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Figure 2-36. Barrel and Bolt Motion Versus Time

During Action of Accelerator During Counter-

Recoil.

plot curvcs showing the variation of the velocity and travel with respect to time. These curves are shown in fig. 2 36. The data from these curves can now he used to extend the time-travel and timc-vcloc-ity curves of fig. 2-30. Note that the action of the accelerating lever increases the barrel velocity from 4.8 feet per second to 15.0 feet per second and decreases the bolt velocity from 48 feet per second to 30 feet per second and that this result is accomplished in 0.0045 second. The total time from the beginning of the cycle up to this point is 0.0441 second.

12. Barrel and bolt motion after 0.0441 second

At the point rcachcd in the prcccding analysis, the relative displacement between the barrel and bolt is equal to 0.0208 foot (0.250 inch) and the parts arc located at the same position in which the acceleration action began during recoil. However, the action of the accelerator docs not stop at this point during counter-recoil because the level is still between the barrel and bolt and will continue to act until the bolt reaches the barrel and locks in place. The remaining movement is so small that it will be accomplished in a very short, time (approximately 0.0015 second) and therefore the shape of the small portion of the lever which acts during this interval is not critical. On this basis, it is assumed that after 0.0441 second the barrel and bolt velocity curves will follow the same trends as before this time. For the subsequent interval of approximately 0.0015 second, the average bolt velocity as shown in fig. 2-30 will be about 16 feet per second and the average bolt velocity will be about 30 feet per second. This means that the average relative velocity between these parts will be approximately 14 feet per second and the time required for the barrel to strike the bolt will be: