Hello. Enjoy your new HP; they are grand...at least to me.
Not knowing if you have an older or newer HP, I recommend the following:
Shoot some standard velocity ball to check function and get used to the gun. (I like PMP as it groups out of HPs and clocks only 1120 ft/sec with its 115 gr bullet. It's cheap and the cases reload OK.)
If it works fine with ball and you want something with a bit more horsepower for defense or for popping small game, the
standard velocity 115 gr Federal JHP (9BP) has a roundnose ogive. It gets a bit over 1100 ft/sec, has a good "street reputation" and generally groups well. I'm partial to the same company's 124 gr Nyclad HP, which gets about 1100 ft/sec with this nylon coated hollowpoint. In most of my HPs, this load groups very well. Neither will abuse your pistol. The fastest standard pressure load I'm aware of is the Winchester 115 gr Silvertip @ approx. 1200 ft/sec.
If your HP is a newer MkIII, I'd sure consider +P for the times I wanted to send the best! I routinely replace the factory recoil spring with a Wolff conventional 18.5lb recoil spring and use shokbuffs from Buffer Technology. These, in my view, limit or prevent long-term excessive wear. Loads I use in these guns include CorBon's 115 gr +P JHP at about 1380 ft/sec or Triton's 125 gr +P JHP @ about 1245 ft/sec. My guns really group with this latter load.
Best.
