Have a look at the back of the pellet. The good ones have a flat, very shiny indentation.
I have one tin here, which I think is from a very early production run. Some of the pellets are less than perfectly formed behind the head and have quite a rough finish to the indentation.
All the others I have, at least the tins I've opened, have been well made, although the skirt at the back is quite easily damaged.
I have been using these pellets for a while now, and I'm getting excellent results with them.
"I'm your huckleberry, that's just my game"