Geco 7,65x17SR (32 AUTO) questions

Hi to all!
I want to ask why 7,65x17 Geco rounds with the same appearance and headstams have nickel plated brass and nickel plated mild steel bullets? How I could define the time period of the cartridge production?
I attach some images for clarity.

These are nickel plated mild steel, brass, brass, and in that order they go further:

Cartridge weight: 7,52 gr (116,2 grains); 7,82 gr (120,6 grains); 7,70 gr (118,6 grains).



In my opinion, this represents use of the cheapest available material at the time. The cost of metals fluctuates. While all this cartrides have the same date code, remember that date covers a full year of production. That can represent dozens of lot numbers (different runs) in a common caliber like 7.65 mm Browning. This is commercial ammunition, so some of the ammo could have been a contract for a spedfic seller who specified bullet jacket material.

I am just curious, how did you determine that the non-magnetic nickeled bulletsx were brass, since they are plated? The norm for Geco is either gilding metal-clad steel, or plain gilding metal, that most of us usually just call “copper.” Geco has made some plain brass bullet jackets since WWII, alhtough I don’t recall seeing many, so I am not questioning the possibility that yours could be brass, simply wondering how you came to that conclusion.

Unfortunately, in the absence of lot numbers, and availability to the manufacturer’s record of the who, when, where, what and why of the materials used in each lot number, we can never REALLY know why you find variations in bullet material within the same year.

You can ID the exact year of production looking at the letters in the headstamp


Your rounds were made in 1965

Thank you for replying, my friends!

Firstly, I have about 10 of these rounds with same headstamps. They came to me from different places and people and in different times. I never have seen other headstamp of that manufacturer round here, in Bulgaria.

I determined the material of the bullets, because on a couple of these rounds at the nose of the bullet the nickel had weared out (by handling, I suppose), and the brass is clearly visible. The brass (70%-63% copper + 30-37% zinc) and gilding metal (95% copper + 5% zinc) have entirely different colors (orange and yellow).
There was a story, that somewhere in the Eastern Europe a factory had manufactured fake Geco rounds, but I’m not sure from whom I heard that story.
These cartridges here, in Bulgaria was used for AP (АП) - Hungarian copy of Walther PPK (I suppose).

And thank you for timing of the manufacture ID picture; quite usefull!



Geco, of course, is very well known all over the world, not just in Europe. Thank you for explaining how you
determined the bullet jackets were CN-plated brass jackets. Yes, you are of course right, brass and copper jackets are very different in original color. However, sometimes on older ammo, the brass darkents and it becomes harder to tell the difference. Oddly, the opposite is true as well. So older rounds not in mint condition have the brass change the tone of the color slightly to a point where it looks even MORE like brass.

There were somewhere around 15 years where Geco used that symbol-code for the date. Of course, commercial ammunition is not usually dated for sales reasons, and when it is, it is often coded some-how. People who are simply gun owners but not well versed on the subject have an odd idea about the logevity of quality ammunition, and won’t buy old stock if they know it is old. I have met customers who thought that if ammo was over 6 months old, it probably was untrustworhty, and if several years old, that it might “blow up their guns.” Of course, most of us here have probably fired ammunition as old as 40 and 50 years, or even more, that performed perfectly in every respect.

The story of fake Geco rounds is entirely true. Hungary produced some ammunition with “Geco” headstamp and
Geco’s date code as well, in caliber 9 mm Parabellum. They also made a box of Geco’s pattern, but the cardboard was of thinner, poorer quality than any Geco box, and some of the terminology on the box was unusual for German ammunition. I have this box and a cartridge in my own collection. This happend during the Communist rule of Hungary. Staff officials at Geco denied any knowledge of the ammunition, and it was felt that they were probably telly the truth. I was told that they were quite upset with it when they found out about the ammunition.

There was also some 7.65 mm Browning ammunition made to resemble Geco. It was made by Hirtenberg and sole in sterile boxes in South Africa during the world-wide embargo on that country years ago. The headstamp was “* GeO * 7.65” (The “GeO” is just as I have typed it here). At quick glance, the mind wants to tell the yes that they have seen “Geco,” even though it is not a true copy of the Geco name. It was certainly made to deceive, however.

The box for the ammunition for RSA proved an excellent example of why it is good to get the entire box, and not have friends tear of just the label to make them easier to mail. I ask a friend in RSA not to tear labels off, but rather to send the whole empy box. He couldn’t see any reason for it and I told him that sometimes box construction was unique to certain manufacturers. He sent me the absolute sterile “GeO” box with the challenge to identify the manufacturer. He picked the wrong box. It ias an exact miniature of a 9 mm Para box in my collection. labeled from Hirtenberger, and of a box design that no other manufacturer used! Before that, the “GeO” headstamp was “unknown.”

Is anything known about decoding Geco (Karlsruhe-Durlach) lot numbers?
The RUAG people I contacted simply said they had no documents regarding Geco lots. Quite possible I asked the wrong people.