They way your describing the retention of the Ball is called Staking. It's commonly used in the Automotive Industry to retain the cups for the needle bearlings on UJ's on propshafts. I have never heard of the UJ's flying apart nor the spring powered ball on an Air gun latch coming out. and that design has been used for many ................ many years indeed on many diffeent makes.
Oh I once had someone tell me that the Feinwerbau Sport models 124 & 127 were poorly made as the barrels wore loose. Turns out this "Person" thought himself a Gunsmith and had got hold of another barrel and fited it to make it a switch barrel. It was his workmanship which was at fault not the makers
If a ball came losse I would suspect that soem Home Gunsmith and I use the term loosely
had been fiddling with it.