I know a fella that dropped an Briley choke tube. It looked fine and fit the threads perfectly. However it was just wenough out of round that the next time he shot it the barrel bulged at the choke. He replaced the tube and shot the gun with a bulged barrel for years and years. Then one day.....
He was on a chukar hunt and he shot a double (his first). One of the birds was torn to shreds, then he noticed that his choke tube was GONE. He thinks the tube hit the bird, and I think he is right about that. (Eightbore, you know the guy)
Jeff
