There are three excellent videos by Gregor Kamensek on YT. Two that deal specifically with the Prophet Plus in .22. A must watch for anyone considering one.
I had the pleasure of shooting with our very own Derrick Wall at an XFT in Texas early this year and watched him shoot lights out with his. So much so, Icanceled my order for a Uragan and me and my shooting buddy both bought the Prophet Plus.
We took them on our annual prairie dog hunt in June and couldn't have been happier. We were smacking dogs with confidence beyond our previous years' benchmark of 150 yards.
And know, we did NOTHING to the guns. I mean NOTHING. We didn't change hammer spring tension, reg setting; NOTHING. Zero'd the guns and went a shootin'.
As for ammo, yes we used the JSB redesigned. No, we didn't try any slugs. Just not a fan boy of slugs. Didn't need to. Bought twice the amount of ammo for the same money as slugs. Happy with the results of the redesign's. That's what RTI had the barrel made to work with. If they had wanted it to shoot slugs they would have made it a slug barrel. with the 1:32 twist, the pellet doesn't even rotate once. Only a 135 degree rotation before leaving the barrel thus reducing the roll and yaw of the pellet which greatly reduces the amount of spiral it would experience during flight with a standard LW (or other brand) barrel.