Marlin, fwiw, in the past I loaded .357 cases with 10.5 grains of Blue Dot w/ 158 gr. bulk Win. jhp's and mag primers and it seemed pretty " peppy " in both recoil and blast from a Ruger GP100. ( And I'm not a recoil sensative guy ) . Alliant claimed this was a max load at the time. Lately, I have been loading a 158 gr. plated fmj flat point with 9.4 grs. of Blue Dot & mag primer in .357 mag cases and it is an accurrate and pleasant shooting load that still let's you know you aren't shooting a .38 spl. I have no reason to think that it won't work just as nicely with those bulk 158 gr. Jhp's, or possibly your XTP. This latter load is certainly not a full house load, so if that is what you seek, you'll be dissapointed . Best of luck and happy shooting.