MechanismsBlowbackIn "blowback" operation, the bolt is not actually locked at the moment of firing. To prevent violent recoil, in most firearms using this mechanism the opening of the bolt is delayed in some way. In many small arms, the round is fired while the bolt is still travelling forward, and the bolt does not open until this forward momentum is overcome. Other methods involve delaying the opening until two rollers have been forced back into recesses in the receiver in which the bolt is carried. Gas operatedIn a gas-operated mechanism, a portion of the gases propelling the bullet from the barrel are extracted and used to operate a piston. The motion of this piston in turn unlocks and operates the bolt, which performs extraction of the spent cartridge and via spring action readies the next round. Almost all modern military rifles use mechanisms of this type. Recoil operatedIn some small caliber weapons, the bolt is not restrained but is relatively heavy and held against the breech by a spring. The gas pressure in the cartridge and the weapon recoil acts to push the bolt back, but owing to inertia this action does not significantly cause loss of gas pressure until after the bullet has left the barrel. Subsequent action is similar to that of the gas operated mechanism. This type of action is simple and inexpensive to manufacture, but is limited in the power it can handle, so it is seen on small caliber weapons such as machine pistols and submachine guns. See alsoI believe the M16 is gas operated, and as a former drill sargent I have done much study on this weapon durring small arms training. You even say so yourself. http://en.wikipedia.org/wiki/M16_rifle Please delete this entry by Miss Information. Thank you. Wick is a tool. References
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