Interesting terminology you use. I have my Dad's "Sporterized" 303 in the safe. I have no issues with running surplus ammo thru it. And to those who have not fired one of these things, after you do, you have a whole new respect for those guys who had to fire one ALL DAY LONG.BTW-do ya know what happens to a duck when it is hit squarely with a .303 round?:0