After almost 5000 shots I decided it was time for a few little tweaks and modifications. I did not have a camera at hand, which is why the explanation is a little long-winded...
First up was the trigger. I have been shooting mostly offhand at silhouettes lately, and even with the pull set as light as possible, the second stage was still a little gritty and required more force to squeeze off than what I could manage without yanking the sights off-target.
I took the trigger apart one piece at a time, polishing contact areas to a mirror-finish. The u-section of the lower sear had worn two deep grooves where the trigger pins make contact, and I had to remove quite a bit of material before they were polished out.
One other thing I wanted to sort out with the trigger is the tendency for the first stage to lose spring tension after it is taken up for the first time. My guess would be that the friction between the sears is too great for the spring to overcome and the sears remain "stuck" at the end of the first stage. This then leaves the trigger blade completely floppy until second stage is taken up.
I then polished the culprit sear contacts and while testing the trigger on its own, it seemed to work. I could clearly see the sears reset after releasing the first stage. However, when I finally put everything back on the rifle for a test shot, the problem was back.
I think that the sharp edge that I left on the sear (it picked up a curly when I pulled it across my fingernail like some micro block-plane!) digs into the opposing sear, preventing it from sliding in one direction.
The second stage is much better now and I was able to shoot a few 10mm groups at 12m for the first time. Not great, I know, but not too bad for shooting offhand and with open sights either!
Next up was the cocking-link, another u-channel member that was digging trenches into the bottom of the receiver tube. It has a little slider wheel that is sitting too low in the channel to prevent the flanges from also making contact. The wheel is a loose fit on its pin but does not turn easily.
Having designed an aircraft wing spar from ali and earning some hard-won buckling experience (believe me, it was not pretty!), I judged this link to be a complete over-design and promptly ground away about 1mm from each flange. This ensured proper clearance all around, but that shoddy wheel still caused undue friction while cocking.
I then cut a stub of 8mm brass tube, slit it and fit it around the wheel. I wedged the bottom of the wheel, preventing it from turning so that the brass can slide. The effect was instant improvement, but the brass soon worked off the wheel and I was not ready to start gluing things in place just jet. I had one more solution to try - a half-moon shaped nylon block that fits over the wheel. Even better that the brass, as it turned out, smoother to cock and less effort required. So it will stay until it is worn through at which time I will replace it with Delrin or Vesconite.
I left the biggie for last - bedding the action. I read Blud's how-to in the technical reference section. It seemed like a horrible job but worth the effort. I must have changed my mind a dozen times between bedding the entire action with epoxy and cotton flocks, and only bedding a few select areas using pratley putty (the easier, less messy option).
I finally convinced myself, with Blud's encouragement, that if it is worth doing, it is worth doing properly. I started with wrapping the action in glad-wrap, but soon changed my mind and painstakingly mummified the action in masking-tape, but leaving as much bare metal as possible for a true mated fit.
I then rubbed some neutral kiwi shoe-polish on tape and metal as a release agent and got to work on the stock to prepare the mating surfaces. This basically involved scraping off any varnish with a course half-round wood file, leaving nice deep grooves for the epoxy to grip. Any adjacent areas on the stock that might get some epoxy on it once it starts to squeeze out was also covered in masking tape.
I had some left-over epoxy from a kayak project (AMT SP106) and mixed up about 25ml. I dabbed all the bedding areas on the stock with clean epoxy first, since the low viscosity will give proper penetration into the wood. I then added cotton flocks and wood flour to the remainder and applied the paste to the stock. I added a little more flocks for a firmer paste in areas where large gaps need to be filled, such as the gap right at the rear of the receiver.
The epoxy is curing as I am typing, so tomorrow will be the day of revelation! I will try and remember the camera for the remainder...