Which one has fastest cyclic rate? -

Assuming all use same caliber are open bolt and all other variables are the same between them.

bonus question: How do you calculate the bolt recoil/throw distance if you know the spring strength, bolt weight, bullet weight and muzzle velocity.

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  1. 1 year ago
    Anonymous

    D

  2. 1 year ago
    Anonymous

    D
    eez nuts

    • 1 year ago
      Anonymous

      D

      its A....I promise

  3. 1 year ago
    Anonymous

    Is this a blowback system or gas operated? With blowback you need the bolt to be heavy enough to keep closed until the bullet leaves the barrel. A light bolt on a blowback gun can result in the brass case bursting since it is pulled back out of the chamber while the pressure is still high.

    • 1 year ago
      Anonymous

      >asks a question
      >gets an unrelated response

      oh good I am on PrepHole

      • 1 year ago
        Anonymous

        It is related. You can't just change the bolt mass at will in a blowback system. You are literally required to keep the bolt heavy. The bolt on my 9mm CZ Scorpion is quite heavy. Meanwhile I have a light titanium BCG in one of my ARs that weighs like 1/4 as much as the scorpion bolt.

      • 1 year ago
        Anonymous

        Here to save the day:
        In a blowback system with a barrel longer than say 8-10" the spring contributes a negligible force... The bolt weight dictates the speed of the recoil stroke, the spring only affects the forward bolt speed...theres a speed limit however
        >spoiler its 10m/s
        go faster and the feeding and ejection cycle start to overlap (this is why ultra fast reciprocating guns like the calico and am180 have top down, straight line cartridge flow.....

        all the info you want is in books,

        >These Books
        "The Machinegun" By: George Chinn
        >google it they're free online

        thank me later

        • 1 year ago
          Anonymous

          now answer the bonus question, nerd

        • 1 year ago
          Anonymous

          how do handguns get away with such little recoil space for slide/bolt? some have pretty long barrels

          • 1 year ago
            Anonymous
            • 1 year ago
              Anonymous

              how do you explain blowback pistols like makarov?

              • 1 year ago
                Anonymous

                also hipoint

              • 1 year ago
                Anonymous

                also hipoint

                Hipoints just have heavy as frick slides. Look at them. They are thicc compared to normal handguns. I have never looked into how a Makarov works so I can't speak on it.

              • 1 year ago
                Anonymous

                [...]
                Hipoints just have heavy as frick slides. Look at them. They are thicc compared to normal handguns. I have never looked into how a Makarov works so I can't speak on it.

                makarov is in 9x18mm. it's not full power cartridge. hipoint is thicc

  4. 1 year ago
    Anonymous

    Step 1: Conservation of momentum (equate projectile/gas momentum to bolt momentum; solve for bolt velocity)
    Step 2: Conservation of energy (equate kinetic energy of bolt to potential energy in spring)
    Step 3: Use spring formulae to calculate bolt travel and spring force at max travel

  5. 1 year ago
    Anonymous

    A is the fastest cyclic rate.

  6. 1 year ago
    Anonymous

    There are also things to consider such as bolt bounce. A light bolt slamming shut at high speed can literally bounce back and re-open the bolt. This can either cause a case failure since the gun fires with a partially open bolt or cause malfunctions.
    You can also outrun the magazine and the bolt can start coming forward faster than the magazine can push a bullet up so it gets picked up by the bolt.

  7. 1 year ago
    Anonymous

    Likely A.
    You can somewhat understand it better by understanding simple harmonic motion.

    natural frequency [cycles/second] = sqrt( k / m )

    k = spring rate/restoration force
    m = mass

    So, the higher (heavier) the spring rate and lower the mass, the quicker it will cycle all else being equal, and assuming things like free recoil.

    Bonus question is a bit more complicated, and someone smarter that actually knows what they're talking about can probably answer it much better or know a better way. But you can probably take the differential equation for spring-mass-damper systems and the dirac delta function for impulse step response, m x'' + c x' + k x = u(t), plugging in the values, taking the Laplace transform, blah, blah, blah

    It's easier if you just google videos on impulse response for second-order systems.

    • 1 year ago
      Anonymous

      https://i.imgur.com/Nem0mfY.jpg

      first order mass spring equation.
      >spring is on top so make K bigger to make it go faster
      >mass is on the bottom so make M smaller to make it go faster

      There's really not much else to it than this, (A) a stiff spring and light bolt is the answer. You learn this in any undergrad mechanical vibrations or controls course. The transient response of a second order system (e.g. spring mass damper) is characterized by the natural frequency and the damping ratio (actual damping divided by critical damping). The settling time is inversely proportional to the product of the damping ratio and the undamped natural frequency of the system. You select damping ratio based on the maximum overshoot, so for a breech that means no maximum overshoot or in other words critically damped, so damping ratio is practically one. Answer: maximize sqrt(k/m)

  8. 1 year ago
    Anonymous

    first order mass spring equation.
    >spring is on top so make K bigger to make it go faster
    >mass is on the bottom so make M smaller to make it go faster

    • 1 year ago
      Anonymous

      Stupid question from a stupid anon. Going to show how much I don't know I don't know here: let's say anon is loadong .356tsw and firing from a g17. How does anonsmoothbrain calculate how much extra spring force is needed to prevent case blowouts, by slowing the unlocking of the breach, without being so much that the slide is incapable of completing it's rearward travel? Where can anonsmoothbrain find information on how chamber pressure spikes and drops with microseconds of time, and then the browning action begins to unlock, so that anon can try to understand the timing needed to replicate similar levels of chamber pressure with significantly higher pressure loads?
      -t.college dropout

  9. 1 year ago
    Anonymous

    Obviously a.
    But too heavy spring may mean bolt doesn't clear round in the magazine. Also too light bolt may mean case moves out of chamber to much before pressure fall and case would rupture.

    • 1 year ago
      Anonymous

      It is related. You can't just change the bolt mass at will in a blowback system. You are literally required to keep the bolt heavy. The bolt on my 9mm CZ Scorpion is quite heavy. Meanwhile I have a light titanium BCG in one of my ARs that weighs like 1/4 as much as the scorpion bolt.

      Is this a blowback system or gas operated? With blowback you need the bolt to be heavy enough to keep closed until the bullet leaves the barrel. A light bolt on a blowback gun can result in the brass case bursting since it is pulled back out of the chamber while the pressure is still high.

      couldn't you just use a lighter bullet/less powder charge as well?

  10. 1 year ago
    Anonymous

    I dun get it how come putting a stronger spring in a ar can counteract being overgassed if the spring only affects return speed?

  11. 1 year ago
    Anonymous

    >create pictures to illustrate question
    >make all the pictures the same
    Are you mentally deficient? Serious question.

    • 1 year ago
      Anonymous

      accounting for lowest common denominator, anons need visual stimuli.

  12. 1 year ago
    Anonymous

    >How do you calculate the bolt recoil/throw distance if you know the spring strength, bolt weight, bullet weight and muzzle velocity.

    We'll ignore all other forces acting on the bolt, and pretend the recoil spring exerts a constant force, rather than increasing as the spring compresses. If you know the force in battery and in full recoil, take the average of the two.

    initial bolt velocity = muzzle velocity * bullet mass / bolt mass

    initial bolt energy = bolt mass * (initial bolt velocity)^2 / 2

    bolt travel = initial bolt energy / spring force

    So taking typical figures for a 9mm SMG:
    >bullet = 124 grains = 0.018 pounds
    >m.v. = 1200 fps
    >bolt = 1.5 pounds
    >spring = 10 pounds
    initial bolt velocity = 1200 fps * 0.018 pounds / 1.5 pounds = 14.4 fps
    initial bolt energy = 1.5 pounds * (14.4 fps)^2 / 2 = 4.8 foot pounds
    (if the numbers don't look right, remember there's a factor of 32.2 (g) in there, because we're going back and forth between pounds mass and pounds force)
    bolt travel = 4.8 foot pounds / 10 pounds = 0.48 feet = 5.8 inches

    And since typical SMGs don't actually have 6" of bolt travel, this immediately highlights the reality -- typical SMGs (along with most self-loading firearms, of whatever sort) are designed so that the bolt slams into the receiver with some significant fraction of its velocity remaining, so this sort of analysis is not terribly helpful. The bolt travel is usually dictated by the minimum mechanically acceptable travel (i.e enough to clear the magazine) plus some reasonable margin, and the recoil spring by the work it needs to do during counter-recoil (stripping and chambering a cartridge), with little direct relationship between the two.

    • 1 year ago
      Anonymous

      6inches isn't that big(don't kid yourself dude), how is there not a single smg with 6 inches of space for a bolt to naturally return to home, wouldn't it be super easy to control?

  13. 1 year ago
    Anonymous

    A runs fastest, assuming it runs at all.
    A third factor, a huge one, is excess bolt travel distance. Going half as far is kinda like going twice as fast. Look up the macjack buffer for example.

    Here's some interesting blowback bolt weight info:
    https://web.archive.org/web/20190314104641/http://www.orions-hammer.com/blowback/

  14. 1 year ago
    Anonymous

    The fastest firearm (with a single barrel) was the VP70M with 2200 RPM.

    Rise is caused by two primary factors
    1. The force of the action, aka the mass and deceleration of all moving parts during rearward travel, for instance on a pistol slide you would use the unlocking pressure minus the inertial drag of the barrel and slide minus the spring.
    2. The moment arm of the forces acting on the stabilizer. Could be bore axis, or stock height depending.

    Its a lot of work and not a one size fits all equation but if you read up on it it's possible to find what you're looking for.

  15. 1 year ago
    Anonymous

    A

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