Originally Posted by Mike38
The pistol runs smoother and the slide to frame fit stays snug longer because the slide is guided straighter back and forward on the guide rod, rather than depending so much on the frame rails for guidance.
As as I understand it, the fired bullet leaves the barrel when the slide has moved a mere fraction of an inch (1/10th of an inch or so). If so, the roll a FLGR plays must have to do with consistency of lockup when the slide is returned to battery.
That said, I'm less sure than you that the guide rod plays much of a roll in guiding slide movement, because unless the guide rod itself is fitted with a bushing (like the barrel), there's generally good bit of "slop" between the slide, the recoil spring, and the guide rod. If the "guide" itself is sloppy, how can it make the slide less so?
I acknowledge that I have a lot to learn about 1911s, so I'm willing to be instructed -- but the information cited above just isn't all that clear to me.