Adding a bit longer air cylinder to PP750

[Vlada1911]

Hello, everyone.

I've been reading forums looking for solution to this problem that probably doesn't even exist, and coudn't find anything.

So, I have modded .177 PP750 with 16 inch FX superior liner and quite a few more mods. It is now shooting JBS heavy's around 920 FPS with regulator sat around 125-130Bars.

What I would like to do is replace the air cylinder for the one with the same diameter, so I would keep original lines, but around 5 inches longer to gain few more shots.

I found one cylinder on Aliexpress with good diameter, but it is a bit longer than needed.

Does anyone know is it possible to cut the cylinder to desired length, rethread it and keep it safe?

Please check the pictures of the cylinder I found.

I'm not sure if the connections are compatible, too.

 

[thane]

A product link would be helpful.

 

[Vlada1911]

Sure. I tried sharing Aliexpress links before, but they led to no where.

https://m.fr.aliexpress.com/item/1005005171951058.html?srcSns=com.brave.browser&spreadType=socialShare&bizType=ProductDetail&social_params=21033669526&aff_fcid=cc9f0d31783f4b1ba3acb2783512e216-1688060683476-05236-_m04RWZO&tt=MG&aff_fsk=_m04RWZO&aff_platform=default&sk=_m04RWZO&aff_trace_key=cc9f0d31783f4b1ba3acb2783512e216-1688060683476-05236-_m04RWZO&shareId=21033669526&businessType=ProductDetail&platform=AE&terminal_id=05b50b9203734703acd507a35c98a4a9&afSmartRedirect=y

 

[Vlada1911]

Some drawings from that page (if you can't open it)

 

[thane]

Found on alibaba, ordered a sample... I will let you know how it goes.

 

[Vlada1911]

Oh, man, aren't you quick on the trigger!
You are going to work on it?
12-15 more shots out of if would be great. What long is the barrel of your PP750?

 

[thane]

Stock barrel is 8.5", I have one converted to 11.5" in .22.
Setting up one in .177 @ 15" for Pistol Field Target gun so it needs to stay under 12FPE and get 40+ shots.

 

[Vlada1911]

Oh, wait, I've seen your work! Love the grips you made.
Excited to see what will come out with that cylinder.
Here is mine. Measured how much space I have to moderator- 12cm exactly. Maybe I can manage half an inch more if I get huma quick connector for moderator.

 

[thane]

Carbon is looking awesome, Carm single loader is super good, nice rig.
PP750 are a great building platform.

 

[Deadlands]

I have a PP750 and an Artemis P15. The air tubes are the same diameter and i think same thread size at the block. The P15 tube is much longer and may be exactly what you need…if you can get ahold of a spare.

 

[keesbo]

M28X1 is the tread size in the tube.

 

[Vlada1911]

Unfortanetly, I haven't been able to find P15 tube in my country.
Looking to add Huma regulator first, as factory one shows 20bar higher pressure for the first 2-3 shots, and Huma migh even give more space for the plenum than the factory one.
Untill then, Thane might recieve his cylinder so we'll se what is possibe.

 

[thane]

Won't know actual dimensions until it arrives, section and description are conflicted with 3 different dimensions called out.
Unfortunately this is common on Alibaba. May need to turn an adapter.

Dimensions should be the simplest information to communicate...

 

[Safet22]

I have a modded pp750 as well! Once I get home from work I’ll share some pics. Do you mind sharing your set up?

 

[Safet22]

Oh, wait, I've seen your work! Love the grips you made.
Excited to see what will come out with that cylinder.
Here is mine. Measured how much space I have to moderator- 12cm exactly. Maybe I can manage half an inch more if I get huma quick connector for moderator.

View attachment 368655

Where did you get the pic rail?

 

[Vlada1911]

Where did you get the pic rail?

I bought it localy. Its a chinese one, and not a good one. Can't be leveled so I'm looking for a better one.

All the other parts I added:
- FX superior liner 16 1/2"
- Carbon fiber shroud
- BobP's 3D printed adjustable cheek rest. He only does shipping to UK so if you are not local, better find somebody over there willing to purchase it for you and send it, like I did.
- Huma Mod 40 avalanche moderator that I protected with some thick heat shrink
- Gauge block from Wes
- CARM SSL and magazines
- Atlas clone bipod mounted on a 3d printed clamp
- Hawke 4-12x40AO scope

Looking forward to pics of yours.

 

[Vlada1911]

Won't know actual dimensions until it arrives, section and description are conflicted with 3 different dimensions called out.
Unfortunately this is common on Alibaba. May need to turn an adapter.

Dimensions should be the simplest information to communicate...

And it looks like they are selling a lot of them. Not sure how, when their description is so unclear.

 

[rdpjr6504]

A little late to this discussion but why not bottle it ? A lot of shots weighs 6 lbs scoped with the help from FIREWALKER doing the machine work on the block.

 

[thane]

Sample tube arrived at 500mm long, nothing about it measures 400 mm. Diameter is a couple mm too large.
May turn a offcenter adapter to offset tube... doesn't fix the extra 100mm.

This PP750 is going into FT Pistol duty which restricts overall length to 25", front grip depth to 3" under bore CL and entire barrel assembly to 15". Currently wood grips, LW Slow Poly 14.5" barrel with CF fitted tight on barrel and into reduces original shroud. Makes 40 shot 3/8"group at 25 yards, much improved from 8.5" barrel. Refill at shot 24 to stay under 12FPE limit, velocity increase coming off reg is severe due to small plenum volume.

The bottle drop is going to be next for a second build, pick up some plenum volume as well, see how it handles... building is almost as fun as shooting.

 

[Vlada1911]

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.