Noncorrosive primers finally became standardized for the US military in 1949, and by 1950 all US military small arms ammo, including newly manufactured M2 Ball (and that was our original question, wasn’t it?) featured nonchlorate and non-mercuric primers, according to former NRA Technical Editor E. Harrison, whose experience working with the Army’s Ordnance department give his statement credibility.
The Ammo Encyclopedia (6th Edition, 2017, Michael Bussard) has information slightly differing from Harrison’s, stating Frankford Arsenal utilized chlorate primers “until the mid-1950s.” Another researcher has done us a service in publishing a paper that specifically identifies noncorrosive US manufactured military ammunition from WWII to 2001, including .30-06, 45 ACP and 7.62 NATO, by lot number and date; a free, downloadable PDF is online at: odcmp.org/1101/Citing yet another exception to the 1950 rule, apparently no US military issue 30 Carbine ammo was ever loaded with corrosive primers.However, a generous quantity of liquid media should provide enough dilution to carry away the salts and work quickly enough to prevent dezincification.Still, if you don’t like the idea, you might clean in a dry media tumbler those fired cases that had been loaded with corrosive chlorate primers. Theories aside, the reality is that I’ve never heard of any documented failures of cases previously fired with chlorate primers that had been cleaned by either dry or wet methods – that is, failures inarguably attributable to chlorate primers—so reloading such cases after cleaning is apparently a nonissue in that regard.Exposure to saltwater weakens brass by “dezincification” where the zinc is lost (think of it as being dissolved out), leaving the copper porous (think of a colander) on a molecular level.
Logically then, we might think it a bad idea to clean cases in a liquid media which, when mixed with the fired primer’s chloride, would create a saltwater mixture.Again, especially in humid climates, it is important to clean immediately after a session of shooting with potassium chlorate primers.But this isn’t typically possible in a combat environment, so the military’s search for a non-hygroscopic replacement for potassium chlorate was on soon after they hit the streets.By Art Merrill | Contributing Editor Here’s a question handloaders end up fielding now and again: “Is it OK to reload brass that originally fired corrosive primers?” Most recently, the question posed to me was in regards specifically to military surplus M2 Ball .30-06 brass.Because of the potential for case failures, firearms authorities have long advised against reloading cases that originally fired mercuric primers, even though reloading them was a practice of necessity for many in the early days of metallic cartridges.