I was going to use the 92L0 that I had access to, but the owner has used a B-Square (non-gunsmithing) mount which has worn/thinned some blueing away around the ejector screw.
I'm told by those with a lot of finishing experience (and experimentation) that the "greenish" tint to the parkerizing is a product of a "chromic acid" bath upon removal from the park tanks.
I believe this was done to stabilize the reaction before/instead of using water.