ericp
.327 Meteor
Posts: 505
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Post by ericp on Oct 18, 2016 9:28:27 GMT -5
Through work I have access to a pXRF (portable X-Ray Fluorescence) gun. This device zaps a sample with x-rays which causes the atoms of the sample to fluoresce at different wavelengths which the gun then measures to tell the user what the sample is comprised of. I use this thing for measuring soil samples at former industrial sites.
I've tested four different copper cartridge cases so far including a 50-70 (with the nifty internal bar priming), 2 22 Shorts, and a 41 Rimfire Short. All of the limited number of samples gave a reading of roughly 2% zinc. Extremely pure copper was available in the 1860s from the native copper mines of the Keweenaw Peninsula and I do not think zinc and copper occur together naturally suggesting this is an intentional alloy. For comparison, modern gilding metal for bullet jackets is 5% zinc-95% copper and cartridge brass is 30% zinc-70% copper.
So metallurgists, what is gained from 2% zinc? Is that enough to have a noticeable effect on the "spring" of the case or reduce corrosion? Something to do with drawing the cases perhaps? I'd love to hear people's thoughts on this.
Eric
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ryan
.30 Stingray
Posts: 402 
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Post by ryan on Oct 18, 2016 10:14:49 GMT -5
You lost me at "causes the atoms of the sample to fluoresce"...  |
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JM
.375 Atomic
Posts: 2,425
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Post by JM on Oct 18, 2016 10:35:34 GMT -5
I had a Black Light once...
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Post by bradshaw on Oct 18, 2016 10:56:20 GMT -5
Through work I have access to a pXRF (portable X-Ray Fluorescence) gun. This device zaps a sample with x-rays which causes the atoms of the sample to fluoresce at different wavelengths which the gun then measures to tell the user what the sample is comprised of. I use this thing for measuring soil samples at former industrial sites. I've tested four different copper cartridge cases so far including a 50-70 (with the nifty internal bar priming), 2 22 Shorts, and a 41 Rimfire Short. All of the limited number of samples gave a reading of roughly 2% zinc. Extremely pure copper was available in the 1860s from the native copper mines of the Keweenaw Peninsula and I do not think zinc and copper occur together naturally suggesting this is an intentional alloy. For comparison, modern gilding metal for bullet jackets is 5% zinc-95% copper and cartridge brass is 30% zinc-70% copper. So metallurgists, what is gained from 2% zinc? Is that enough to have a noticeable effect on the "spring" of the case or reduce corrosion? Something to do with drawing the cases perhaps? I'd love to hear people's thoughts on this. Eric *** Eric.... thanks for the info. Perhaps readers will supply you samples of old copper cartridges for analysis. Reportedly, early copper cases had no springback, and inclined to stick in the chamber. perhaps some of the copper cases contained no zinc at all. David Bradshaw |
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Post by BigBore44 on Oct 18, 2016 12:14:20 GMT -5
You lost me at "causes the atoms of the sample to fluoresce"... You & me both  Interestingly weird stuff... I did however eat at an IHOP once  BigBore44 |
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Post by magnumwheelman on Oct 18, 2016 13:39:20 GMT -5
I would think Zink would harden the copper... perhaps causing less case sticking through "bounce back"... I don't think it was for preventing corrosion... I also don't think the addition of Zink would aid in drawing the cases... I would suggest it would increase the tinsil strength, allowing either higher pressure or possible reloading??? or the strength needed for the use of an extractor
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ericp
.327 Meteor
Posts: 505
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Post by ericp on Oct 18, 2016 16:38:45 GMT -5
Through work I have access to a pXRF (portable X-Ray Fluorescence) gun. This device zaps a sample with x-rays which causes the atoms of the sample to fluoresce at different wavelengths which the gun then measures to tell the user what the sample is comprised of. I use this thing for measuring soil samples at former industrial sites. I've tested four different copper cartridge cases so far including a 50-70 (with the nifty internal bar priming), 2 22 Shorts, and a 41 Rimfire Short. All of the limited number of samples gave a reading of roughly 2% zinc. Extremely pure copper was available in the 1860s from the native copper mines of the Keweenaw Peninsula and I do not think zinc and copper occur together naturally suggesting this is an intentional alloy. For comparison, modern gilding metal for bullet jackets is 5% zinc-95% copper and cartridge brass is 30% zinc-70% copper. So metallurgists, what is gained from 2% zinc? Is that enough to have a noticeable effect on the "spring" of the case or reduce corrosion? Something to do with drawing the cases perhaps? I'd love to hear people's thoughts on this. Eric *** Eric.... thanks for the info. Perhaps readers will supply you samples of old copper cartridges for analysis. Reportedly, early copper cases had no springback, and inclined to stick in the chamber. perhaps some of the copper cases contained no zinc at all. David Bradshaw If anybody has old copper cases laying around they are willing to ship, I'll test them and ship them back. David, I've read about extraction problems relating to the lack of spring back in copper cases as well, all of it pertaining to large cartridges in singleshot rifles like the 45-70 in Trapdoors, etc. Can't recall it being mentioned as a problem with any of the less potent repeating cartridges like the 44 Evans, 44 Henry Flat, or various Spencer designs though. This is not to say my search has been particularly thorough, just what I can remember from casual reading. More research is clearly needed. The Battle of Little Bighorn stands out as an example of the former in my mind with many reports of Trapdoors found with cartridges jammed in place with the rim torn off and one officer who had a rifle instead of a carbine moving around the battlefield offering the use of his cleaning rod to punch out empties. magnumwheelman, Could well be a simple matter of a bit more strength to aid in extraction, pure copper if awfully gummy stuff and I could see it being problematic with folded head case construction. Eric |
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Post by cas on Oct 18, 2016 18:01:11 GMT -5
You lost me at "causes the atoms of the sample to fluoresce"... It's like, beautiful man. |
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petep
.30 Stingray
Central Alabama
Posts: 453
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Post by petep on Oct 18, 2016 18:11:51 GMT -5
I guess it all depends on where that original copper came from.You speak of the Michigan native copper and yes that copper is very pure but other copper deposits depending on the geology could contain copper,lead and zinc along with a host of other elements.Google up Antamina Copper-Zinc Mine, Peru and you will see what I mean.I may be wrong but it is hard to believe that zinc was alloyed with copper at that low a percentage on purpose.
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sal
.30 Stingray
Posts: 315
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Post by sal on Oct 19, 2016 0:24:32 GMT -5
how many flapjacks does it take to cover a dog house ? Six,because ice cream doesn't have Bones!
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