[rcellis]

I've accepted the idea but it come to me: why is one better ("inherrently more accurate" is the phrase I've heard) than the other?

Clint

[Jim Watson]

If the hexagonal bore were "inherently more accurate" than (conventional) rifling, then the target shooters I hang out with would use it. They don't.

The hex bore as seen in foreign firearms has advantages of long service life to ordinary accuracy standards and it is easy to make by the hammer forging system.

[Freddymac]

All else being equal, you get higher velosity with the same or lower pressure. I have read this, but have not chrono'ed any my self, so this may just be gun magizine myth. Check out the HK website, I think that they explain it.

Fred

[Steve C]

There is a velocity advantage with polygonal rifling. My compact Glock 19 will send the same ammo over the chrono at the same velocity or higher than my longer barrel full size service pistols (Berretta 92 and Browning HP).

[LexusNexus]

Polygonal rifling hugs the bullet on all sides, impacting spin to it, so it's said to generate more stability on the bullet. In terms of accuracy, I believe it's meant to say that over the long term it'll have better accuracy, ie. that bbl won't get worn down like grooves/lands would. Also polygonal bbl is more difficult to make and custom bbl makers still use the old technique, but they excel at it so the custom bbl are probably more accurate in terms of its quality. that's only for custom made barrels though. For your generic bbl, I'd say poly is better. Then again, in terms of handgun bbl length, it really won't make much of a difference.