How tight is tight enough?

[Jeff Mayhew]

My new hammer gun was pretty tight when I received it, but after a thorough cleaning last weekend I can detect a very slight amount of play. I cut a shim of aluminum foil that is two thickness's worth (one sheet doubled over) and inserted it into the hook before closing the action. This was sufficient to bring the gun back to absolutely tight (with the forend in place).

I often hear people say that a little looseness is "nothing to worry about," but it seems to me that it transforms what should be a unified structure into a hammer and anvil that strike each other every time you fire. The effect is to compound the problem on every shot.

Any opinions on this? Thanks!