I agree that you can not tell much with out that info. If I was to guess I would say they were shot into gellatin with a smokeless powder gun [there are at least 3 now] and a max load of smokeless. I say this because of the way the unbonded 250 blew, I never had one do that but I know it only takes a little more velocity than the bullet can stand,a 150 gr load of 777 might do it. Lee