Quote from mig1nc:
"Without the plate on your P-01, would that Vortex sit low enough to cowitness stock sights?"
The answer I believe is NO. But you could confirm what currently available optics might from the knowledgeable shops that mill like Primary Machine, CGW, CZC, etc.
My other P-01 was milled by Primary two years ago to fit a Shield RMS. Small enough to fit between the stock sights for co-witness, but IMHO it's a cheaply made and expensive optic and I wouldn't recommend it. There are a number of new micro optics coming out and I'm especially hopeful that the Holosun 407K/507K will be small enough to fit between the stock sights and lower 1/3 co-witness like this:
