.505 Gibbs Rifle Brass 'H H' Headstamp: Maker and Quality Info Sought

Question: 

I acquired quite a supply of .505 Gibbs brass about six years ago and hadn’t looked at it in some time. Recently, I asked a buddy (that I trust) to handload some of the rounds. I thought, by memory, that they were Norma and Bertram brass, but he said that many were headstamped “H H”, and that he had gone ahead and loaded them. He was unfamiliar with this branding and thought I ought to check. I have now consulted several references, and cannot identify the “H H” head-stamp. Can you help me identify the maker and quality of this brass? It appears high quality, but before I touch one off, I’d like to be a bit more certain.

 -B.K. via Email

Answer: 

This one’s a real poser. I checked every reference I have and had a couple of friends familiar with unusual ammunition do some research as well. We all came up empty. After spending quite a bit of time on this one, I am curious myself as to what the “H H” might signify. I’ll throw this one out to Guns & Ammo’s readers. They’ve always come through in the past. 

-Garry James