I think it happens in my Super DISC because the tolerance is not as tight as my other Knights. Ive shot some beefy loads in my 54-120 and no primer has ever stuck in it. Im talking 120gr of BH209 and a 385gr Rem CLHP in a tight 54x50 sabot.

My Super DISC will stick with a Fed209A with almost any load. The anvil backs out of the primer cup. A quick re-firing the spent primer allows it to fall out like normal. On the same range session, same load and next shot i can use a Win209. It will fall right out of the adapter.