well.. i have been searching for hop up rubber, and bearing for my KSC Glock 19. (part no.14/16) I've found a few sites with these parts, but never in stalk. BUT i have found one site, Tokyo Hobby, which had them in stock. I also have a KWA Mac11, which i needed to dry out the over lubed hopup, so while it was out, i compared it to my G19 barrel/hopup. (i vaguely remember reading this somewhere.. but cant seem to find the thread, so sorry if i missed it, and this is just a repost).
THEY ARE COMPATIBLE!!! Baring and rubber were a direct swap in!!
That being said.. the barrels are not compatible, by the looks of it. (the part in the hop up unit.. i just didnt feel like taking it apart again)