How bad was the breech mechanism, and what procedure did you follow when working to free it up?
He exaggerated a bit, the mech was frozen solid was what he meant to say. The mech was designed so there wasn't much room for rust really. I think there was enough original grease in the parts so it took many years for the oxidation to begin. Parts may have been blued or browned also originally, hard to tell now.
I hate to reveal trade secrets of course, but to free up anything, the very best way of all is to dunk the whole thing in an electrolysis vat and cook it there for the prescribed time. The vendors with facilities to do that enclose the whole thing in a chickenwire (or whatever it is) cage, then lower it in with a crane and turn on the juice. That gets the oxidation out from between bolt threads and anything else, like magic. Take it out and everything works.
Since that wasn't possible here, I used more traditonal techniques which include penetrants, impact (vibration), reversing motions, etc. Penetrants are getting better all the time, way back the best was Kroil or Silikroil, then Break-Free was good (still is) and now one called "PB Blaster." This stuff actually seems to be able to dissolve rust to a certain extent. You get this pungent-smelling stuff at auto supply stores. Here's an ad just so you can recognize the can:
http://www.bizrate.com/automotivecare/products__keyword--blaster+penetrant.htmlHeat is great too, heating and cooling, and injecting penetrant so the cooling sucks it into small spaces. That wasn't possible here.
Impact works wonders and works the penetrant in to small spaces. Impact causes vibration at high frequencies and does good work on stuck things.
Whenever you are workiing with stuck bolts or rotating things, never just torque it on one direction, go back and forth in both directions (be gentle in the "tightening" direction of course.) Don't argue and don't ask why, just do it.
One thing that seems to help on rotating things is to scribe an index mark on both parts so you can tell the instant it starts to move, and in which direction it is moving. Then you can keep doing whatever you were doing when it started to move. This sounds dumb but believe me when you spend an entire day trying to get one shaft to turn a little, you'll want a scribe mark on it.