GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Show us your Custom Airgun Parts (TRICKS-N-TIPS) => Topic started by: ZipSnipe on August 05, 2012, 12:01:31 PM
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Ok as some of you know ever since I have done the bullpup mod I have had issues with the new 1077 I bought as well with the older 1077 leaking c02. I have determined three areas that this happens.
The first 2 areas are the connection points at the transfer tube. These are just the tube pressed into rubber grommet style seals.
The third area is the valve puck assembly which is basically a brass washer with a molded plastic puck pressed into it and the hammer pin goes inside of this. I have found these pucks to be as much as .010 gap around the hammer pin allowing c02 to escape when fired.
So my fix for the transfer tube is pictured and basically all I am doing is adding a clamp to the tube with fittings on it to create a better seal. The fitting (MSC and Mcmaster carr carry it) going to the c02 piercing valve will be threaded to that part of the valve. The other end of the transfer tube fitting will be custom made on my lathe so that the tube press fits into the fitting and for extra measure silver soldered. Then the clamp slides over it to clamp it securely to the valve.
The rear of the valve we will replace the brass and delrin puck with a one piece brass assembly drilled out so it's a half a thousands gap around the pin. There will also still be some type of plastic seal as the pin needs to be air tight when not fired, I will experiment with different types. I just researched delrin and found that it is not a good seal for c02. This is on the newer style valves the older style valves seem to be correctly made in my opinion.
Hopefully we will see an improvement in power,
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I also wanted to point out that the transfer tube part of the mod will actually create two layers of seal. The piercer end will still have the regular seal plus the compression fitting part and the valve end will use a regular seal and a slightly larger seal and then the clamp will press against both of those.
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So got to shooting the Bullpup and it blew a seal(brand new seal), so mod is in order!!
Also this is not going to be a cheap mod, I have to order a special tap at $24, the fittings is $4, I was going to order 3 fitting( one for each gun) so probably around $45 shipped. The rest of the mod I can fabricate in my shop.