Probably way off the mark but that HH logo is similar to the one used by Helly Hansen who are an old Scandinavian company specialising in heavy duty outdoor clothing, originally for the fishing industry. They may have decided at one time to offer other products that woud tie in with their outdoor and sports lines? Trade marks are well protected and using anothers would cause trouble?
The second thought is that the owner decided to put his initials on the pistol. The BSF is a fine air pistol, after all