I have seen a youtube video of a .22 fac FX air rifle with the smooth twist barrel that made it look quite impressive. Never heard of a .177 that was any good though. The theory of a smoother projectile having less drag therefore maintaining not only velocity but also more rotational rpm's is sound though. The smooth bore also seals better reducing air leaking past in the rifling grooves reducing air consumption which should also tighten the velocity spread.
I am making my own interpretation of an alternative barrel at the moment, in .22, If successful I will have a go at a .177 too.
HFT, for people with only 2 buttucks!
VooDoo TwoTwo The next chapter.