2, it’s internals are a parade of clever elements. Have a look:

57 Comments

  1. Fascinating stuff, Ian! Thanks for posting footage of such a unique lmg. Looks pretty controllable for such a light machine gun. I wonder why didn’t Colt try to export the improved version once they knew the contract opportunity had passed… Do you have any clues about it? Perhaps the non-adoption by US forces was too heavy a blow for the marketing department of the company vis-a-vis prospective foreign customers.

  2. A most impressive design — the general user-friendliness is quite obvious, too. What a pity the proposed improved version never made it into service ( yet another case of bad “market timing” ).

    Considering that this is just one of only two known examples in existence, one must admire the incredible generosity of the current owner in allowing the CMG-3 to be live-fired for the edification of all concerned.

  3. Ian, not only are you are a jammy, jammy barsteward, you also have the best job on the internet.

    The symmetrical firing pin is such a good idea I am amazed no one else has borrowed it for other service weapons.

    • The “double-ended” firing pin was first used in the Mendoza C-1933/34 7 x 57 Mauser LMG in the 1930s;

      http://www.forgottenweapons.com/light-machine-guns/mexican-mendoza-lmg/

      The later RM-2 in .30-06 also has this feature.

      And yes, it’s really surprising that others haven’t used it. It would have been a big improvement over the one on the M60 GPMG, which can easily be installed bass-ackwards, at which point it fires one shot and that’s it. The same as the M60 gas piston assembly; put in in the wrong way around, and you have a manually-operated, straight-pull, overweight, belt-fed bolt-action rifle.

      There really are only two practical ways to build a small arm. Either the parts should only go in one way and have no possibility of going in any way but the right way (a characteristic of Browning and Mauser designs- look at the 1911, the BAR, The M2 “fifty”, and the Mauser “Broomhandle”), or they should work correctly no matter which end goes in first, as on the Mendoza LMGs.

      It’s especially critical on combat weapons, particularly MGs. S**t Happens in combat; sooner or later you’ll have to at least field-strip the bugger under fire to get it working again, and a part that can go in wrong-ways-round and stonewall the whole production can get you and everyone else on your side ending up as clients for Graves Registration.

      It’s really interesting how many small arms designers never seem to figure this one out. Like the designers of the M60, for instance.

      cheers

      eon

      • Good way to sum things up, eon. Sadly for the M60, some of its internal workings were purportedly inspired by the FG-42 which was actually quite fragile for a battle rifle. Combine the lack of understanding of the original material with the usual stupidity of “laissez-faire” procurement of parts and ammunition (done way too much nowadays by sleazy politicians and bureaucrats) and you have a train wreck waiting to happen… Colt probably needed to account for stress distribution.

        Some aircraft manufacturers who make planes and helicopters for the military prevent dirt-cheap part subcontracting by keeping some of their most important material specifications out of the government’s hands so that politicians can’t embezzle funding allocated to aircraft procurement (just a presumption). This ensures that one cannot just cheaply “clone” (make a “government-approved” unlicensed copy of) a Bell Iroquois for say, one-third the original price tag. I heard this from a medevac pilot during a bible study. He also claimed that a greedy congressman on a committee overseeing some government program for tilt-rotor development forced Boeing to change the original engine of the V-22 Osprey prototype to an already existing engine that his state produced even though the older turbo-shaft would force Boeing’s engineers to adjust the aircraft for a weight change and the latter engine’s performance not being as good as the specified original… Or am I wrong?

        • “change the original engine of the V-22 Osprey prototype to an already existing engine”
          This is not silly, consider that prototype engine can never enter production/don’t reach required number of horsepower/has too short life. For example many WWII-era soviet aeroplanes prototypes never enter mass production due to lack of proper engine when other has lower characteristic due to use of substitute engine; Soviet Union during WW2 has problems with high-power aircraft engine, examples:
          Shvetsov M-71 – 18-cylinder radial (2×9) engine giving from 1500 HP to 1850 HP (depend on version). First factory trials in 1939, but pass state factory as late as fall 1942. Never enter mass production. Application: Polikarpov I-185 fighter, Sukhoi Su-6 attack (proved be superior to Il-2, but can’t be produced due to lack of this engine), Sukhoi Su-8 attack, Lavochkin La-7 fighter (enter production – adopted for other engine)

          Petlaykov Pe-8 was produced in rather small number (93) when compared to US 4-engine bomber, however has many engine version due to lack of proper Mikulin AM-35 engine, which lead to different characteristic:
          Range with 2000kg bombs and full fuel tanks:
          Mikulin AM35-A – 3600km
          Charomsky M-30 or Charomsky M-40 (diesel) – 5460km
          Shvetsov M-82 – 5800km

          • And not only Soviet Union has aeroplanes which fail due to lack of engine: see Westland Whirlwind which enter production, however only 116 examples were build due to problems with RR Peregrine engine (redesign to other engines was considered not feasible)

          • Military and military procurement is about as far from Laissez-faire as it is possible to get.

            Crony-ist
            or crony cRapitalist would be better descriptions.

            There is actually a name for the siting of military industrial facilities in each and every political constituency – “political engineering”

            The way that this works is that any congress critter who ever even hints at criticism of a project which has run way over cost, over time and either has failed to deliver completely, or has way under delivered,

            isn’t only faced with accusations in his local newspapers of aiding and abetting enemies, terrorists, would be invaders (such as Grenada) and threatening defence, but of threatening jobs and livelihoods in his own constituency…

            Just to add to the list of aero engines which completely failled. The WW1 British ABC Dragonfly static radial – ordered before a prototype had even run, and supposed to be capable of over 200HP, the prototypes which did run, did so with their cylinder heads glowing red. Fortunately W O Bently was able to work his magic on the basic Clerget rotary radial design, with larger capacity and cast iron liners in aluminium alloy cylinders, he was able to both exceed the required HP, within weight and gyroscopic limits (actually less gyroscopic effects than the 130HP Clerget) and eliminate the cup washer type top piston ring required for thin wall steel cylinders, which had required other rotaries to undergo a full rebuild after every 12 hours of running!

            Rolls Royce Eagle 24 cylinder X layout. This was the engine which the AVRo Manchester was to use two of. Neither performed to expectation. Substitution of 4 merlins gave unexpected aerodynamic benefits and resulted in the Lancaster – a hugely successful aeroplane for a largely disastrous and counter productive strategy: terror bombing civillians.

            Multi row radials have always been a troublesome stop gap, until the next larger single row radial can be de-bugged and put into production. The longer crank usually results in resonance within what should have been the operating rev band. I forget which one of the WWii US radials had only two useable power settings, and needed to be revved up to them or changed between them as fast as possible due to resonance at anything other than those settings.

          • Hi, Keith :

            I think you meant to say “Rolls-Royce Vulture” in reference to the 24-cylinder X-configuration engine that proved such a disaster on the Avro Manchester of WWII fame ( or infamy, as the case may be ). The RR Eagle was a highly successful series of aero engines that was developed during WWI, and which saw extended service into the 1920’s.

            Speaking of Manchesters, a very good personal memoir which I would highly recommend for anyone interested in the early ( up until 1942 ) days of RAF Bomber Command during the Second World War is John Bushby’s “Gunner’s Moon” ( Ian Allan Ltd, 1972 / Futura Publications 1974-1975, ISBN 0 8600 7054 9 ). Bushby served as a gunner in 83 Squadron of 5 Group in first the Manchester, and later ( fortunately ) the Lancaster when the Squadron converted to the latter. He is one of the very few writers I have come across who has had real operational experience in the egg-shaped Frazer-Nash FN7 dorsal turret ( that’s “top turret” for American readers ) fitted to the Manchester, and who has written candidly about that turret from a user’s standpoint. This same type of turret, nick-named the “Botha” turret, was also fitted as standard equipment to the Short Sunderland III flying boat. What is equally fascinating and informative about “Gunner’s Moon” is that it traces Bushby’s career from humble beginnings as a volunteer “erk’ ( Aircraftsman or ground crew specialist ) with No. 601 ( County of London ) Fighter Squadron of the Auxiliary Air Force during the heady pre-war and early-war years, through assorted stints at, among others, No. I Course, Air Armament School, RAF Manby ( Vickers Wellingtons ), and No. 4 ( OTU ) Manchester Course, RAF Finningley / RAF Bircotes, and eventually on to 83 Squadron. In the process, one finds detailed and often undiscovered historical vignettes about the RAF and its personnel that can only be gleaned from someone who was there through it all.

          • Hi Earl,
            Well caught, it was indeed the Vulture.

            I know one gentleman who was a gunner in a Lancaster, and survived three tours of duty. Tail gunner!

            I think the statistical odds of survival are probably similar to jumping out at 30,000′ without a parachute

            He does get airside at airshows, and I think he got a look into the tail turret of the Canadian Lancaster when it was over, as well as the RAF one.

          • Hi, Keith :

            The gentleman in question is truly unique in that he is one of the very small handful of survivors from among his class or course. You probably already know all about what I am going to say, but I hope you will bear with me as I think it is important to share this information with other FW readers.

            If I remember correctly, standard RAF Bomber Command aircrew policy involved completion of a tour of 30 missions before one was entitled to a six-month screening ( break ), after which one had to complete another tour of 30 missions before being entitled to permanent screening. Alternatively, aircrew could elect to extend their first tour to a full 45 missions before being given permanent screening if they felt they could stand the strain.

            One thing that is not often brought up in most publications and accounts ( Bushby’s “Gunner’s Moon” is an exception ) is the fact that the aircrews who selected the former option had to serve as instructors in OTU’s and OCU’s during the six months’ screening, since they formed a valuable pool of hard-won operational experience that had to be imparted to the new aircrews. The problem with an OTU or OCU assignment was that one was saddled with a sprog ( green/inexperienced ) crew, and the casualty rate from flying accidents was often as high as in the operational squadrons. As a result, a lot of experienced aircrew who had survived the rigors of that first tour were killed or injureded during their time in the OTU’s / OCU’s — which completely belied the rest break they were supposed to be getting.

            Since the law of diminishing returns was painfully most relevant to any aircrew’s chances of survival as the number of missions flown accumulated, those who elected to take the latter course and fly a straight 45 missions were hardly better off.

            It has been calculated that the average casualty rate among Bomber Command aircrew throughout the war was about 4%. Obviously, there were missions where this rate was drastically higher ( as in the disastrous Nuremberg raid of November 30th/31st, 1944 ), and others where the rate was much lower. What the seemingly innocuous statistic of “only” 4% really meant was that, in theory, the entire original complement of aircrew in any squadron would be wiped out well before the initial 30-mission mark was reached. In practice, some crews were shot down on their first few missions while others were lost halfway through their tours, and so a small fortunate handful would survive to complete that first tour. The odds against survival then increased almost exponentially with additional missions or tours completed. That is what the hard, cold, inexorable arithmetic of a 4% caualty rate truly represented. Such was the cost, and such was the sacrifice.

            In that light, your acquaintance was incredibly lucky to have survived three tours. It also means that he probably volunteered for the third tour when he clearly didn’t have to, which says a great deal for his courage and fortitude, particularly since tail gunner casualty rates were higher than for other crew positions.

          • Oops. I meant laisse-faire as in “armchair warrior allows the guy who can supply stuff the cheapest to have the contract, even if the selected party has terrible quality control.”

  4. I can tell by your battered hands you’ve been doing a lot of gun-handling for this series!

    Great video. Fascinating how complicated MG feed mechanisms are.

  5. That slow motion footage shows a good amount of flexing where you had said the receivers would crack. Hanging the ammo can off of that spot couldn’t have helped.

  6. Ian,
    isn’t this a CMG-3, and not a CMG-2, like you stated in the headline – typo?
    You got my hopes high for a second CMG on auction at James D. Julia’s – not that I could bid on it in any way…

  7. Noticed the barrel retaining latch under recoil?.. It swings like a feeding chicken. A little more weak or broken spring and the barrel goes off during firing. Simply spring power for retaining of vital parts in service firearms should not be a subject to be depended upon.

  8. What was the switch at the top rear side of the pistol grip? Or did I miss something?

    With all the clever design touches–such as the dual-ended firing pin–I’m surprised barrel retention relied on one spring loaded latch. That could get exciting with wear or bad luck.

  9. Could you just put a new belt on if the on in Drum is empty, with the drum still attached? The gap between drum and feed slot looks like it
    Stephan

  10. Very, very Cool.

    Thankyou again Ian.

    Re the loading press case holder type extractor, Oerlikon becker type cannons and I guess if we are slack about our definitions, then the gibs down the side of a Vickers MG bolt face too.

    The bolt cam and locking pin looks like a far more efficeint manufacturing method to obtain the effect that required cams on the breech face of the barrel and the front of the bolt locking lugs on the FG42.

    Incidentally, does anyone know if the Lewis uses the same set up on its rear mounted bolt locking lugs?

    That receiver was certainly doing some flexing during the slow motion!

    despite the durability issues with this particular design, what a difference twenty to thirty years made between the Enfield EM2, with its machined from solid receiver shell and Colt’s electron beam welded fabrication of what look to have been rolled strips.

    • Wasn’t the Stoner’s price tag that made the Army sick? But then again, it was still better than some of the “recommendations” of the time. Armchair bureaucrats still seem to call the shots.

      [Optional material, I can’t think of a weapon of choice scenario right now… darn it all]
      Which of these seems best in terms of user-friendliness and reliability in the field far away from base?

      1. Stoner M63
      2. Kalashnikov family
      3. AR-15 family
      4. MAS-49
      5. Gewehr 98
      6. Type 99 long Rifle with monopod and anti-air sights
      7. Officer’s Nagant 1895
      8. Break action shotgun

      • Can’t speak for user friendliness, but the Nagant was described as ‘Doesn’t break and when it does you can fix it with a hammer.’ However, that particular description seems to sum up most Russian military design philosophy.

      • “2. Kalashnikov family”
        I assumed that you are thinking about PK machine gun.
        If you are interesting in infantry firearms of Soviet forces in Afghanistan 1979 – 1989 you should know PK well, however does you know that instead of PK other design was almost adopted – Nikitin-Sokolov ТКБ-521 machine gun?
        https://ru.wikipedia.org/wiki/Пулемёт_Никитина-Соколова
        It was not adopted but was basis for later big-bore NSV “Utyos” machine gun.

        “5. Gewehr 98” is not “user-friendliness” when considering disassembly procedure

  11. Keith,

    From photographs I have seen, it does not appear that the Lewis gun has a so-called “anti-preengagement shelf” in the bolt cam groove that would necessitate radii on the front of the locking lugs to kick it out of alignment with the cam pin.

    Admittedly, I have not handled one closely, but it is a subject of interest to me. The radii on the front of the locking lugs of the FG42 (and M1 Garand, M14, M60) also appear to work on the extraction phase, basically turning the op-rod and bolt into a differential screw mechanism having a large mechanical advantage for cartridge extraction.

    -Hound

    • Re the Garand and M14 extractor cam.

      I don’t know how much empirical basis there is for its usefulness. From a theoretical point of view, the gun is using the locking/unlocking cam to turn the linear motion of an already bent op rod into rotary motion of the bot which then uses a second cam (with all of the friction losses and clearences involved) to get – reciprocal motion.

      The American literature of the time makes big play about “primary extraction” which toggle lock (Maxim & vickers) and tilting lock/bolt (BAR, BREn & FAL) guns, and manual bolt actions have plenty of, and to an extent, so do guns with a seperate accelerator too, Browning and Lahti MGs.

      M T Kalashnikov, straightened out the Garand op rod, and put (much) more mass in the bolt carrier, and completely omitted the primary phase of extraction, and it works as well or better than any of the guns wth primary extraction (ok, hard chrome plating the chamber may help with this).

      Admittedly the 5.45mm ’74 case has a thickened rim compared to the 7.62, but that still represents a more elegant solution to the issue of extraction than using cams to turn reciprocal motion into rotary and back to reciprocal.

      Incidentally, looking at western popular assessments of the Soviet 5.45mm round when the first examples started coming out of Afghanistan in the early 1980s, and all the propaganda references about a bullet that was designed to tumble on impact…

      The guys were so busy propagandizing that they completely missed the point that what they were looking at was a beautifully engineered, light, Very Low Drag bullet, far superior to the then NATO 55 grain 5.56 loading, and arguably superior to the current loadings which require operating pressures of around 65,000 PSI to achieve the required performance from an M4.

      • I ponder this as well. Manufacturing is greatly complicated by the addition of helical locking lugs and the associated cams to provide for so-called “primary extraction.” I think it’s interesting that George Chinn, John Rocha, and Charles Balleisen all describe “primary extraction” as a positive design feature. The 1918 BAR patent states that the purpose of the acceleration/deceleration of the BAR’s bolt is eliminate high impact forces between the steel parts of the gun (although I would argue that the cartridge case is certainly a part of the gun, for a very short period of time, and subject to the same laws of physics). The true intent of those features may not have been fully disclosed in the patents, for all I know.

        I’m not sure I agree that the AK-47/AKM have eliminated the “primary extraction” in which the bolt is cammed away from the chamber. The PKM retains this feature – I measured it with my dial test indicator. I could not measure an AKM bolt’s relative movement, because the bolt shank is obscured by the op-rod. I would assume that the AK-47 has this also, given that it has the angled locking lugs and the same “bullet guide” that is provided the cam for the bolt to push itself away from the chamber.

        The M60 and M249 both have primary extraction, so I would assume that there was enough empirical evidence available to the designers post-WWII top include the complex cam geometry, although I have never been able to locate any sources for this. It’s possible that the helical nature of the lugs is simply to provide mechanical advantage for the bolt to cam a cartridge into the chamber, the components having axial interference with eachother (so called “crunch-up” or “crush-up”).

        It certainly is a fascinating subject.

        • Thanks Hound,
          Sometime after I typed the first reply, I had the “D’oh!” moment, that I’d not given the gun that this post is about, as an example of no primary extraction.

          But then we have the other example of the AR10 and AR15, where the reaction to the gas accelerating the bolt carrier for the unlocking phase, tends to relieve some of the normal stress on the locking surfaces (not a bad thing), and to push forward against the empty case, rather than having a primary extraction phase.

          My personal guess is that actions with springy locking systems and or poor control of headspace, are going to give the most problems with extraction, but less battering of locking surfaces, as the cartridge case stretching absorbs some of the backthrust (Vaughn, “rifle accuracy facts” has a graph of measured case head backthrust decreasing as headspace was increased on a .270 Win chambered bolt action, I think backthrust went from 8,000 pounds to about 2,000), but then the elastic relaxation of the springy locking system shoves the now stretched case hard into the chamber when gas pressure drops – a bit like knocking a morse tapered centre in.

          • I will have to read that book. I have never heard of it – but then, there are many things I have never heard of.

            I have to wonder if the intent of “crunch-up,” or actually forcefully chambering a cartridge case in a chamber that is actually .005″-.010″ too short, actually allows the case to expand axially and relax in the radial direction upon unlocking, away from the chamber walls, and that THAT is the intent of the helical locking lugs – simply to achieve an initial compression on the cartridge case. Perhaps the supposed differential screw mechanism actually has nothing to do with anything, but is rather just a convenient way to kick the “anti-preengagement shelf” out of alignment with the cam stud. This document states that a .30-06 case sees an additional radial expansion after pressure has dropped off in the case, due to Poisson’s ratio:
            http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0701178

            It is too bad we can’t pick any of these designer’s brains, since most of them are dead.

          • Hi Hound and Earl,

            Sorry for the long time in replying further to this.

            I’ve read and digested the Springfield extraction trials paper.

            Their idea of reducing extraction forces by increasing headspace may have limited truth.

            However, the experience of fire forming cartridges that have the shoulder blown out or blown forward, suggests that the opposite tends to happen, the poisson spring back tends to occur in the length of the cartridge, rather than diameter and circumference.

            For a citation to that effect, see Ackley hand book for shooters and reloaders, vol 1,

            Iirc, one place he describes the effect is on the the page where he covers the .25 06 and its “improved” kittens.

          • D’oh no edit feature.
            One explanation for the reduced extraction force with the excess head space chamber, is simply the increased chamber volume reducing pressure, without increasing the side clearance.

          • Keith,

            My contention is that the ideal headspace in any locked-breech weapon would be zero (cartridge has perfect fit in chamber) or slightly negative (cartridge is smashed into chamber). I think the Springfield Rifle chamber arrives at that conclusion. George Chinn also mentions (p229, The Machine Gun Volume III) that, in reference to the “Shirgun” that external lubrication on ammunition can be eliminated if the headspace can be held sufficiently tight. The particular weapon he is discussing has a locking mechanism that adapts to the headspace of any particular cartridge, giving what he calls “zero headspace.”

            I have never read any of Ackley’s stuff – I will have to get that book. The initial volume of the chamber undoubtedly matters as to its influence on peak pressure, as well as the position of the throat relative to the bullet’s ogive.

      • I agree regarding the design and ballistics of the 5.45mm x 39 round. I have an early-model Waffen Werks AK-74 built on a new Bulgarian mil-spec parts kit, and both the rifle and its ammunition are superb, to say the least.

        Nathaniel F., who is a very knowledgeable and fluent long-time contributor with excellent writing skills at The Firearm Blog ( http://www.thefirearmblog.com ) — to which Ian McCollum has contributed in no small measure from time to time — has said pretty much the same thing about this cartridge in detail. And that’s coming from someone who has in the past openly acknowledged his preference for the 5.56mm x 45 cartridge.

  12. 7.62mm minigun bolts have integral extractors like the CMG-3 shown in the video. The Colt designers were probably not ignorant of the benefits of that type of extractor.

  13. Hard to believe that such a well thought out, clever design was around at the same time as the poorly thought out M60. I’m sure the CMG 2/3 would have been much easier to lug around a jungle, too.

  14. Cherndog: re: “6. Type 99 long Rifle with monopod and anti-air sights.” Got one with the original web sling and dust cover as well as a carbine model and a “Booby-Trap” model with a cast iron action and a Black Powder Only model designed to train troops using wooden bullets.

  15. “Mo’ betta Sho-sho!” Very interesting and informative video. The SEALS are quite unusual, and I’ve seen a particular small unit set up where a single squad employed no less than *four* lightened M60 LMGs as shoulder fired weapons.

    Looking over Ian’s excellent video, I’m almost inclined to think this would be the LMG version of the TRW “low maintenance rifle” concept, no?

    As far as the charging handle and the rear pistol grip being one and the same, is the very first example of that the BSA prototype of the BESAL LMG? I know the Czechs put that on the VZ52 LMG, which could use either box magazines like the Bren, or belt feed.

  16. Most impressive American designed MG as far as I can tell; perhaps eclipsing less than lustre M249.

    Greeting to my friends and colleagues in FW discussion after some leave of absence! Great job Ian, as usual for you!

      • Thank you Earl!

        Yes, everything is ok on my side as much as I hope is on yours. I spent couple of weeks in EU, specifically on Italo-Austrian frontier from WW1, retracing paths of my grand-fathers. It was fascinating experience. Other than that, he countryside is gorgeous and locals are kind.

        I also read studious considerations on alternative head space arrangements by our valued friends. There is never enough of, one can say he knows. Thanks for it all!

        • Glad to hear it, Denny! Your journey must have been both spiritually and historically edifying, enabling you to connect in the sort of unique and tangible ( or intangible but recognizable ) way that we all wish for at some point in our lives. I find that as I get older, the urge to re-connect with the small but meaningful relationships and memories, people and places grows stronger over time.

          It would be wonderful to hear about your journey, as and when you choose to share it. If not, your privacy is to be respected without any exceptions.

  17. A couple of corrections to my Sept. 24, 2015 / 11:35 a.m. post :

    1. Line 17 from the top — “Injured” instead of “injureded”

    2. Line 5 from the bottom — “Casualty instead of “caualty”

    Apologies to all for the typographical errors.

  18. The two-ended firing pin was, I presume, borrowed from the Mendoza LMG. Speaking of which, do you have an episode on that one? Yes, I know, it’s in no way forgotten, but after all, who here has ever handled one?

  19. Ian,

    It’s absolutely phenomenal how many machine guns that really were amazing and very innovative were developed in the era from 1944-1980 in the west. And how few made it into production, or even have any significant technical information available on them.

    Also the scaling of MG’s was a major theme in this time period. Cmg 2/3 xm235/248 (5.56 6mm SAW 7.62 NATO versions were all built and tested. Like the hk21/23 all 3 chamberings worked off the same receiver with the appropriate subassemblies swappable by an end user in the field.

    Speaking of the xm248, which manual DVD is the XM248 technical manual on? Or is there a way to purchase the manual singly as a PDF download?

    Also would it be the library of congress or some office in the DOD that I would need to write to request copies of stAndard part drawings for the M231 port firing weapon? I specifically want to request the necessary pages to get the specifications dimensions tolerances and materials call outs for the following parts

    1. Buffer tube end cap
    2. Polymer bumper stop
    3. Buffer guide rod
    4. All 3 buffer springs (single most critical)
    5. Striker and firing pin (if firing pin is not standard usgi spec)
    6. Buffer latch plate
    7. Barrel profile
    8. Buffer tube

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