As mentioned in an earlier thread, I contacted UKgunworks about producing a replacement unit for the above rifles. I have been advised that the cost will be circa £185-195 each, and that I will need to come up with a list of 15 people to make the production costs viable. They are also hoping to locate a better quality magazine to replace the original.
I haven't had any dealings with them previously, so any feedback would be useful. Let me know if you are potentially interested.