Actually, that illustration of Glock rifling is inaccurate. Rather than look like a stopsign in cross section, it has more of a smoothbore-speedbump design. My G21sf didn't lead at all, less than my Sig 220.
Now my Kahr has that stopsign shape and leads something fierce. It only gets FMJ now.
Oh and just how would someone crimp a gas check on a handgun bullet?