User blog comment:Dr. Feelgood/Suppressors and bullet dynamics/@comment-1260687-20100310014109

Sorry, Blinzy, you're wrong as well. Cooler gas escapes with less velocity, reducing muzzle velocity. For rifles, subsonic ammunition is also (typically) used when employing a suppressor. The number "15" you're thinking of is a rough average of the percentage of impulse reduction experienced when a suppressor is used.