To be honest, Tone.
I wasn't really comfortable with a 300 gram piston flying around in such a lightweight gun as it goes against everything we know on recoil and surge.
276grams I can live with, and with having to fit a bronze piston head and steel piston liner to correct the piston there isn't really any way of shaving much off that figure unless I machine a new head from Aluminum, which I won't be doing now.
Anyway, this morning I totally stripped the action and took the time to drill and polish the transfer port properly at 3mm.
Then I cleaned out the cylinder and transfer port and cleaned the piston, that's when I noticed a little problem, the piston head had a mark all around it's edge where it had hit something at the end of the cylinder --- so I had a look in the cylinder. :-
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There was about a 1mm wide ridge sticking up on the outside of the plug that coincided with the witness marks on the piston.
After thinking about making a tool to slide in the cylinder to take the ridge off, I said bugger it and machined the 1mm ridge from the front face of the piston --- job done.
Relubed and reassembled at my original 276 gram build with just 1mm of extra preload using all new seals again I fired a few Superdomes over the chrono. :-
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Hobbies are still doing 11.6 so that'll do for me.
As is normally the case on my last buildup of the trigger unit I discovered something that makes reassembly easier.
I've been struggling to get the trigger blade pin back in every time I've built this gun up and even altered a pair of pump pliers to assist in crushing the trigger spring, well this morning I realised what the unused hole was for between the stock bolt hole and the cocking lever slot.
If you stand the action upright on its backend you can push down on the sliding sear with a screwdriver to get the trigger sear hole in the middle of the window in the action. :-
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While holding the sliding sear down you can then insert a 3mm (or larger) drill bit into the forward hole to hold the sear in the cocked position.
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Then you can fit the trigger without struggling.
So that's it, I'm done and dusted with this one even though I could go further I'm calling it a day on my Original 35 --- what fun it's been.
All the best Mick