The Brazilian Uru SMG: A Study in Simplicity

The Uru, named for a tropical bird, is a Brazilian 9mm submachine gun made from 1977 until 1985 and used by Brazilian military and police forces. What makes it interesting is the designer’s focus on simplicity – the gun has just 17 parts, and basically no screws or pins (except the bolt holding the pistol grip on). The trigger mechanism and drop safety are quite interesting to see!

39 Comments

  1. What impresses me is how Brazilians managed, in their rather humble circumstances, to cover their police/ military equipment needs domestically. This is not exactly pretty gun, but why it should be? It is simple and functional – I give them thumb up.

    Btw, I would not worry about pronunciation of foreign names; not a big deal. Attempt itself is praiseworthy.

    • Their previous “domestic” standard SMG, the INA M953, was a licensed copy of the Madsen M50;

      https://en.wikipedia.org/wiki/INA_Model_953

      The only major difference was that due to MAP, the standard Brazilian army sidearm at the time was the Colt 1911, so the M953 was duly chambered for .45 ACP instead of 9 x 19mm just to keep things simple.

      In fact, to judge from the Uru, the “KISS” principle seems to be pretty popular with the military and police down there. Like M953, the Uru is an example of “everything you need and nothing you don’t” in a submachine gun design.

      Speaking of simple SMGS, “improvised” ones show up frequently in the hands of criminals in Brazil;

      http://www.thefirearmblog.com/blog/2014/01/22/common-illicitly-homemade-submachine-guns-brazil/

      The majority seem to be simplified copies of the Uru. I suspect minus the more important safety equipment like the anti-bounce-fire block.

      cheers

      eon

    • “Brazilians managed, in their rather humble circumstances, to cover their police/ military equipment needs domestically”
      In 1980s, there was Main Battle Tank designed in Brasilia, namely Osório:
      http://www.tanks-encyclopedia.com/coldwar/Brazil/osorio-ee-t1
      it was own design (not knock-off of existing vehicle), which managed to go to prototype stage and didn’t go into production, due to political reason which caused potential buyer to abandon that idea.

  2. I am impressed with the “drop safety”. The cost must have been quite low also. The only thing I didn’t like was the removable butt stock. It is probably more stable than a folding or sliding type but would be quickly lost.
    Jim

    • The Sten MK II and III also had a non-folding, removable buttstock. Like them, the Uru can be taken down into a very small “package” if concealment is a prime desideratum.

      The improvised Uru copies noted above rarely have any buttstocks, period. They are generally fired like an MP5K PDW or etc., either one-handed or with that nice, sturdy magazine housing forming a very firm foregrip.

      Note that unlike the M3, MP40, etc., that long housing allows you to grip the magazine firmly without “canting” or bending it in any direction, which reduces the chances of a jam or misfeed.

      The Argentine Halcon and MEMS SMG series used a similar setup;

      http://www.forgottenweapons.com/argentine-halcon-smg-family/

      In fact, there’s a distinct “family resemblance” between the Halcons and the Uru.

      cheers

      eon

      • “Sten MK (…) III also had a non-folding, removable buttstock. Like them, the Uru can be taken down into a very small “package” if concealment is a prime desideratum.”
        Though in case of dire need of opening fire (without installing stock) Uru should work quite good – in case of STEN Mk. III I am not sure – it is even possible? if yes – does anyone attempt to do so? if yes – what was result?

        • The Sten MK II can be broken down into stock, barrel, and receiver groups, with the receiver being the longest bit at 31.5cm (12″);

          http://thehomegunsmith.com/pdf/Stengunplans.pdf

          On the MK III, only the stock comes off, but the one-piece receiver with semi-permanently mounted barrel is only about 46cm (16″) long;

          http://www.koreanwaronline.com/history/Sten/1.pdf

          So either one could be fairly easily concealed when broken down.

          I don’t believe attempting to fire either one minus the stock was advisable, as the stock included what passed for the actual “pistol grip”. Some “underground-made” Sten copies solved this problem by substituting a simple pistol grip attached to the rear plate instead of the full rifle-type stock.

          cheers

          eon

          • “Some “underground-made” Sten copies solved this problem by substituting a simple pistol grip attached to the rear plate”
            Polish resistance used own STEN-like weapon called BŁYSKAWICA
            http://modernfirearms.net/smg/pl/blyskawica-e.html
            notice that they chose to make it more similar to MP38 ergonomic-wise (fixed pistol grip, folding stock, magazine sticking downwards)

    • That last improved version actually had a side folding stock, but it looked kinda awkward when attached to the end, kinda like its frankengunned, like seeing stg44 with underfolder stock…

  3. Neat stuff. One small correction, I think “Mtr.” is likely an abbreviation for “metralhadora” (“machine gun” in Portuguese.) It would not be surprising if that abbreviation was also used for a submachine gun as well since in Portuguese that’s a “metralhadora de mão” or “hand machine gun.”

    • “It would not be surprising if that abbreviation was also used for a submachine gun as well since in Portuguese that’s a “metralhadora de mão” or “hand machine gun.”

      Don’t think so. In current Portuguese, submachine gun is “pistola metralhadora”, at least in Portugal. In Brasil, the current designation is “subfusil”.

        • Bem vindo!

          I was surprised when I was in north eastern Brazil that Erma-type SMGs and Steyr Solothurns were already in use by the early 1930s during the suppression of the cangaçeiros like Lampião and so on. I think that just might be the earliest use of SMGs any place in Latin America, although the U.S. Marines had some against Augusto Sandino’s “banditti” in the late 1920s, and I think some were used in the Chaco War in the 1930s by Bolivian and Paraguayan armed forces.

          As for names of SMGs in the Lusophone vs. Anglophone, Francophone, etc. worlds, I do believe Portugal used to use pistola-metralhadora.
          Spain, and I do believe Argentina preferred sub-fusil, but then again the “PAM” series in the latter show “pistola-ametralladora” like German “maschinenpistole.”
          France has miraillette or pistolet mitrailleur. The Brits had “Tomm[‘s?] gun” and officially machine carbine before going eith the U.S. “SMG.”
          Italy, pistola mitragliatrice, unless I’m mistaken.

          Portugal’s very first SMG was a 7.63mm caliber Steyr Solothurn. Later, the 9mm Steyr was the 9mm m/942 [model of 1942 during the quai-fascist Estado Novo.]
          The 9mm Sten was the PM 9mm m/942.
          The FBP/ Fábrica Braço de Prata 9mm m/948 that combined elements of the U.S. M3 and the German MP40 “Schmeisser” (I know, really the “Vollmer!”).
          A few Madsen m/50s, known as m/955s in he “Ultramar” colonies.
          The Belgian Vigneron as the 9mm m/961 from nearby Belgian Congo/ Congo was used in the colonial wars in Angola and probably Moçambique too… Not sure about Guinea-Bissau.
          The Uzi 9mm was officially adopted, also as the m/961 I believe. It was used by officers and so on.

          After the 1974 Revolution, MP5s were adopted, and the so-called “Lusa” using the same trigger-mechanism as the G3 rifles was tested, although I do not think it was adopted. Perhaps someone knows more about that.

          • “Italy, pistola mitragliatrice, unless I’m mistaken.”
            When? For example well-known sub-machine gun made by Beretta was designated MAB 38 which mean Moschetto Automatico Beretta Modello 1938

          • “Italy, pistola mitragliatrice, unless I’m mistaken.”
            Judging from photos in Italiano wikipedia:
            Mitra (query: Mitra (arma)) is sub-machine gun
            Pistola mitragliatrice is machine pistol (for example Beretta 93R)

          • “someone knows more about that”
            Sub-machine gun LUSA A2 (Portugal)
            http://www.dogswar.ru/strelkovoe-oryjie/pistolety-pylemety/5330-pistolet-pylemet-lus.html
            Sub-machine gun Lusa A2 was developed in 1983 by Portuguese company INDEP as replacement for early FBP [that probably mean FBP m/948]. It is named after Lusitânia, one of ancient Roman provinces, part of this province is where Portugal today is. Initially it was devised for military, it was found also suitable for law enforcement and bodyguards. Some construction features were borrowed from G3 rifle, which was at that time license-produced in Portugal.
            It has inspiration from:
            – MP5 (general layout)
            – Uzi (barrel change)
            – G3 (grip, safety-selector)
            In 2004 INDEP sold documentation to company LUSA USA, which produced this design in full-auto and semi-auto (for civil market)

      • In Brasil they speak portuguese, so Matthew explained it very right. Subfusil is in spanish.

        The only nuisance with that revolutionary simple one piece trigger-sear-disconnector is that you always have a finger slap on semi, since bolt hits that back sear catch before it springs up again due to your finger pressure on trigger.
        Btw. congratulations to Ian for a really good explanation of the whole system !

        There was an improved version of the Uru in the late 80s to 90s, that added some minor changes like forward wood grip and regular wound sear spring instead of that steel strip,and some other, but it was never made anywhere in numbers like the original. Also, some original models had a grip safety.
        According to R. Olive, good old brave Olympio showcased the effectiveness of the trusty bolt safety multiple times; with gun loaded and his palm covering the muzzle, while hitting with it on the hard surface !

        Apparently there was an affair that some american firm made some unlicensed copies, slightly cosmetically different, named Saco 6something number, but info on it is very scarce on the internet; one of that forgotten weapon mysteries I hope we will uncover one day.

        Imho this could have been very (cost)sucessful smg had it not came after the golden age of smgs passed, for example if it was created during or after ww2; easy to see how much simpler even compared to Sten it is.
        For it, I see its creator certainly in the Pantheon of one of the more (or even most) talented gun designers.

  4. The recoil spring, its slot in the bolt, lozenge shaped tab and even the shape of the bolt reminded me of a Ruger Mk II.

    Looks like the sort of thing the gunsmiths in Peshawar would have been able to copy with great ease, although a 9mm subgun isn’t probably a lot of use in the mountains of the Hindu Kush, range-wise.

    • @Matt
      Folks from D.A.Khel are that much talented and skilled that they can reproduce you any type of firearm, and looking from afar you would not see a difference ! Uru would they churn out in one lazy saturday afternoon.

      Only with these modern plastic g36,glock etc. ones would be problematic, but I wouldnt bet that they are not reverse engineering that technology these days, and in a few years would master that also. After all, its a place where for generations main business and occupation to large number of people is making, thinking about and selling only guns.

  5. Wow. A whole selective fire trigger group consisting only of two moving parts (selector plus the trigger/sear part) and a leaf spring. This is genius. I also like how the attach the upper to the lower receiver without welding. Whoever made this was clever and talented.

    • Name was Olympio Vieira de Mello.
      Unfortunately he passed away back in the 80s, probably due to his heavy smoking habit.

      There is some more info in online article on small arms review, as well as a few good photos of its author.
      This is not his only brainchild, he worked on some GPMG and some other guns also, but surely is the most known and commercially made.

      • Hi, Storm :

        I think the GPMG you are referring to may have been the Mekanika Uirapuru, chambered in 7.62mm x 51 NATO. From what I have seen published, the design emphasis was, like the Uru, on simplicity and reliability.

  6. One difference in Portuguese military terms between Brasil and Portugal is the term for military rifle:

    “Fuzil” or fusil in Brazil.
    “Espingarda” in Portugal.

  7. Dang. Just 17 parts?! That’s not many! This might just be one of the simplest, no?

    Muito obrigado Ian! Very interesting.

      • Ah, yes. True that! See the comments above about the, erm, “favela-expedient” home workshop SMGs that turn up in Brazil from time to time!

        Sure wish I could find out more info on the French prototype MAC 48-2, although it did have a grip safety a bit like the Israeli/Belgian/German Uzi 9mm and dual triggers like the Marengoni Italian SMGs…Still reliant on the MP40 magazines, I believe.
        Perhaps one or another of the Russian-language sites has mention of it?

  8. An incredibly simple and effective design that works. The Uru also appears to be sturdily built to withstand long-term hard use. It would be great if Mekanika or someone else started making the Uru again in a civil export model.

    A cyclic rate of fire of about 400-500 rds./min. might have been more practical and certainly more controllable, though.

    As to the comment about magazine reliability and functionality, I’m not quite sure if the two-row design tapering to a single-row feed at the top is an issue at all. Most modern semi-automatic combat pistols, eg., CANIK-55 TP9, CZ75 SP-01 and SP-09 and AREX REX Zero, use large-capacity magazines with the same type of configuration and have proven to be completely reliable.

    • Pretty sure that pistols do not have constant 750 rounds per second, 30 in magazine.
      But of course that is not a huge “flaw”, I suspect it used that style of mag for not needing the feedramp (like in double feed where you need it), thus eliminating another part from gun to be made, making barrel simpler.

      Lower rate would be possible, but then you would have full size smg, and I suppose this was going for the compactness, but again, not extreme, like in ingram, that the gun became practically useless due to the huge rof.
      As for the brazils improvised guns that seem to be extremely popular in favelas, I believe that the craft and tradition of it started way before Uru was manufactured, so it cannot be called a main influence. Though some of the examples mimicked its lower and upper receivers fixing method, but that was practically all of similarity; not one copied the trigger system (which would be not easy, as the original gun is, I suppose prety much unobtainable for our common favela gunsmith). Lot of these guns are seen cofiscated by their police almost in a weekly basis, but I believe they are seldom used, and are probably extremely prone to jam, as they mostly make their own mags too, and more often than not in ridiculous lengths, like you want to stuff 40 rounds single stack.

      • Thanks very much for sharing your thoughts — much appreciated. The point I was making was that service magazines of a two-row ( double-stack ) tapering into single-row ( single-stack ) feed design have proven to be extremely reliable, so I’m not sure why Ian made the comment in the video that this particular application in the Uru would be less than that, regardless of rate of fire or magazine capacity.

        Interesting information about the improvised firearms from favela gunsmiths, though. Good point about the ridiculously lengthy 40-round single-stack magazines — you could probably just as easily club your adversary to death with one of them as shoot him :). My guess is that they make magazines like this based on the ( wrongly ) perceived perception of providing added firepower, plus the visual intimidation factor.

  9. Yep, I suppose main function of these guns is the intimidation of the probably mostly unarmed advesaries (which could be people they rob?),in that case the fact will gun work or not work in the critical moment is not that relevant to the users, but again can not be neglected as I suppose they are not sold for few bucks, but for a substantiable sums of money, thus leading to great supply and motivation of these favela gunsmiths wanting to earn some money any way they can.

  10. Another amazing post, I really enjoy your explanations, but the Uru wasn´t never adopted by brasilian armed forces.
    Brazilian armed forces was use Beretta/Taurus MT-12 during 70’s until 90’s
    Many thanks!

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