Please excuse my ignorance....what is the significance of this? Was there a recall or something? I don't really understand your post.Make sure you check the serial number against the "upgrade" list through Glock. It would be a shame for you to buy a wonderful 357Sig just to have to send it to GA for a month to get a new frame. If it's an E series thats had the "upgrade" it will have a 1 at the beginning of the serial number on the frame that's not on the barrel or slide.