it depends on the size, the longer the muzlebrake, the quieter the gun would be, i never tried one on a disco but i have used htem on my 1322, and my jack haley 20 cal pcp. on my 1322 when you shoot it is wuieter then openeing a can of soda, on my haley, its very backyard friendly, i find that the 6.5 inch is the best all around brake