Several years ago (15-16) there was a discussion on a forum about using a shell standard holder in a impact bullet pulling tool. The thread stated out with a question "I heard... using a shell holder was dangerous and a round will go off". Several pages and maybe 40 posts later, no on had experienced around discharge in in an impact puller using a shell holder, or anything else for that matter, nor could anyone confirm the possibility. Yep "Internet wisdom". I think I used the aluminum collet once or twice then put it in a drawer, somewhere...