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Moving O-ring Muzzle For Large Slider Shafts (Inspired By The Seatec Evo-Air)

OP
OP
Diving Gecko

Diving Gecko

shooter & shooter
Jun 24, 2008
1,408
332
138
Shanghai
You could always check automotive engine parts lists for engine valve stems that have 8.5 to 9 mm shanks. The oil seals have the job of stopping oil being sucked into the combustion chamber during the piston's downstroke on the fuel/air intake with the valves open and preventing the engine burning oil which would eventually carbon up the valve heads and seats. Truck engines as well as cars, or even boat engines, they all have oil seals on their valve stems.
I have indeed checked those, but from my initial searches it looked like they tend to max out at 8mm. I only found one in 8.5mm but it was in the UK and not cheap. I might check again.
Dima said they used to use them in the old days before he made his own seals.
 

popgun pete

Well-Known Member
Jul 30, 2008
3,372
743
153
Australia
I have indeed checked those, but from my initial searches it looked like they tend to max out at 8mm. I only found one in 8.5mm but it was in the UK and not cheap. I might check again.
Dima said they used to use them in the old days before he made his own seals.
It is the same in Russia, parts from various vehicle engines such as the Zil. The RPS-3 shoots a 9 mm shaft, but its rubber seals are worthless rubbish. I have over 40 of them, sourced from two guns.
 
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tromic

Well-Known Member
Aug 13, 2007
1,615
180
153
Croatia
DIY Vacuum Cuff (Yes, A Thread Drift...)
I am allowing myself a derail of my own thread as, at this stage, the following does not yet deserve its own thread.
But here's a quick sketch of how a muzzle with a home cast PU cuff could look (as mentioned, I could 3D print molds for cuffs):
View attachment 55044

The inspiration comes from the STC cuffs and oil seals and the muzzle design could be simplified a bit more. Perhaps with the retainer lip being only on the inside of the seal:
View attachment 55046

So far, the seal itself is optimized for 8-9mm shafts. And if I went forward with this, I would work on trying to make the "moving" part of the seal as small as possible to reduce how much rubber can be compressed onto the shaft.
The design in this sketch weighs about 44g and is 58mm long. That's a few grams lighter than the Vuoto and a full cm shorter.
Italian Duccio Lengas made his own sealing cuffs..

Here is a video about how he use it for STC kit modification..
 
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