I assume the groove in the muzzle end of the barrel is designed to help locate the barrel in the slide properly. Seems to me the thickness of the barrel at the narrow portion of the groove would be VERY thin. Have there been any reports of kablooey's with the Ruger autos that have the grooved barrels? I note that the Security 9 manual has an admonishment to avoid +p+ and the American does not have this verbage.