Gas Operation

Figure 3-31. Time-Travel and Time-Velocity Curves for Piston Before Impact With Bolt.

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Figure 3-31. Time-Travel and Time-Velocity Curves for Piston Before Impact With Bolt.

considered to be the initial compression of the spring. However, since the bolt is free of the gun, the force of the bolt spring acts rearward on the gun and must be subtracted from the barrel spring force. At the instant of impact the bolt opening is 0.0208 foot. At this deflection, the force of the driving spring is:

Subtracting this force from the correctcd initial compression of the barrel spring gives an effective initial compression of 217 pounds. The retarding effect of this force on the gun can be computed by the same methods used for developing the motion curves before piston impact. The velocity loss due to the initial compression will be:

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