If you mean "Parkerizing" the answer is no; but, if you mean "Phosphateizing," as done by gun finishers, the answer is that it is every bit as good.
"Parkerizing" is a registered trade mark of the Parker Chemical Co. and their product has not been used to finish firearms since the Great War. It was extremely durable and extremely ugly, being a kind of sickly green.
Note that the Brownell catalog has "Parkerizing" in quotes. It is a violation of trademark and copyright laws for a metal finisher to advertise that he uses a propriatary process when he, in fact, uses comething else. It would also leave somebody open for a lawsuit claiming degradation of product identification. Parkerizing is used extensively in industry to put a durable finish of machinery and certain vehicle parts
but the chemicals are costly and even the arsenals used a different process eventually.
Or, so my reference material states.