Need help finding a bolt for my HW50S

When my HW50S started to make metal on metal noises I tried to take the stock off to locate the problem. Problem is I wrecked the head of the bolt . When I return from holidays I’ll be returning it to the gun shop for repair but I’m going to need another bolt. I still haven’t removed the stock as I will void my 3 year warranty, It’s the one at the front of the trigger guard. Does anyone know where I can obtain one or what size the bolt is. I’ve contaced Weihrauch but no response.

Many thanks

Gary