I as well have used electrical tape over the muzzle of both CF's and ML's for years. It helps prevents blockages from snow, ice, mud, etc and in the case of ML's helps to prevent moisture entering via the bore. The tape blows via the gases and is gone before the bullet reaches it. I have only ever use electrical tape due to its elastic nature. I have also used finger condoms as well.Please notethe tape is to be on the outside not inside the bore! In this video I couldn't see any tape around the bore, the slow mo replay showed something black. If that indeed was tape was it inside the bore, perhaps????