Well, sorta. I parked a 1911 slide using standard manganese phosphate parkerizing solution and got the standard dark grey.
The I mixed up a homemade blueing solution by modifying the ammonium nitrate-lye formula to use potassium nitrate instead of ammonium nitrate. I brought it up to about 290 F and cooked it for 1/2 hour. That did the trick... it gave the deep black I have been after for a 80% 1911 build with a parkerized finish.