The loss due to the effect of the spring constant as determined by the method of step 4 is, in this case, only about 0.053 foot per second. The final bolt motion curves shown in fig. 2-24 are the result of performing steps 2 and 3. Since the velocity loss due to the effect of the spring constant is so small, it is not necessary to perform step 5. Note that the displacement between the barrel at bolt at 0.005 second (as indicated by the travel curves) is 0.0208 foot or 0.250 inch as required. The retarded velocity curves for the bolt and barrel show

that at the instant acceleration starts, the velocity of the bolt is 36.7 feet per second and the velocity of the barrel is 18.5 feet per second.

5. Motions during period of bolt acceleration

When the cycle of operation has progressed for 0.005 second as described up to this point, the residual pressure has decreased to the assumed safe operating limit of 750 pounds per square inch and it is now possible to increase the velocity of the bolt without danger of rupture of the cartridge case. It should be noted that at 0.005 second, the residual powder gas pressure has not yet reached zero and

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