Adding a bit longer air cylinder to PP750

[Motorhead]

So there is no way to use that cylinder? Bummer. I am getting around 25 good shots with 10.34 pellets shooting at around 880fps and that is with the gauge block and 16 inch FX superior liner. I was getting around 900 for the first couple of shots, but later I figured it was due to creeping regulator.
I now ordered Huma regulator, so I'm hoping to improve efficiency a bit at 900fps. I have unristricted model, but haven't done any porting.
Any advice would be appriciated.

I know about OPENING up a PP700 series to get it breathing better, placing OEM Reg into bypass / gutting it & using a HuMa "In-Tube".
Never been into the PP750, so lack knowing if or where it differs ?

 

[thane]

PP750 is lever/probe breech with magazine, in tube real adjustable regulator with a coil spring in conventional cylindrical hammer, barrel in threaded thimble, transfer port in thimble, very small plenum volume.

Unlike the single loading PP700 swing block breech, transfer port in block, regulator lite, thumb lever hammer, better trigger.

 

[Vlada1911]

How much power do you think it's obtainable with PP750 in .177 with 16 inch barrel, Huma regulator and larger plenum while keeping some 25-30 shots autonomy?

 

[thane]

Currently working up a 14.5" and 15" barrels with 12FPE goal. Going over 12FPE is not difficult even with 8.5" barrel. It is getting to 30 shots.

The 14.5 makes 24 shots... then spikes as it comes off reg. 15 cu in bottle with ninja reg @ 1,350 PSI makes probably 100 good shots, but bottled pistols are more like carbines, especially with a 15" barrel.

I will turn up my reg, slug the hammer with 5 more grams and find out... hope the poppet holds.

 

[Vlada1911]

Looks like I'm close to max, then. It's shooting around 17FPE and makes 20 good shots with 125bars on a reg. I'm thinking about turning a reg to 130-135 once huma arrives and cutting one coil from a hammer spring to see what happens.