First make sure they are legal to hunt with in your area!! Second...they act as a muzzle brake and reduce recoil along with the blast from the gun...hunting with most subsonic suck due to low velocity (under 1100 fps depending on conditions), but yes very quite..with normal loads u can still shoot most normal calibers without hearing protection because it removes the gun blast but not the super sonic crack,,, which occurs down range away from you... and in most cases, suppressors will increase velocity....last if u buy a name brand suppressor u wont b disappointed...most all have figured out how to make them quite, now trying to make it small and light...smaller and lighter cost more......oh as far as making one,,I think u need a manufacturing license?