It is my understanding that some (many?) semi-auto pistols are not 100% reliable with pre-fragmented ammo. I know some people hand-cycle their pre-fragmented ammo to check its feed reliability and/or only carry the pre-frag as the chambered round, but that doesn't address the problem. It's not a matter of the bullet nose profile causing failure to feed problems, it's that the slide may not cycle just right and fails to pick up the next round from the magazine due to the different recoil impulse generated by the extremely light weight projectiles of pre-frag ammo as compared to standard weight stuff. For example, I believe the FBI HRT, when they were using Glasers in Hi-Powers, had special springs for the gun to ensure reliability with that load. Since it's advisable to run 100-200 rounds of *any* self-defense load being used as carry ammo, do you have the $$ to do it with Glasers, et al.?! I know I don't! I generally recommend pre-frag ammo for revolvers only... "but that's just my opinion and I could be wrong."
Steve