The $100 challenge.....

I have the option of MIG or TIG.  I'm pretty average at both but manage to get stuff done.  I'll probably build it up with the MIG and put a blob where the shoe locates, then grind it all back with the belt sander first and then finish it off on the lathe.  

I think Kruza was right about the cone washer under the factory seal, that would definitely help absorb the shock from the piston.

Another afternoon of disappointment . Cleaned everything up, straightened the spring without too much effort, made up a slim steel top hat and a thin washer (the two together only about 20 thou thicker than the factory steel washer I removed), reinstalled the original seal and then applied a nice red assembly lube I had lying around that claims to have 3 times the scuff resistance of moly grease.  That's good enough for me and what's more, it must be fast because it's red!  Cocked it for the first time and the action was silky smooth - cool!!!  Then I decided to de-cock it and it dry fired even though I was holding the barrel, and after that it wouldn't latch.  Oops, something's not right for sure.  

I removed the stock and there it was right in front of me, the piston had disengaged from the cocking lever! (you can only just make it out amongst the grease in one of the photos).  How could this possibly happen you might ask?  Well, as embarrassed as I am to admit it, I'm a complete plonker and assembled it (and did so several times earlier as well) with the shoe between the cylinder and the piston.  I missed doing it as I compressed the spring and didn't even realize what I'd done as I was able to easily insert the shoe after it was together without noticing that I wasn't putting it into the piston slot!  What a dumb ass.  So, it was cocking against the raided outer edge of the piston, badly side loading it and gauging both the piston and the shoe. This certainly explains the issues I was having yesterday with metal to metal grinding and erratic shots.

The only way to sort out this immediate issue was a hammer to knock the shoe back over the piston into the swaged centre section so it could be removed.  Some more damage to the piston now, but again the cylinder has survived unscathed. It's a pity the piston wall isn't a straight tube with some minor skimming to created slightly raised ends, that would have made it almost impossible for me to do what I did.  I sure am learning about these things the hard way .

The next move now is to build up the piston with weld at both ends and also weld up the damaged slot end then machine and grind everything back to decent tolerances.  Ive started by cutting out the original weld on the lathe and removing the centre rod.  Tomorrow night, I start welding!