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PostPosted: Fri Dec 28, 2018 10:25 pm 

Joined: Tue Sep 22, 2009 9:57 pm
Posts: 76
Location: Aurora, ON, L4G7X4
Seem to me the valve seal "back blows"? or how to call it...
HPA running about 1250 psi right now a target is 1500, and adjusting a hammer spring tension with a back screw mod.
(uhm, trying to add a picture to my story, load it from my HD, added a file, but not seeing it where it is now, hopefully will follow in next line)

20180130_220533.jpg [ 92.85 KiB | Viewed 547 times ]

Got a IR chronograph months ago but only these winter days got some serious time to sit down and play with full attention.
Slowly I was raising the speed from high 600s to 853 fps (18gr) when suddenly I started feeling the air pressure on my palm, perhaps through the breach block.
Over summer time I had several situations when I blow the port seal between the barrel and the block until finally I learned how to fabricate myself a custom thickness/softness seal so that "side blow out" effect finally stopped.
But this is now different...look like the hammer hits harder the vent shaft (because I am adjusting the hammer spring for highest velocity) and that spring (still the original if I could recall it) may be too soft and bounces (beside the fact there is a support pressure of 1250 psi)?
I can lower the spring tension a bit back it down to mid 700 fps but my target is 1500 psi anyway....
What may be missing here?
Is there a valve assembly better fabricated as the original built? with tighter tolerance on that 3mm or 1/8 valve shaft? I have seen some pictures earlier days before I even know how to open up this gun, but that was at least a year ago...
or shall I just try a harder spring load on the valve side
At lest I made this my toy easier to separate into parts...

20180825_142147.jpg [ 65.38 KiB | Viewed 547 times ]

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