I live in the U.S. (yeh, I know, lol) and bought an ACM M500 for our son. He knows, as the dealer told us, that the "proud steel charging handle) break, because of poor quality metal used.
Well, have been looking all over for the part, with little luck. WGC does not have the part, and from emails I have been getting, do not anticipate getting the part.
I'd like to get it and replace before they break. The only place I may have found the item is at
http://www.fire-support.co.uk/category.php?cat=278, and I'm waiting for a reply to see about shipping to the U.S.