I havent shot them yet but played around to see how well the blades deployed. Just for a generic test media I used some fairly thin paper. Pushing the head through the blades did not deploy, but the paper was pretty thin and flimsy. I folded it in half so it was doubled up and the blades deployed everytime. I liked the fact that the blades were held in place well, because I have heard of some people havingdifficulty keeping the blades inwith differant brands of mechanicals. Almost like they deploy to easialy. With the tekans that isnt the case, but the deploy easy enough to were I would be confident they would open on anything you can shoot. Time will tell but I plan on using them this year. I really like the fact that they stepped up to an inch and a half cutting diameter.