Have you documented the gains in such work? Lightening pistons and transfer port modifications are way above my understanding.
What type of muzzle energy are we talking on the 80?Yes mate
Adding the delrin buttons/bearings removes the metal to metal contact. My 99 like most had the galling problem from the poor design of the cocking arm . With this modified I decided to do the piston , you can see the witness marks on the pistons where they pick up on the cylinder. Hw pistons are slightly flared on the rear skirt to act like a bearing, you remove this so the pistons are straight then add the synthetic bearing so they run on that . It’s makes the cocking much smoother, keeps everything central, and you only need a fraction of lube . I use ws2 powder mixed with stp/ petrol additive as a lube a tiny amount behind the seal and same for bearings. On the 99 there was a small gain fps I recall 6 but a huge gain in smoothness and shot cycle .
Opening up the transfer port was done on the 80 because the piston is so light 3.4mm was the final size tuned for jsb pellets . That’s a very nice rifle to shoot .
It’s 12fpe buddy I’m from England we have to modify to balance things out . The 80 can do 20+ better around 16 you could add the same type of piston bearing but wouldn’t need to lighten the piston , and I’d use a steel or phosphor bronze rear guide fixed into the trigger block .
Yeah that's a bit ridiculous. Out of curiosity why go with an 80 at all over lets say a 35 if you're limited to 12fpe?
Short answer is I like them they are very popular in the uk and sell well , the mk1 is the most sort after.
I fitted the hw98 barrel shroud ove the 16 inch barrel, you can swap barrels but I only had the shroud. And a cs500 stock
Yeah Steve,
Yes I’ve seen Jim’s buttons on his web page . If you ever get an old piston try the drill and tap method its pretty easy
What's the drill and tap method?Yes I’ve seen Jim’s buttons on his web page . If you ever get an old piston try the drill and tap method its pretty easy
Sizes are in metric mate
That's what I was thinking but wasn't for sure. I thought most people just used a 4 flute center cutting end mill and plunge into .020 or so, then glue in a slice and then turn it down. I guess there's more than one way to getter done.Sizes are in metric mate
I used 6mm delrin rod . Run a m5 die down the rod to create a thread .
Drill 5mm holes in the skirt of piston and thread with a m6 tap . Locktite the threads and screw in .
Remove the protruding threads from inside of piston until flush.
The turn down the buttons until you have a nice sliding fit to the cylinder
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Yes if doing a comp tube that’s the way . Paul watts got some great videos, clever bloke brilliant work
Ring bearing would work if you only have a lathe.
