I just purchased new plugs for my 502 and the spec is .045. The plugs come gaped around .03. When I enlarge the gap by bending the rear of the ground, the surfaces are no longer parallel. Is there a way to properly gap these? Take a look at the pictures below. I'm just using a standard flat feeler gauge but the gap on the outside obviously larger than the inside. I was thinking about tapping it flat while the gapper is still in it to hold the gap. The plug on the left is original and on the right was my attempt to gap. The plugs are ngk br6fs.