The first Independence 9 mm cartridges were made by CBC of Brazil. I believe they were sold through Speer/CCI as a separate brand, and not thru Magtech, but I could be wrong on that. Of course, the aluminum case version with the standard “N R” style headstamp, but with CCI replaced at the top by I were made by CCI. The Brazilian loads are immediately recognizable by the primer marking, a flat bottom version of the letter “V”. Of course, if you have the box for them, it is clearly marked made in Brazil, just as the later boxes are marked made in the USA.
As for the later brass-case Independence loads of America manufacture, I am not sure who loaded them, but there was more than one brass supplier. Some of the cases were made by CCI, headstamped “I 9 mm LUGER” with the shape of the “9” and the “R” probably indicating they were made on their Formax machinery line.
Then, the is the headstamp " I 9MM LUGER" which looks like it might be in a case made by Federal, part of the same ownership group as CCI/Speer. These have a copper-plated bullet, probably of the “Total Metal Jacket (TMJ)” variety, which could indicate loading by Speer-CCI, or bullets supplied to Federal by Speer/CCI for their loading.
The final headstamp is " I •9MM LUGER" and is the only one with a case cannelure. This cartridge has the appearance, from top to bottom, of Federal Production, with a standard GM FMJ bullet.
These ID’s are purely based on the appearance of the cartridges and their headstamp fonts. I don’t know who made the cases with the dot before the caliber marking, but they look like Federal Headstamps.
I have other Independence calibers, but didn’t want to turn this reply into something too long and complicated, because the 9 mms are typical, and I don’t have any better information on the other calibers. All of mine are auto pistol only, as I don’t collect revolver calibers.
Hope this is of some help, and perhaps inspires someone with a little more “inside information” to respond.