Almost all common rifle cartridges fire seriously supersonic bullets even ~OUTT at 800 meters. Mach at sea level on a STD day is, IIRC, around 760 mph or around 1100 fps.
5.56x45 with a standard 55 gr bullet leaves a 20" bbl at over 3000 fps. The bullet breaks the sound barrier all along its flight path for at LEAST 800 meters, and that is the source of the loudest (and promptest) sound to anyone along the line of flight more than mebbe 10 feet from the muzzle.
There is no silencing a supersonic rifle round. One might reduce the muzzle report some decibels, butt the moment the bullet leaves the muzzle it's leaving a sonic boom wake and it sounds like a 'crack' and cannot be suppressed in any way (as long as it is supersonic).
Truly silenced firearms are typically large caliber SUB-sonic rounds like a .45ACP, special low-velocity 147gr 9mm rounds made for use in silenced firearms, or seriously underpowered (typically handloaded) rifle caliber rounds and for the .22LR fans, Remington sells a special subsonic .22LR so sonic booms don't bother your neighbors when you're shooting a RAT in yer backyard.
And subsonic cartridges have very short range and are useful only in short range use and generally nott as sniper weapons for distances over 50-100 meters. Plus the wounding effect is generally less than the full-powered equivalent round.
So 'silencers' for rifles is really a non-issue in the real world. As was pointed ~OUTT by another poster, they are principally flash suppressors and provide some decibel reduction in indoor shooting ranges.
AI
