Stan - no offense taken.

On a side-by the mirage is most intense right over the juncture of the barrels, i.e. the ribs. As nasty as mirage can be, it dissipates pretty rapidly with distance, so that little quarter inch ends up being a big deal. Not perfect, mind you, but it goes a long way. Hell, even when I shoot trap doubles with my O/U I will finish the round with mirage.

In the case of trap doubles you're lighting off both barrels about once every 30 seconds. They get hot, Damn hot. My casual observation is that that shotgun barrels, thin as they are, tend to cool very quickly, so that if your rate of fire slows down a bit, say two shots every 60-90 seconds, mirage is a much smaller problem.

Cheers