My shinsung 201 9mm developed a very small leak out the pressure gauge so I decided to disassemble the gun and replace any orings that were defective. So out of curiosity I'de disassemble the whole gun and made a post about it.
I am not claiming this to be a tunning job! I am not a airsmith or claim to be one ! This is an information post for anyone who may be wanting to tackle the disassembly of theShinsung 9mm. Some day I may make a youtube video of the disassembly. It would be the only one in existance I'm sure. And yes it is holding air perfectly ! I havn't got out to shoot her yet but I know there will be a diffrence!
Enjoy!
I did some minor polishing and seal replacement as you will see.
Let’s start at the muzzle end and remove the gauge . Remove dust cap and sight cover.
Remove the fill port
Fill port removed
Remove the two locking rings. I didn't have a small spanner wrench so I made this tool.
Tap the end cap off with a wooden dowel
Unscrew the monometer gauge. I pinched a leather strap with vise grips to turn the gauge
Pressure gauge out
Unscrew the aluminum cap on the end of the gauge
To get to get at the stem seal insert a flat blade screw driver into the guage and hold the other end with another flat blade
The threaded cap comes off the end of the stem.
Go inside and remove the brass nut that houses the oring. This is what was leaking
Oring in nut. The leaking Culprit!
I had to ream out a new oring so it would fit the stem. The ring on the left is the reamed out one. The oring on the right is what the brand new oring looked like. Too small in the inside diameter especially after getting tightened too. It had to be modifide
This is the toolsI used to ream the oring
Fits perfect. I lubed the oring and reassembled the gauge.
Next I lossend the fill inlet tube with a small drift through the port hole.
Remove forestock one screw.
Remove screw that holds trigger in place
Trigger out
Remove two scope rail screws. Note the longer screw toward the rear of gun
Separate action tube from cover
The transfer port dowl will stay in one of the two pieces. Take it out. Inspect and or replace both orings on port
Pull off breech cover and inspect barrel oring
Unscrew barrel and remove. Plastic barrel spacer comes out with barrel too.
You will need an 18 inch flat wide blade screw driver or a flat blade that fits in a socket for the next procedure. I made this flat blade and cemented it into a ¼ inch socket.
Reach up into the air cylinder with the flat blade and unscrew the end cap 3-4 turns. This loosens the expanded oring from the inside of the cylinder.
Remove the three screws and the scope rail nut so the valve can be pushed out the breech end.
I used a broom pole to go up inside the air cylinder from the muzzle end and push the valve out he breech end.
Unscrew with your hands the valve, You can see the delrin valve and spring
Remove the delrin valve and with a flat blade screw driver remove the valve stem oring cap.
Inspect oring
The original valve (wrapped in brass) was replaced a few years back. The new valve stem had been ground down for a power tune at the time. I believe it was to allow more air flow out the exhaust valve.
Here you can see the valve stem inside the exhaust valve body and how the smaller stem most likely has an affect on air flow out of the valve.
I polished the cylinder only the first 4-5 inches where the hammer slides. I started with super fine steel wool with a mild compound
I finished the polish with cotton cloth and blew out and degreased cylinder.
Buffed up the hammer
Nice and smooth
Reinstall the exhaust valve assembly and install three screws and the scope rail mount nut
A very light coating of Honda moly is is applies to the inside of cylinder up to valve for the polished hammer to slide freeer
Install thrust washer and hammer spring. Make sure tit of washer is facing forward so it will engage with detents on cocking bolt
You can insert cocking bolt which helps to hold the hammer from turing when you are compressing the spring and putting in the pin, Then pull the bolt back out again.
Screw barrel back into place . This is a good time to put some rust preventer on the part of the barrel that is hid under the rear sight
I used the leather and vise grip to tighten the barrel back up
Slide the plastic barrel spacer between the barrel and air cylinder
Reinstall the air inlet tube and snug it up
Reinstall the pressure guage and snug it up. I used the leather strap again.
Set the front cover in place and tap it home with a wooden dowel
Make sure your gauge is straight before you install the end caps. If the gauge needs to go clock wise more you can use the slot in the aluminum end cap to turn it but if it needs to go clockwise you may have to tap the end cap off again and turn ut back with the strap. If you used the slot in the end to turn it back the cap will probally just unscrew
If your gauge is straight the install the two end collars
Reinstall the barrel seal and the brass breech cover
Inspect the transfer port dowl and replace orings if necessary. Lube and install the transfer port into the cover or on the cylinder exaust tube. I chose to install it into the cover. I also polished the ports to a bright smooth finish.
Almost a mirror finish. Both ends
Bring the two pieces together
Install the scope rail with two screw
Install trigger assembly and tighten screw
Install forestock
Done, Clean off grease and prints.
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