You can use a suppressor on as many hosts as you want as long as the can is rated for the particular round. Most pistol caliber suppressors will work with any pistol round smaller than the bore size, but you have to be careful with rifle suppressors because of the higher pressures. For example, most .308 suppressors will be fine with .223, but I would check with the manufacturer before shooting say, .30-378 Weatherby Mag through a suppressor rated for only .308.