Actually Halco, which is the he J. Halpern Company of Pittsburg, Pennsylvania was/is a huge 'distributor' of Cap Guns. They distributed millions of Cap Gun Pistols made by 'other' companies. So when you see a 'Diamond H' on a Cap Gun, you know it was distributed by HALCO, and not made by HUBLEY.
Please read my other Ebay guide on 1950's Cap Gun Identification. If you think this information was helpful, please click the 'yes' button below. Thank you, TheBreezeHouse