I purchased a set of Lee RGB Full Length Sized Dies which also use a non-threated spindle and button (decapper) system. The first time I used them the decapper stayed in the case mouth. I then tightend the decapper clamp, but it still did not hold the decapper. I eventually over tightened the decapper clamp, and it stripped out the die. I sent the die back to Lee, and they replaced it, but it was a very aggrivating and time consuming experence. Good luck.