USE OF THE REGULATOR.
In order that the working of the gun may be regular, sufficient power must be available to ensure complete recoil of the piston. The amount of power necessary must vary because of insufficient oiling, dust, or fouling in the mechanism, &c. Then, again, pressure of the powder gases may vary because of temperature, deteriorated powder, or badly worn rifling.
The regulator affords means of varying the power which works the gun. Under normal conditions it should be set at 25.
To test the automatic action, fire several shots with regulator set at 25 and cocking handle at “R,” and observe:—
(a) One shot should be fired at each pull of trigger. If more than one shot is fired at a time, it shows that piston does not recoil sufficiently after each shot to catch on sear. (b) Claw of pawl should catch in the opening in strip at each shot. If pawl rides on top of strip instead of catching, it shows that piston does not recoil sufficiently to throw feed lever through a complete stroke. (c) The ejection should be regular and energetic.
If these three points are not satisfactory it may be concluded that there is a lack of power, and regulator should be screwed up from 5 to 10 divisions.
On the other hand, too much power is not desirable, as the vibration due to the violent action of the mechanism necessarily affects accuracy.