the vavle on these is huge - around 8mm. S0 it creates a lot of pressure on the valve stem, whcih changes with fill pressure.
hi fill pressure = very hard to open, not much air, low velocity.
as pressure reduces, valve opens easier, lots more air flow = hi velocity
All PCPs do this to some extend -0 that's the power curve. However yours seems extreme..
Here's (generally) how to sort it (as every non regged PCP does)
- transfer port restricted to dial out the peak flows in the midrange - something around 2mm, but from my experience of careers, you need a tighter port, prob around 1mm
- valve flow reducers - careers have these around the stem inside the valve- make sure yours is still there
- stronger valve return spring (screws into the fron the the vale, accessible from muzzle end) closer the valve qicker at low pressures
- lighter hammer, reduces dwell
check #1 and #2 first, #3 is fairly strainghtforwards but needs a full strip (actually, #2 may do too - depends on alignment of the port and valve).
#4 is simple, but you need a lathe - and I don;t know if your version has a stepped front face...
HTH - JB
Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.
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