Breech Housing

LATCH RELEASED' Figure 2-18. Action of a Catapult Spring Accelerating Device.

alone and this by itself reduces to a considerable extent the amount of energy transferred. Furthermore, there will be friction and impact losses and other inefficiencies in the mechanism which also will reduce the velocity gain factor. All things considered, the velocity gain in any practical, well designed mechanism will probably be such that the bolt velocity after acceleration will be approximately 1.5 times its velocity at the start of acceleration.

It is well to mention here that the same general conclusions apply to accelerators of the lever or cam type. Merely increasing the lever ratio in a lever-

type accelerator will not result in a higher velocity gain. In the final analysis, there is only a certain amount of energy available in the recoiling barrel and no matter how efficiently this energy is transferred, the change it can produce in the velocity of the bolt is definitely limited. A lever ratio which is too high will result, not in a greatly increased bolt velocity, but in excessive strain and shock on the mechanism.

The preceding analysis has been concerned with the three basic factors which determine the bolt velocity in a short recoil gun. These factors are:

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