I use the NAP Spitfire 100gr mechanicals. So far so good. No failures or premature opening so far. The blades do however loosen up after about the 5th shot or so. I would use a brand new one from the pack for hunting. I would do that with any BH's. Just my opinion though. Took a big doe a few weeks ago using them. Complete pass through and demolished both lungs. It put about a 3/4" diameter hole through both sides. Couldn't find the bolt. I was quite impressed with the wound channel it left. She didn't know what hit her. She dropped, got up and ranalittle waysinto a corn field. I was surprised she evenwent that far after falling over once,then getting back up. WHAAAAAMMMM!

chris