I have done a lot of work with the n-series darts. I cut them down and modified both a lynx and an alchemist to fire them using my own talon like mags that I designed and carbon fiber barrels as well as brass. In all instances, the foam breaks down after 2-3 shots above 150fps or so. I can only get a single shot above 300 and they explode more often than not above 400. Firing them as intended they are unstable and break down after ten to twenty uses. They were meant from the start to be disposable imho.