One weakness of the 453 American is the single action screw. When I got mine, I noticed a tapping sound when I was handling the rifle. It was caused by the barrel contacting the forend at times because of the single screw holding things together. Before I ever fired it, I shimmed the barrel just behind the forend tip with a piece of flexible plastic.
This is clearly a defective gun. Or got a screw loose. What ever you call it, another slip past CZ ever vigilant QA dept. But it sounds very accurate, so; I would leave it be.
