Recoil Operation

mainly due to the retardation offered bv the barrel spring and bolt driving spring. These losses must be subtracted from the total available energy and for purposes of this analysis, it will be sufficiently accurate to assume that the losses occur at a constant rate over the interval of acceleration. That is, for the sample conditions, since there is a total loss of 50 foot pounds of kinetic energy over the interval of 0.004 second, it may be assumed that energy is lost at the constant rate of 50/.004— 12,500 foot pounds per scconcl during the acceleration process. The lowest curve in fig. 2-26 shows the result of this subtraction and gives the energy transferred to the bolt at any instant.

The values of the energy transferred to the bolt, as shown in fig. 2-26, arc used to determine the bolt velocity curve shown in fig. 2 25 as follows: The velocity of the bolt at the start of acceleration is

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