with brand new mag you can get away with PC, but old mag (because the corrorsion is already deep)you take a chance of them gassing off and bubbling the clear at 325* temp. I think Gibbs brand would be a better choice then WD40 on the Dow7. I don't like Gibbs on polished mag as it dulls the shine that makes the mag look so good, at that point it looks like polished aluminum