There is actually two different 209 cheddite if I remember right. One is the larger UK dimension and one the US and smaller Ok dimension. Think the big one is red primer hole and other black but cannot remember
which is which
My experience was the 1st cheddites that came to canada were the big ones and when we used them they opened the pockets in out AA hulls so you had to use just cheddite from then on
Must be 10 years ago or later the next batches started coming in were small like a winchester aa and the problem went away
I have not seen a factory challenger hull with the big primers but there could be some old ones I guess
Now we run into them big ones when we buy say 16ga hull sometimes from ballastic products or stuff like that but not anything else I have seen
Another reason I stay away from reloading Cheddite Hulls. Rare yes but is does and has happened a few times