I thought I would pass along an interesting article on this subject:

Mercury, Potassium, Lead: Do Corrosive Primers Harm Brass?

Not sure how relevant this information may be these days, but I, for one, still have quite a lot of near-ancient, once-fired brass in a number of calibers.

Potassium chlorate primers have been and still are used in some ammunition, particularly military ammunition made in "out of the way" countries. It is a dependable priming compound but is corrosive to steel.

Fulminate of mercury does attack brass, but to my knowledge it hasn't been used in small arms ammunition for quite a long time -- likely longer ago than any cartridge cases you might be considering were manufactured.

So far as I know, commercial ammunition made in the U.S. from WW-II onward has used lead styphanate as its priming chemical.

early 50's was the last I know of for some military ammo made with corrosive primers.

bet there's still some floating around out there.

Mike:

When the fulminate of mercury in a mercuric primer detonates (same stuff is in blasting caps, or was), metallic mercury is a byproduct. During the 19th century, with black powder as the only powder, the mercury was contained within the black powder fouling, and washed out when the case was cleaned before reloading. With the advent of smokeless powder, the mercury was deposited on the inside brass surface of the cartridge case, thus weakening the case. Mercuric primers haven't been used in probably more than a century, except for a few special lots of military match ammunition in the 50s.

Potassium Chlorate it the culprit in corrosive primers. When the potassium chlorate in the primer detonates, potassium chloride is liberated. Potassium chloride salts absorb moisture, thereby "corroding" whatever steel they are on. Potassium chloride (KCl is the dietary salt, No Salt, meant as a replacement for common table salt, Sodium Chlorids NaCl).

Lead, Barium, whatever else replaced potassium chloride as the priming agent in the 1920s or 30s in most US commercial ammunition, to make non corrosive priming. You have Winchester Staynless, Remington Kleanbore, Peters Rustless, other brands all had similar clean non rusting names.

Sooooo, black power priming was mercuric and corrosive, but it wasn't a problem. Early smokeless priming was also mercuric and corrosive, and it was a definitely a problem with both with bores and brass. At first smokeless powder itself was blamed for this.......... Then, in the oughts and teens mercury was removed, and just corrosive priming remained, easily cleaned away with water. Most commercial ammunition went to non corrosive priming in the 20s to early 30s or so. The US military finally followed suit in the early 50s for the most part.

Now foreign ammo, that's a different story, I'm reminded of the 7.62X39 Russian steel cased ammo that was "mildly corrosive"!

Enough with the chemistry lesson for today.............

Thanks, all, for the info.

I found this good resource on the subject of military non-corrosive vs. corrosive ammo put together by the CMP.

U.S. GI Non-Corrosive Primers

I have a fair quantity of 30s and 40s vintage M2 Ball once-fired cases that I picked up at an estate sale and I am going to donate them to the scrap heap at my gun club.

Just out of an abundance of caution.

On the other hand, I also got a lot of FA, TW and LC brass from the mid- to late-50s and on into the 60s that I will keep.

A lot of it is match brass, so the primers aren't even crimped.

Good stuff.