Slow Motion: Scotti Model X

The Scotti Model X (the X standing for the 10th year of the Italian Fascist era, or 1932) was one of a bunch of semiauto rifles tested by the Italian military during the late 1920s and early 1930s. The Scotti entry into these competitions was chambered for the 6.5mm Carcano cartridge and used standard 6-round clips, identical to the Carcano bolt action rifles. It also used sights basically identical to Carcano rifle sights. Where it was rather unusual was its open-bolt action, which is typically only used in machine guns.

Open bolt means that when the rifle is ready to fire, the bolt is locked all the way back. Upon pulling the trigger, the bolt moves forward, picking up a cartridge, chambering it, firing it by means of a fixed firing pin, and then extracting and ejecting the spent case and locking open again, ready for another shot. This system can be used with either locked or blowback actions, and the Scotti X uses a two-lug rotating bolt to lock during firing.

I will have a full video on the Scotti Model X coming later, in which I will address some issues like the difficulty of shooting accurately with an open-bolt rifle and the apparent need for lubricated ammunition in both examples of the gun that I have fired.

47 Comments

  1. Nice gun, looks well made, excellent presentation on your part Ian.
    Wonder what the German’s thought of it, assuming they were also watching the test?
    Always have to ask…what would one sell for in today’s market and how many are out there?
    Thanks
    Regards
    Pat

    • About 250 were made, all of them in 1933 as far as I can tell. Market price seems to be $6k-$7k, because not many got into the US – they would have to have survived troop trials and all of WWII before getting noticed by a US soldier as a souvenir. I am aware of about 10 in the States these days, although I’m sure there are at least a few more.

  2. That open bolt would have allowed a lot of sand into the action in the desert, I doubt it would have proved very reliable under adverse conditions.

  3. An open bolt semi auto rifle,, eek where to begin on the bad ideas in this weapon?

    First up, Accuracy wont be great because of all the movement just prior to firing.

    second, as already mentioned the whole top of the action is open to the elements, never mind dust what about rain and mud, foliage and body parts?

    Finally that big ass bolt handle flying back and forth,, yup not a gun for left handers–and tactically that means shooting around cover to your right means you will have to expose more of yourself as a target.

    I think at the very least a sliding dust cover and an unlocked cocking handle would be my first requirements on this rifle.

    By the way cracking vid Ian.

    • Open-bolt are mainly found in machine guns (“true” machine gun like Lewis gun as well sub-machine gun like PPSh), obviously accuracy of single shot is not so important in this design, but there existed open-bolt designs considered to be reliable enough (see for example BAR 1918), so the reliability issue is arguable.
      Also note Thompson Autorifle which was considered alongside Garand and Pedersen rifle as a future self-loading rifle.

      We must remember that in 1930s, tested and wide adopted self-loading military rifles didn’t exist. So designer incorporated solutions of then-known working sub-machine guns and machine guns.

  4. Interesting, but somehow pointless design exercise. What does it save or improve upon? Nothing of what I see. Thanks for video.

    • В.Е. Маркевич in Ручное огнестрельное оружие states that Scotti automatic rifle was rebuild Mannlicher-Carcano 1891 rifle. Weapon mass: 4.050kg, practical rate of fire: 40-50 rpm. He also mention that Scotti produced, for Italian Navy, automatic rifle with metal alloy stock, it consist of Aluminium, Magnesium and Silicium, which give lighter mass (density) than wooden stock, painted with camouflage, also Mannlicher-Carcano 1891 with stock from this material were produced. These weapon were tested in Italian Fleet but it result remains unknown to В.Е. Маркевич. [I would bet that this alloy maybe prone to corrosion, considering that Elektron alloy (Al-Mg-alloy) is prone to it]
      Similar to other repeating-rifle to self-loading rifle conversion it proved be unreliable.

      • A.B.Zhuk also introduced this model in his book “Vintovky i Avtomaty” and implies that it was also in caliber 7.92 Mauser, part of 6.5 Carcano. He just briefly describes method of operation, no details of service/development history.

    • Ok, but “save or improve upon” what? It’s a design of 1932. Years ahead than the adoption of the SVT 40 and the Garand, that anyway did come, the first after the higly unsuccessful AVS 36 and a redesign over the SVT 38, and the second after a redesign of the gas system, to be successful designs.

  5. I’ve had a long fascination with that open-bolt (full auto only, I think) 5.56 thing with the side-feed M16 mag that the normally high-tech satellite company TRW did as a side project for third-world countries looking for a low-cost local-made alternative to the 16. Really neat weapon that apparently was designed to fill a niche in the market that didn’t exist….

      • Hey, Ian, did you ever do an article on the Cannone-Mitragliera da 20/77 (Scotti)? It is probably “forgotten” compared to the Breda 35.

        • There are plenty of autocannon caliber weapons which are pretty obscure, but I think Ian mainly concentrates mainly on small arms and machine guns. That said, I wouldn’t mind an article about the 20mm Scotti AA gun.

          The funny thing about the Scotti is that many sources claim that it was not as effective as the Breda 35, but it fired exactly the same ammunition at almost the same muzzle velocity. Dispersion was said to be higher, but for AA use that is not necessarily a bad thing. SO I wonder what the references to “inferior performance” actually refer to. Shooting at ground targets in the desert at long range? The Breda was used a lot for that by both the Italians and the British (who captured a fair amount of them), so perhaps that really is the explanation.

          • “I wonder what the references to “inferior performance” actually refer to.”
            It has only been written in Chris Bishop’s “The Encyclopedia of Weapons of World War II”, and, since there aren’t many sources in English about that weapon, the statement (made only by confronting the muzzle speed of the projectiles, that was slightly inferior in the Scotti, due to the less “locked” action) became gospel. The Scotti was “inferior”.
            Curiously George M. Chinn (“The Machine Gun. History, Evolution, and Development of Manual, Automatic, and Airborne Repeating Weapons”) highly regarded the weapon, and dedicated to it a longer article than that on the Breda design.

  6. I suspect that by that time there might be a serious concern about rapid heating barrels and “cook-offs” in that novel semiauto rifles.

  7. Very nice looking compact rifle, if it was closed bolt it would be worth looking at, but open bolt is just a huge fail.

  8. I have seen a General Arrangement Drawing of the Scotti; the acion is a modification of the Mannlicher M95 straight Pull bolt, with the firing pin on the Bolt carrier ( like the Lewis Gun) The Gas Piston Pushes the cammed Bolt carrier back, twisting the Lugs (Bolt Head),out of engagement and Backwards. There is little delay, so the cases should be Lubed ( 6,5 Carcano cases were “coated” with something like wax, if one looks at a lot of Surplus M91 ammo still around.) Otherwise that old bugbear of many Italian Guns, separated head, will make itself felt…But Not “cook-offs” (Bolt stays open on Hot empty chamber).

    The “six-round Clip” mag fits with the “economy of ammo” Wooden heads opinion of the day (Not Just in Italy), but it did have a Practical Logistic Purposes…same type of ammo for all Soldiers (Bolt action and SA), and the idea was to issue the Scotti to only selected squad members, not a Universal Issue.

    The Design also had some Fragility Problems (as it seems only 250 were made?) And since it resembles outwardly an M91 (same fitting and general dimensions) it is usually found in the USA “by chance”, being mistaken as an ordinary M91 Long rifle. Of course, the “Converted Carcano” statement by Markievich ( English rendition) is partly true, they used the M91 Barrel and sights, Stock and fittings, TG-Magazine body, and some trigger Parts; the only totally New Part was the Receiver- Bolt Action, and Gas tu8be and carrier.

    Since the “Russkis” consider the Barrel to be “the Ordnance”, then Changing the Receiver out, was simply a “Modification” of the Original M91 Rifle.

    Scotti Guns (Both SA Rifle and Later, Aircraft Cannon) were built by the Isotta-Fraschini (Racing Car/Touring Car) Company, so Precision Manufacture was assured…maybe Too Much precision, for the Vagaries of the Battlefield (ie, North Africa, the Steppes).

    Would really like to have one, but 1996 makes it next to impossible Down Under.

    Doc AV

    • Yeah, too much precision. To be fair, the Scotti anti-air cannon was easier to build than the Breda 35 and it was a much lighter load to carry, despite its inferior performance compared to the Breda. As for the Scotti rifle, I’m disappointed that better development wasn’t carried out (from a technical view-point, not a political one, since the Fascists weren’t considered the best room mates). Having seen the Mauser 1898 short-recoil operated rifle patent, I think the Scotti would be cheaper to build and less likely to cost you an eye during a malfunction… or am I wrong?

    • Is a little unfair to describe the Scotti action as “a modification of the Mannlicher M95 straight Pull bolt, with the firing pin on the Bolt carrier”. The two actions are profundly different. The Steyr Manlicher like most rifles of its days, had two loking lugs that engaged int 90°, or near, slots (Like a Mauser or a Carcano). The bolt body had internal spiral-shaped ribs, with matching spiral-shaped cuts in the tail of the bolt head. These ribs and cuts forced the bolt head to rotate on the pull of the bolt body, locking and unlocking the action. So in a M95, when you pull the charging handle, the bolt head first rotates without retreat until the lugs disengage from the slots, and then is pulled back by the bolt body. Without the bolt body, but with the bolt head in the correct position, the M95 action is still locked, cause the recoil of the cartridge cannot rotate the bolt head.
      In the Scotti Action the lugs are engaged in 45° helicoidal slots, so the action is locked only as long as the carrier prevent the bolt head to rotate back when the cartridge is fired.
      This, on the one hand makes that the weapon will work in the way it works, infact the Scotti weapons are gas unlocked, but recoil operated. On the other, requires a far lower level of precision machining in making the bolts, and that’s evident confronting the two. Despite being 40 years older, the M95 bolt is a piece of fine mechanics compared to the Scotti one.

  9. Anyone have any insight into why virtually all Italian semi and full auto weapons have only single stage extraction? Seems like they had no idea their weapons could not be made as reliable as the two-stage extraction designs were. It obviously wasn’t a complicated manufacturing issue as witnessed by the overly complex weapons they did produce, so why the huge blind spot in their designs?

    • I’ve heard of these since I was in grade school, but never knew they operated from the open bolt. That’s obviously dubious for a semi-auto shoulder weapon, even more so in one in which the bolt flies back toward the firer’s face.

    • The Japanese had the same issues with lubricated ammunition, although a lot of that was supposedly due to an inability to hold required machining tolerances. This was also the downfall of most Japanese inline aircraft engines.

      • Which raises some interesting questions as to whether Japan would have lost that disadvantage if they’d paid more attention to the ammo when Pederson was trying to sell his rifle, or hadn’t he come up with the coating by then? I imaginge it would have had applications in other guns that required lubed ammo.

        • Given all of Japan’s other industrial shortcomings, I have grave doubts that they could have come up with a drive lube coating which both worked, and was capable of being produced in the required quality and quantity.

          As it was, they were producing UNcoated:
          6.5x50mmSR
          7.7x58mmSR
          7.7x58mm
          .303 British
          7.92x57mm Mauser

          I don’t seem them successfully adding another industrial process in addition to all of that.

    • I don’t really know, since I’m a casual viewer. Is single stage extraction something along the lines of “extractor pulls cartridge casing out of chamber and rams the rim against a fixed ejector which then causes the casing to bounce away?”

      Please correct the assumption if I’m wrong.

      • Single stage extraction is what you get in a blowback semi-auto pistol or SMG. The pressures are low and transitory enough that the case rebounds enough so that it’s no longer adhering to the chamber walls when the action opens.

        The most elementary example of two stage extraction is a turning bolt rifle like a Mauser or Enfield, where lifting the bolt handle loosens the empty case in the chamber prior to it being extracted by retracting the bolt handle.

        Rotating bolt semi-auto rifles, like the Garand, M-14, Kalashnikov, etc. have that initial extraction which prevents torn case heads and stuck cases.

    • The Breda SAFAT had an accelerator, and infact was known as an absolutely reliable weapon, extraction seemed to not being a problem for the gas-operated Breda too (Breda PG, 8mm Breda 37, 13mm Breda 31, 20mm Breda 35, 37mm Breda 37/54) all higly regarded weapons, and it not seemed to be a problem for the rifle that finally won the competition VS the Mod.X and the Breda PG, the Armaguerra 39. The only weapons that really suffered from extracion problems were two recoil-operated, short barrel recoil, weapons. The FIAT Revelli 14-35 and the Breda 30, that suffered from the abrupt separation of the bolt from the barrel at the end of the short recoil.The first was a relic of WWI, and the second was adopted first than the accelerator of the SAFAT (anoter recoil operated MG) solved the problem.

  10. As I understand it most modern arms use a two step extraction process where the first step is to use the compound leverage of the bolt mechanism to break the friction seal between the expanded brass casing and the steel chamber wall. There is usually some residual pressure in the barrel during this time but not enough to matter. Then the second step is the extractor removing the case for ejection. In a manual bolt action arm the leverage comes from raising the bolt handle before it is pulled back, you can see the bolt retract slightly during this phase using the camming action of the locking lugs. In a self loader the primary extraction usually comes from the bolt rotating or otherwise unlocking in some way, providing that same slight retraction with some mechanical advantage. The AR that I’m most familiar with uses the rotation of the bolt to break the friction of the case in the chamber, and in fact a rough or dirty chamber will show as leaving a rotational ejector mark on the case head. Most Italian designs did not have any primary extraction and only had the extractor doing all the work. This necessitated lubricated cases and very clean weapons, neither of which can be counted on on the battlefield. Combat reliability suffered accordingly by many accounts.

    • Oh, so that’s what you meant. I suppose the Italians didn’t realize that rotating the cartridge casing would be one way to get it to unstick itself from the chamber wall. Apparently, they didn’t see that it happened in the Carcano bolt-cycle. The blind spot is probably the issue of Fascists killing everyone who didn’t agree with them and most of the best engineers didn’t want to lose their heads.

    • Rotational movement of case inside an AR15 firing chamber is really interesting and new
      for me. Without a cammed backward traction, or clamped oppositely located dual extractors, what can cause a case head to rotate inside a high pressure contained chamber. However, Case head at instant of firing in an AR15 chamber, has equal powered
      pressures at inside of case and at inside of bolt carrier by cause of rifle’s in line piston system. But can solely this enables to rotate the case freely with sole hold of large extractor claw. The ressistance coming from the spring forced forward push of ejector may be discarded by cause of weakness of springs under inertia, but this also is gradually present for extractor springs.

    • In the Scotti Mod.X, like in all the weapons designed by Alfredo Scotti, the cartridge is not pulled by the extractor, but it pushes back the bolt’s head.
      The rifle infact is not “gas actuated” as normally intended, but is a “gas unlocked blowback action”. The short stroke piston has only the strenght to unlock the carrier from the bolt head, and then the head is pushed back by the residual pressure of the gas in the barrel.
      The closest “non Scotti” design is that of the Hispano Suiza HS.404 (that, according to George M. Chinn, “The Machine Gun. History, Evolution, and Development of Manual, Automatic, and Airborne Repeating Weapons”,Marc Birkigt designed after having seen the patent of the 20mm Cannone Mitragliera Scotti, that was around from 1928).
      Is worth to say that the HS.404, whose bolt had a simple straight movement, required lubed or waxed cartridges, but that’s not true for the 12.7mm and 20mm Scotti machineguns. So, in the larger calibers, the rotation of the bolt’s head was sufficient to guarantee an extraction without stressing the cartridge.
      For some reason that was not true for the Mod.X, and infact the user manual advised to moisten the cartridges, at least with the water of the canteen.

    • This is extremely interesting subject especially with historical prospective on mind and I appreciate you and others brought it up.
      Most (if not all)modern semi or fully automatic weapons do not have provision for primary extraction (with maybe of exception of M60 afaik).

      This may be due to phenomenon as described by “Dogwalker”. Yes, indeed this is most likely matter of timing between case material collapsing and residual pressure application. With today’s knowledge and predictability of material behaviour it can be well established what the size of chamber needs to be in relation to size of case; such as by commercial SAAMI standard.

      When comparing various methods of operation it seems, that the system which allows for sufficient delay has less extraction sensitivity in contrary to something like Pedersen’s retarded blowback.

      • It just occurred to me: even in given an established system it might be possible that extraction force will vary widely. I recall a study in which for example M16 had extraction force variation between zero and 160 lbs – all pretty much result of theoretical considerations.

  11. Great video, thanks.
    Have you tried to simply moisten the cartridges with water, as the user manual said it to be sufficient to guarantee the extraction?

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