If you are just wanting to plink/target shoot, I'd go with a 148 gr wadcutter. I have had good success in my 6" Colt with 2.7 grains of titegroup and a CCI small pistol primer or 3.2 grains of Unique with the same primer. Good light load that is dead accurate out to at least 25 yards. If you want to go heavier, but not quite full magnum, any of the plated 158 grain bullets should work OK and you can still use Unique, Power Pistol or Titegroup and keep the pressures low. most of the plated bullets are limited to 1200 - 1250 fps. If you use Titegroup, just triple check your powder throws so you do not get a nasty surprise as it is a very dense powder and a little goes a long way. If you want full magnum loads, then 2400 would be my suggestion with some hard cast or jacketed bullets, but as mentioned, jacketed will get expensive in a hurry. If you are dead set on the Hornday XTP's (which are excellent), check their manuals for load data for that particular bullet. I am not at home at the moment or I would check my Hornady manual.