I’m not super familiar with firearms and usually only see them in video games. I notice that pistols and sub machine guns use something called blowback to load the next round from the magazine. My understanding is that the recoil of the round pushes the bolt back and ejects the bullet. This works for pistols and submachine guns like a Glock or MP40.
For rifles though, they have to be gas operated or put in a separate tube so that the gas can go backwards to push the bolt back. Why is this the case? Why can’t rifles like the M16 or AK47 simply use blowback and let the recoil of the gun push the bolt back and load the new round?
In: 26
You do have blowback rifles.
In all firearms, the action needs to keep the chamber shut until the pressure inside is low enough to safely cycle the action.
The pressure generated by a pistol cartridge is low enough that a heavy bolt with a spring can keep the chamber sealed for long enough.
Rifle cartridges have much more energy and generate much higher pressures for much longer. It is not practical to rely only the mass of a bolt as it would need to be very heavy to keep the chamber sealed for long enough.
Instead, the bolt is mechanically delayed through various means. This is also the case on some pistol calibre firearms such as the MP5. It is roller delayed, so the bolt and therefore the weapon, is much lighter than with a simpler bolt.
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