Open the breech by hand and examine the motion to see that it's regular, particularly the firing pin retraction. Depress the foot-firing pedal to launch the firing pin, and repeat above measurement. https://xn--l3ca4b8epb5b.com/category/%E0%B8%84%E0%B8%A5%E0%B8%B4%E0%B8%9B%E0%B8%AB%E0%B8%A5%E0%B8%B8%E0%B8%94%E0%B8%A1%E0%B8%B2%E0%B9%83%E0%B8%AB%E0%B8%A1%E0%B9%88/