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    In the past there have been two common methods of attaching the magazine tubes to the interrupter blocks (the part with the ball bearing or piston). The first is to use compression fittings. The second is to solder the tube into the fitting. Soldering the tube gives you a gas tight seal but creates two problems. You can not see the piston to adjust it when you assemble the gun (or have to take it apart), and it makes for an awkward (sometimes impossible) job of installing or removing the gun. While the compression fitting assembly allows for the previous problems it has some of its own. The main problem is that to get a gas tight seal with just the fittings you have to tighten the fitting to the point that it crushes the copper tubing past the point where a BB can go through. You could solder the compression ring to the tube and use Teflon tape to seal the joint. This generally does not do a good job. Also you still need to tighten the assembly with a wrench. This is generally not too much fun either, with the limited room available.

    I have come up with a fitting method that solves the problems associated with the regular compression fitting joint. The joint is gas tight and can be tightened finger tight. The joint uses an o-ring and a modified compression ring. A cross-section of the joint is shown below (Figure #1). The compression ring has the sloped portion of one side cut off. This ring is then soldered to the copper tubing with the newly created flat toward the end of the magazine. An o-ring is pushed over the tube and the joint assembled. The compression ring should be positioned so the there is about 1/2 of an o-ring width between it and the interrupter block when the magazine is in position and no o-ring is installed (Figure #2). The o-ring used is just smaller in inside diameter than the 1/4 inch tube outside diameter and .065" (or a little over 1/16") thick. To cut the compression ring, slip it over a scrap piece of 1/4 in. tubing (Figure #3). Then cut two pieces of brass tubing (one ea.) the next two sizes larger than the copper. Slip these up to the ring and tack solder the outer one to the ring. Be careful not to solder the ring to the copper tubing. Clamp the assembly in a vise (clamp the end with the brass tubing). Cut the ring on the sloped side of the ring that is soldered to the brass. This should leave you with a modified ring with a sloped side and the center flat part. Remove the ring from the stub of the copper and sand the cut edges smooth.

    This process is not as tricky as it seems, I managed to make three good rings out of four tries. Slip a compression nut onto your magazine followed by the modified ring (flat side toward the fitting end). Put the end of the magazine into the interrupter block. Position the ring so that there is about half an o-ring thickness gap between the flat side and the end of the block. Mark this and solder the ring on (solder from the nut side). You now have a gas tight Mark 1 fitting. If you are careful you can unsolder the brass tubes from the scrap piece and reuse them a few times.

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