This is like the gentleman I came across at the range one time. He had just purchased a used TC Contender and asked me why the holes in the target were ragged stars. After examining the pistol, I found that he had the ribbed barrel that fires 357 Magnum and 410 shotshells (when you install the
star-shaped choke in the muzzle).
I asked him if he had received an odd-looking turnkey with the gun. After he replied to the affirmative, I informed him that in order to fire 357 rounds from this barrel,, he needs to remove the choke from the muzzle.
Actually, I was surprised that no damage was done to the pistol or him.