As seems to be common with these guns the bolts that secure the barrel to the frame were made from cheese and cross threaded. Luckily the allen heads weren't rounded and the female thread seems to be ok, its just the bolts are unusable so need to be replaced.

I googled it but cant seem to find out what size they are and whether they can be replaced with off the shelf bolts, or am I going to have to buy two overpriced bolts from Chambers?

Thanks, Mark