The end of the Recoil Spring Assy (RSA) for the 27 (where it comes into contact with the barrel lug) is concave in shape. That is how it is supposed to be.
The wear mark you see is most likely the metal inbedded in the frame that holds the slide lock spring in place. Yes the RSA can rub there, it's normal to my knowledge.
"As an OK State Trooper once told me, "Why shouldn't a "good" citizen be allowed to carry a gun, all the "bad" guys already do.""
Certified Glock Armorer
Last edited by Glockrunner; 10-16-2011 at 19:02..