Have you tried a Lee Decapping die?
You cannot break the pin if you get a real tight primer then it will just slide inside itself and all you have to do is reset the pin. Lee has a universal die PN 90292 around $10 or you can get a complete carbide die set PN 90602. This would in my opinion be a better solution than trying to find a soft carbon steel nail the right diameter to wreck you cases or die.
I bought my Dies from
http://www.fmreloading.com you could also try
http://www.midwayusa.com