local6.com - News - New Cell Phone Guns Hard To Spot In Metal Detectors Law enforcement and authorities at government buildings are being warned to be on the lookout for guns disguised as cell phones that are difficult to spot in metal detectors... The report said the cell phone gun is a working .22 caliber pistol capable of firing off four rounds at the touch of the button. The hidden guns are made of high-grade plastic... Federal firearms agents said cell phone guns are only the latest in a long line of seemingly harmless, but lethal weapons including belt buckle guns. "There are beeper guns and there are also items known as pen guns," ATF Special Agent Joe Green said. "There are many, many disguise weapons out there..."