The Unique Challenges of Self-Loading Shotgun Design

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I think a lot of people under appreciate the difficulty of making a reliable self-loading shotgun. Between the rimmed case, wadcutter-type cylindrical shape, varying shell length, and massive variations in loadings, the variability that a designer has to work around is insane…

9 Comments

  1. Just as we appreciate the genius of John Moses Browning, who was responsible for the first workable self-loading shotgun, the Browning Automatic (as it was called at FN), we should also take note of the genius of the other two men who, along with JMB, really gave us the pump-action shotgun as we know it today.

    Christopher Miner Spencer (yes, he of the Spencer repeating rifle and founding IBM) created the basic feed pattern of the tubular-magazine shotgun in 1882. The forearm-operated pump, Winchester-type lifter, and extraction system were basically his idea.

    Andrew Burgess, who designed and patented his “haveness” action operated by a sliding pistol grip a few years later, was the father of the “flap-lock-in-top-of-bolt” locking system.

    It was JMB who combined Spencer’s feed system with Burgess’ lockup, in the Winchester Model 1893, the first “modern” repeating shotgun. Then refined and strengthened it to handles smokeless-powder ammunition, resulting in the model 1897.

    (ICYDK, you can tell the two apart by looking at the top of the receiver. The ’97 has a solid-top receiver, while the earlier ’93 has a larger cutout over the ejection port. No, a ’93 should never, ever be fired with smokeless-powder ammunition.)

    As far as short-stroke gas-operated shotguns, I believe the Saiga is such a short-stroke design. But since it is after all essentially an Avtomat Kalashnikov redesigned to handle shotgun ammunition, this is hardly surprising.

    clear ether

    eon

  2. Ian forgot one.
    Due to the rapid decrease in pressure in the barrel, and so decrease in temperature, shotgun shells are ineherently dirtier than smallbore bottleneck ammo. That’s why recoil actions had remained relevant for so long in shotguns (and still are) while they had become little more than a curiosity in rifles, and that’s why gas action shotguns have complex self-cleaning pistons, often with multiple ribs, while rifles have much simpler ones.

  3. There is also another obstacle for those who attempted to make self-loading shotgun in dawn of 20th century. Namely paper-walled shotgun ammunition, which might go back due to environment considerations https://gardenandgun.com/articles/paper-shotgun-shells-ripe-revival/ Now I wonder how various self-loading shotguns.
    Also there were attempts at using different-shaped shotgun ammunition, but failed to gain traction, namely Close Assault Weapon System entrant https://guns.fandom.com/wiki/Heckler_%26_Koch_CAWS using belted design and RAS-12 https://modernfirearms.net/en/shotguns/u-s-a-shotguns/intrepid-ras-12-ar-12-eng/ using ammunition similar in shape to automatic pistol cartridge, but bigger in size.

  4. One of the most successful of the semi-auto shotguns has to be the Remington 1100. With the way the gas system is designed it runs fairly light loads up to buckshot and slugs without a hitch.

  5. [OFF-TOPIC so ignore if you wish]
    Recently I learned about new-fangled revolver design dubbed RZMK-357
    https://www.zenk.us/
    most notably it has cylinder more aft, which result in higher barrel-to-overall lengths ratio.
    It is vaunted as REVOLVER REVOLUTION, which prompts me to ask why it did appeared around 2022? Do it use some materials or solutions which were not available to manufacturers earlier? Does it outperform current designs to level that make it revolutionary?

    • That design has two problems to me.
      1) High bore axis. Revolvers in general, (apart for the Chiappa Rhino) have high bore axis, but here the distance between the barrel axis and the thumb-index web (that’s what counts for perceived recoil) is even higher.
      2) Long distance between the trigger and the sear usually means crappy trigger.

  6. “(…)varying shell length, and massive variations in loadings(…)”
    Example of recent development to counter that is R12
    https://modernfirearms.net/en/shotguns/u-s-a-shotguns/remington-r12-versamax-tactical-eng/
    where gas ports are so arranged that 12/89 will block parts of them, whilst 12/70 does not. I am wondering if placing ports so close to breech does not result in accelerated war, or in others words if expected life (number of shots) is or is not shorter than with design with ports more close to muzzle?

    • You could also try a constant-recoil system, which at least gives the bolt extra travel for stronger loads, but lengthens the receiver.

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