Brass Tarnish - Dangerous?

[Mickey the Dragon]

I recently purchased over 300 cases for my 45-70 and they all showed up with various levels of tarnish on them. Most of them just have a few brown spots on them that clean off pretty well after a night in the media tumbler with crushed walnut. However, about 30% of them have some very slight pink spots at the base of the case, right where the rim meets the body of the case. Should all of those just be pitched? I can post pictures if that would be helpful, but the pink spots are so small that the camera might not pick them up.

 

[j8064]

Brass will tarnish. As long as there's no corrosion or metallic breakdown the case in the pic looks good to me.

 

[Mickey the Dragon]

Here's a fancy picture, this time I used the flash.

 

[BradMacc82]

I don't see anything obvious that would cause concern...

 

[Streetgang]

Pink is an indication that the zinc has leeched out of the brass to leave copper. If it polishes off then it should be no worry. If it doesn't polish off then you've got a pocket of copper in your brass casing. Copper without zinc is softer and won't hold up to the pressures of shooting as well as that of intact brass.

What you decide to do with this information is completely up to you. I'd be wary of using it personally.

 

[BradMacc82]

Pink is an indication that the zinc has leeched out of the brass to leave copper. If it polishes off then it should be no worry. If it doesn't polish off then you've got a pocket of copper in your brass casing. Copper without zinc is softer and won't hold up to the pressures of shooting as well as that of intact brass.

What you decide to do with this information is completely up to you. I'd be wary of using it personally.

Learned something new.

Good info.

 

[Streetgang]

Learned something new.

Good info.

I'm an old dog... Wifey taught me to sit today...

 

[BradMacc82]

I'm an old dog... Wifey taught me to sit today...

Ha. I'm single, so just barely house-broken.

 

[Mickey the Dragon]

Well, I hit it with a stiff brush and the irksome pink tarnish came off and didn't appear to leave any pitting. I'm going to go ahead and reload it and let you know if it blows up.

 

[outrider58]

Well, I hit it with a stiff brush and the irksome pink tarnish came off and didn't appear to leave any pitting. I'm going to go ahead and reload it and let you know if it blows up.

Send us a pic if it does.

 

[DocAitch]

The 45/70, being originally a black powder cartridge, is a low pressure round.
http://www.saami.org/specifications_and_information/specifications/Velocity_Pressure_CfR.pdf
Peruse the SAAMI chart and you will see that it has significantly lower pressure than modern rounds.
I would not advocate unsafe or sloppy loading practices, but you do have a bit of lee way with this round.
DocAitch

 

[somd_mustangs]

Pink is an indication that the zinc has leeched out of the brass to leave copper. If it polishes off then it should be no worry. If it doesn't polish off then you've got a pocket of copper in your brass casing. Copper without zinc is softer and won't hold up to the pressures of shooting as well as that of intact brass.

What you decide to do with this information is completely up to you. I'd be wary of using it personally.

Excellent point.... I don't know about cartridge cases but with brass instruments (trumpet etc) this pinkish-reddish color is a sign of the deadly "red rot" or "brass rot". It occurs from inside out and by the time you see it on the outside, the damage is done and there's usually a pinhole (possibly near microscopic) at the center and a fair amount of corrosion on the inside. You can clean it off the outside but the brass tubing will be very weak. It takes a good long while to form though.

These cases are probably fine but if at all possible also check the inside of the case carefully for signs of pitting & discoloration.

 

[Jimdick2949]

Better safe than sorry.

 

[outrider58]

Better safe than sorry.

Roger that!

 

[shaddydan]

Good info all the way around! I honestly never even gave the pink a second thought, I guess I will have to inspect my brass more cautiously now.

 

[Combloc]

I've shot 30.06 that looked like it came from the bottom of the Pacific! That brass is fine.