Interesting, I have a STI Targetmaster with 6" bbl. They are 1:16 and when I first got it couldn't get it to shoot better than 6"-7" at the 50 out of a Ransom. Sent it back to STI twice and they replaced slide, then finally bbl and I am getting 2"-3" at 50 now with 115 grain JHP Wincheser boolits. They wont tell me what bbl they are putting in them, but whatever it is quality something to be desired(at least one I got)Now I know why the person I bought it from sold it. Shame, it is a solid well built pistol, but lacks ability in what it is supposed to do. Must say their customer service was top notch. Everyone I have since talked to that had one has changed the bbls in them. Several said the lower end Trojan shot better than the Targetmaster.
As heavy as the slide is have to load them up around the 1200fps to get the thing to function, but recoil still mild with all the weight. If I keep it, might have to invest in another bbl, but hate doing this to a gun that is supposed to have performed good to begin with. I know my shooting prowess has depreciated, but out of a machine rest, as someone stated previously, takes the stoopid factor out of the equation,it should perform.
In the past we have tried some 90 XTP's grain JHP boolits out of the PPC9 and Targetmaster and they were all over the place.Maybe need to try some of the 100 grain lead SWC in the Targetmaster.