The problem usually isn't with retired gunsmiths that have a beat up V that they understand the limitations of thowing money at, rather, otherwise sane people, who have the ONE example they have ever seen in their hands, and making the decision they are somehow qualified to work on it, with the toolset they got the wife for Christmas, the toolset with the pink handles.
It doesn't seem from this point that you are the latter, but, trust me, I have met them, way more times than I care to remember.
It does take substantial effort to get the key up and out of the sliding breech on a V. Make sure you are straight up in the air with it, and keep tugging. It likely has some crud about the axle, and you are forcing that crud out from between the main spring and it's interference fit with the axle. It will be easier to do, the second time you do it.
Good luck. I'd make an effort to replace any screws that are missing, they all have a job to do on a Darne.
Best,
Ted
