buzz, looking through Lippard's book I find only a couple of clues to your question. On p.22 he writes:
"The MX12 is a refinement of the MT6. It has a single trigger with a fixed coil spring mechanism. Coil springs for low maintenance. Primarily a hunting model, it was offered in a Sporting Clay weight (7 lbs. 12 oz.) configuration in 1991 to present. Sea shell sculpted frame with engraving makes for a beautiful gun. No side ribs offered until late 1992. "C" denoted choke tubes. Flat rib."
Then on p.71 this:
"If you look at a MX12, MX5, and other coil spring models, you will find that the hammers are not rebounding. The firing pins therefore are not rebounding either. They protrude out of the breech face. But, there is an ingenious thing that happens in one of these model Perazzi. Move the top lever, and the bottom hammer is withdrawn. The firing pin, under spring tension, therefore is withdrawn too."
Nothing definitive on action type, but maybe it will help you connect the dots and get an answer. I dunno.
Best, SRH
