I think the self pruning system rarely works, because there is some kind of correlation between being nuts, and being lucky. I had a friend that called me one day, and asked how he could stop his Ruger old army from self cocking. I went over and examine the gun. He was shooting bulls eye in it. He bought a Shiloh Sharps "old reliable" in 45-120 and complained about how much it kicked. I checked his loads and found he was shooting a hundred grains of 3f, and 8grains of red dot. He finally did blow up a gun. It was a cheap single shot box lock pistol kit gun. He put smokeless in it and when he saw me run like my hair was on fire, decide that he would be safe and stand on the side of his work shop, and reach around the corner to shoot the pipe bomb. It blew up leaving him holding the wooden grip. He didn't get a scratch, but moved the doorway to hide the gaping hole in the siding. His kidneys fail from over indulgents, and he got moved to the top of the transplant list, because they found a 100% match. He lived another ten years, and died from a heart attack, in his Lazyboy.
Hungry Horse