You guys are quite entertaining. If the two barrels are one inch apart at the muzzle, they should be one inch apart to infinity with no need to worry about convergence because no one can tell the difference between a pattern that is 1/2" to the left from the left barrel and 1/2" to the right for the right barrel. Why should they converge? The shot comes straight out of the muzzle and goes straight to infinity except for the drop caused by gravity.