There is a lot of intuitive understanding of how the gun actions work floating around that is simply wrong. And a lot of it has to do with human everyday common sense being unable to grasp a scale greater than 1 hundred. You must trust the math in order to operate in this area of gun design.

My favourite example is how many people assume that the recoil spring does anything in a blowback action aside from pushing the bolt into battery. But I made calculations for some common guns (such as AR9), and it never delivers more than 1% of the force resisting the bolt thrust when firing, and less than 0.2% for larger calibers like 10mm. The whole work of keeping the breech closed is done by the mass of the bolt. Spring does absolutely nothing!

Some of the blowback actions, such as Astra 600, have heavy recoil springs. But they only do that in order to improve the longevity of the gun.

P.S. I did not look into the numbers for the Oerlikon 20mm. I don't have the data or the time. Yes, its recoil spring is crazy strong, enough to require a pulley to charge. Even so, it may yet fall under the 1% - this is how great the bolt thrust of 20mm cartridge is.

#guns #銃