There is a fair amount of variety in M33 projo's.... all similar, all a little different. Profile a little different, weights between 647 and 690 grains....
I generally use .64 or .65. You mileage may vary....
I have found the AP that run 690 to work great out of my Windrunner. Very consistent and very accurate to the point that it is close to Amax. It isn't but it gets pretty close. They are pretty cheap also from HiTech and are already run through a sizing die.