Hey there Ant,Can the owner take it out and shoot a few boxes of shells through it and then have you check to see if it loosened any?
Maybe some jarring during shooting my loosen it up some. Or possibly over time the penetrating oil that is still in there might do it's thing.
I have heard from some gunsmiths that using some acetone and penetrating oil together works. You need to keep it away from the wood finishes, and something about putting aluminum foil around the area so it does not evaporate too quickly. Supposed to thin out the oil to get it in to tighter areas.
I know nothing really about that, but it is something that I heard before. It may even be that the new penetrating oils already have an acetone type solvent to assist in penetrating.
Just trying to help come up with some ideas. But take my gunsmithing advice with a grain of salt and lime.
I know it has to be frustrating and sitting in the back of your mind that you were unable to fully disassemble it because of that crazy stuck pin.
I know it would be bugging me that I could not get it out to do a complete job.
Yes, very frustrating. Especially since I have the exact same gun and mine comes apart easily. Oh well, I gave it back him. He said that it's greatly improved so that's a start. I'll keep you posted if it ever comes out.
Thanks for the tips,
Mc