I assume you are talking about the so-called "full length guide rod" or FLGR, a current fad with 1911 type pistols. The original design, which went through two World Wars and a bunch of "actions" was perfectly OK, but some folks decided the springs might rub or something, and lo and behold, the FLGR came about.
IMHO, the FLGR serves only to aid in extraction. Its sole purpose is to extract money from the sucker's pocket and put it into the pocket of the seller of the FLGR.
Some, furthermore, make field stripping the pistol much more difficult and time consuming, again for no real advantage.
Worse, it was the FLGR that has given us all those firing pin block safeties. It is almost impossible to fire the original design by dropping it on the muzzle, since the barrel and slide move back and absorb a lot of the inertia. But with an FLGR installed, the slide cannot move, and the full firing pin momentum is available to impact the primer of a chambered round.
As I said, the sellers of FLGR's will now have at me, flaming me and calling me names other than
Jim