Broadhead fell apart inside target - New Archery Products Killzone C.O.C. Crossbow

I was sighting in my crossbow with field tips then switched to my NAP Killzone Crossbow mechanical broadheads to see where the actual broadhead impacted the target. The tiny nut on the small pin kept coming loose. After a shot it did not matter if I pushed the arrow through the target to retrieve it or pulled it out. I basically lost the little nut on 3 broadheads. Once the nut comes all the way off, the pin can fall out and the blades fall to the ground. I called the manufacturer, New Archery Products and they were not very helpful. Customer service said that these broadheads are not designed to be shot at targets therefore they are not warrantied and they will not offer a replacement. I let the person know I was using a foam target that was intended for retractable broadheads but that did not seem to matter to him. I thought they would have been more interested in finding out why the nut was coming off the pin but that was not the case. If the nut can untwist from the pin in a target it can probably do the same thing when it hits a deer.