Hmm, I'm not an expert on the provisions of airguns, but I do know that those baffles WILL reduce a db or more when and if the BATF would test that "muzzle break".there are provisions in place for using the device on an air rifle or 1/2 the people on air rifle forums would be in jail.
So without it registered and $200 tax stamp you would be in some hot water.
Like this guy.