The above **is **the short answer. Except for very small calibers (i.e. 22s) rifle bullets are almost always designed to travel at supersonic speeds. At these high speeds anything other than a very streamlined, pointed bullet will begin to tumble thru the air *greatly *reducing its accuracy. This also accounts for the ‘crack’ sound that they make (it’s a sonic boom). Pistol ammunition is subsonic.
BTW, this is why when you see an assassin in a movie using a silencer on a high-powered rifle it’s complete bullshit.