We run Winchester Ranger 64 grain through our issue Bushy M4's, both for training and for duty.  I would highly suggest a decent 55 grain soft point from anyone other than Remington.  Highdraglowspeed is right on the mark, Black Hills is top shelf ammo.  If you contact them factory direct, they will give you special "officer pricing".  I would suggest to go with the blue box Black Hills (remanufactured).  The price is right, and the quality control easily surpasses Winchester and Remington newly manufactured ammo.