Yes we can go round and round on this all day and night. Theories are: Investment Cast [IC],,Die Cast [DC],,Struck,,Pressed.

Tell you why I don't go for the Investment Cast. I've seen an HR badly damages. Craig you have also, as you did a great job restoring a HR.. Well the one I got to study the inside just did not look like investment cast? *Investment cast pieces whether now or long ago have a certain look to them inside and this HR did not have it.
*Another reason,,super worn rings. Unless modern methods of IC [investment cast] when an older IC ring gets really worn you will come across a pock mark, a dot, a pop. I've seen many worn rings and never seen one display anything eve close.
* Another and its is a common sense thing,,IC is just to long, too many steps, too many different tooling/manufacture pieces for the method.
*and last,This might not matter to many,,but years ago I saw something. That something was explained and ever since that day I believe Don fully. No I can not say what I saw. There are 6 or so that I heard of that have seen it too and the all of us made our promises first.

* and finally,,I've been collecting Private Purchase rings since the mid 1970s. I have a solid 10 years collecting info for a book I've been working on. Everything I've seen, had translated, interviews, and own a few pieces of original tooling,, the PP rings were not IC and made in the flat. I own many rings more complicated than the HR and there would be no reason why the Gahr firm would deviate, it is just the way it was done back then...
We have a nice topic pinned to the top about a supposed method of making the HR but I firmly believe it is a little more/different than what is shown but the basic idea is there.

none of us were there, so in the true meaning of our 'forum' we will not suppress anyone's theories/beliefs and all are welcome.
I just ask anyone posting to please add why or why not you believe what you do.. thanks , G.