Checking for Corrosive Primers

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   After 10 days in the humidor for the WLR, DI’43 and DAC’51 and 4 days for the DAC’45 and WRA ‘49 primer samples, I did a final inspection of the steel test sheet.  There was no significant change in condition as to compared with the condition after 24 hours. 
Corrosive primers do their damage within 24 hours in ambient humidity of 60%.  

Here is the test sheet just prior to cleaning with Hoppes 9.  A reminder that the light surface rust on the left side of the sample was from the water I sprayed into the humidor while the sample was in there. 

And on the opposite side, the WRA ‘49 Boxer Primer, visible pitting and some surface corrosion. 

I then cleaned off the primer fouling with Hoppes 9 on a patch. Only a very slight trace on the DAC ‘51 sample remains, the others are clean. 

And the opposite side, WRA ‘49 Boxer primer, dark corrosion and pitting remains:

So, not all Berdan primers used in WWII and later are corrosive, these examples are not. The 1949 WRA Boxer primer is quite corrosive, and this was after just one round fired. 

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britrifles Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: February 03 2018 Location: Georgia, USA Status: Online Points: 8404	Post Options Post Reply Quote britrifles Report Post Thanks(0) Quote Reply Posted: January 28 2026 at 4:14pm
	After 10 days in the humidor for the WLR, DI’43 and DAC’51 and 4 days for the DAC’45 and WRA ‘49 primer samples, I did a final inspection of the steel test sheet. There was no significant change in condition as to compared with the condition after 24 hours. Corrosive primers do their damage within 24 hours in ambient humidity of 60%. Here is the test sheet just prior to cleaning with Hoppes 9. A reminder that the light surface rust on the left side of the sample was from the water I sprayed into the humidor while the sample was in there. And on the opposite side, the WRA ‘49 Boxer Primer, visible pitting and some surface corrosion. I then cleaned off the primer fouling with Hoppes 9 on a patch. Only a very slight trace on the DAC ‘51 sample remains, the others are clean. And the opposite side, WRA ‘49 Boxer primer, dark corrosion and pitting remains: So, not all Berdan primers used in WWII and later are corrosive, these examples are not. The 1949 WRA Boxer primer is quite corrosive, and this was after just one round fired.

Shamu Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Logo Designer / Donating Member Joined: April 25 2007 Location: MD, USA. Status: Offline Points: 20510	Post Options Post Reply Quote Shamu Report Post Thanks(0) Quote Reply Posted: January 29 2026 at 11:09am
	Nice research. well done!
	Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)