Thanks!
Yes, cold blueing with 5 or 6 coats of SuperBlue! In fact, I remove rust, pits and scratches, and I reblue all of them and all parts that need it, even the ones that just show excessive wear. (I'm now going to reblue them with a mixture of SuperBlue and PermaBlue in the hopes that the cold blueing will last longer.)
Also, I break all of them down as much as I dare to clean them and work on all of the parts that need work, even the slings. And some of the guns I buy are cheap because of missing or broken parts which I can fix or replace. And because I like recycling, most of the recoil pads, scopes, scope mounts are used.
That may sound like a lot of boring work, but I'm having a ball doing it.