With a little fitting, any period HP barrel will fit. I made the mistake of loaning mine out to a fellow that shot corrosive ammunition through it. When I got it back, 3 weeks later, the bore was a sewer pipe.
I searched for over a year for a new replacement bbl, made by Inglis. No such luck. Not even the friendly REME could find one. Then he told me they were replacing them with Belgian made barrels. It did require a minor amount of fitting but that was it. I'm still looking for a proper replacement bbl and still have the original. Lack of parts for these pistols is one of the reasons the Canadianmilitary is slowly phasing the HP out. AFAIK