Aguilla ammunition makes a .22 RF round with a 60 gr lead bullet. Looks like a 22 short case with a full llength 223 (rn) bullet. Goes somewhat subsonic, and for accuracy needs a 1 in 9 twist barrel (available for the 10/22 but it takes a bit of looking). Really accurate with the right barrel, extreme penetration (shoots right throgh a redwood or cedar 4x4) and no supressor needed. they work semi auto actions as well.
Which brand is that? I know the neighbors would like something a lot quieter than stingers.