I have never seen one and maybe the odds would be very high. I have seen barrels that the bore was pitted and rusty from neglect and yet they shot perfect and have seen some that were new and could not hit anything with them. One thing that I can say from years of running a sporting goods store is that with mass produced products you can not be sure of what you are getting. When I was reloading I weighed each bullet and also each powder charge, Yes it was slow but I knew what I had when I finished. This subject came up because of a member having key hole problems and If I were to guess I would say the bullets are too small,don't take much to throw every thing off and could also be seating the bullet too deep
but I ame not sure that would cause the problem. Others may know for sure.
Deaconllb