I bought a brand new R10 Mk2 that had problems right from the off so back to BSA it went.
It came back with a note saying it had had a different Reg and Internals fitted.
It still wasn't fixed so back it went to BSA again.
They fitted ANOTHER Reg (3rd one in total) and this time all was well with the gun but, having lost all faith in the R10 at this stage, I traded it in.
Won't be buying another BSA again.