If the light-weight J-Mag frame wears-out at the integral cylinder-stop.....throw the frame away. If the older non J-Mag frame wears-out at the cylinder-stop....replace the lug. I suppose if you have a lifetime guarantee....don't matter unless it happens to be one of your cherished frames you'd like to keep, or don't mind the hassle of wondering what you'll get back from Smith in return. I have picked-up a J-Mag frame off the table...opened it up and had the cylinder fall off in my hand. Then...I put it back on the table and walk on.

Not pro or con one way or the other....just sayin'.