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Posted: 5/10/2002 6:00:29 PM EDT
We anticipate a possible question from a reader - how far rearward should the bolt travel in a conventional auto-loading rifle and why?
According to the results of laboratory tests that were done by Prof. Alexey Konovalov of the Izhevsk Technical University, the space between the cartridge head and the bolt face (the bolt being in its rearmost position) can be as small as two millimeters. This distance is enough for the cartridge to pop up in the magazine and take the position when it can be picked up and sent to chamber. However in practice, the greater the amount of travel of the bolt group, the greater moment of inertia it generates for an ensured and a trouble-free cycle of locking the breech. Of course, inertia as a dynamic phenomenon depends on the mass of the moving part and the speed of motion. The greater the speed and the mass, the greater the inertia. As far as the mass of a moving part (bolt carrier and bolt) is concerned, it cannot be increased to infinity. A constructor always keeps an alert eye on the overall weight of the weapon ! On the other hand, a too massive mechanism may generate an undesirable bounce of the weapon and thus deteriorate its accuracy.

The weapon with buttstock folded to the right.

So the logical solution might be optimization of the mass and the increase of the speed. In a conventional scheme a longer travel of the bolt group and, hence, a greater compression and a back impulse of a return spring permit to achieve a greater acceleration of the mass during its return travel. Nikonov reduced the amount of travel. The weight of the bolt group in AN-94 is also reduced (compared to AK74). He dramatically increased the acceleration of the bolt group during its forward movement. The buffer and the shock absorber, as we have pointed it out, have a dual function:
reduction of the recoil impulse,
generation and transmission of an extra back impulse to moving mechanisms.
Again, increasing the speed and the distance, Nikonov reduces the cyclic time. The time factor becomes his greatest achievement !
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