A friend of mine bought the Hatsun Bullboss 25 cal about 2 month ago from Amazon. He has not shot all of the pellets from a single tin of JSB MK2. The gun failed and would not cock. I remove the assembly from the stock and found this broken metal tab in side the receive where the hammer and spring are located. The gun cocks and fire now. But what is this component ? I looked over the parts diagram and I do not see anything there that looks like this part. Hatsun is Impossible to contact by phone. Any help would be appreciated.