Just forwarding the info:
Exactly what is the difference between the Crosman Premiers in the card board box and the Ultra Magnums in tins both in 14.3g?
The answer was the age of the die pressing them.
The chemistry is the same, the process is the same.
Premiers in cardboard boxes come from the tightest tolerance and newest die for that pellet weight.
Once QC determines that the +/- tolerance is beyond their threshold of acceptance the die is retired from making Premiers for the cardboard boxes, and they package the next run of pellets for the 500 tins called Ultra Magnums.
The pressing process eventually wears out die completely and it is retired from any use.
DIE A,B,C etc make Cardboard boxed Premiers until out of spec, then they shift to tins.
Die D,E,F are then used to make Premiers in cardboard boxes, and the process starts over again.