Personally I've shot both the Barnes Original SSP's and the Barnes XFB. I have a TC Encore with the 18" Katahdin barrel that I use for the Iowa pistol season. It has a Harris bipod that I use and is it accurate. Obviously, I don't shoot offhand with this monster! Right now my load is 42 gr. of IMR 4198 behind the all copper XFB. I use Starline brass with Winchester WLR primers. At 100 yds off the bench I can keep all my shots inside a 3" circle pretty easily. I haven't tinkered with the orininals a lot but I am sure I will eventually because the X bullets are pretty expensive. In my opinion if you can find a good load using spitzers, you might as well use them if you're shooting a single shot. With your strong action I'm sure you could get some "fairly" flat shooting loads. Hope this helps.
Have a good one.
Trav