All it takes is an extra turn on the Lee FC die, or different primers, or hot weather, or different brass, etc. and you find yourself in the 50K psi range.
What evidence can you produce that this is so? If one uses a chronograph, and follows appropriate procedures and published load data it is unlikely to happen. With a heavier crimp, different primers, different brass or hot weather if one works up from toward the published maximum and stops if either the prescribed maximum charge or the published maximum velocity is reached it is unlikely one would even get close to 50,000 psi.
