I can't remember, but it was either ammonia or vinager that was supposed to be rough on case hardening. I actually use a lot of the 409 windex, especially at a match. I use bore snakes too on SXS and on rifle. I let the pistols ride and don't have any problem with them in a 6 stage match. I don't have any case hardening anyway, but I thought I had heard that. :-)