Be careful of polygon barrels, I am told they can be very pellet fussy. Worth a try though, just to see.
If you like to mess with stuff, but still have a rifle useful for ft and hft, I'd be looking for an Air Arms Pro Target. I have five or six different barrels, including a Career barrel, which has teeth not lands to spin the pellet, that will fit straight into a Pro-T. You can also experiment with regulator pressure and volumes pretty easily.
Whatever you choose, have fun, it's a fascinating side to shooting.
"I'm your huckleberry, that's just my game"