Swoosh-Air Bolt Insert Mod

I have been pondering this modification for quite some time but never got around to it till recently. Thought about how I could enhance the flow a bit more in the stock Spyder bolt and rid it of that 90* turn the pressure takes as it enters the bolt from the air passage through the valve. Rather than taking that abrupt 90* turn, how could it shoosh its way right through? Initial thoughts were to use some sort of epoxy or similar and drop it in the corner left to harden which would create an angle for the flow. In doing this you cannot easily control the shape and angle of the curve though and you may be left with something that would direct the pressure on a bogus angle which may have a negative affect on the paintball leaving the barrel. Then it dawned on me, why not just use a piece of round light material, modify it into a specific shape and simply bond it into the bolt? Now you have control of the specific shape and angle that the pressure will hit the paintball. Why didn't I think of that before?

Materials

Don't let me influence you into using any specific material. You may know of a better material and if so, use it. The material used to make the insert should be relatively light so not to add too much weight to the bolt. Depending on your tool availability, it needs to be something easily modified or shaped. It also needs to be a material that can withstand possible paint breaks in the marker and also impervious to the oils or greases used to lube your marker. For my initial insert I am using a 1/2" wooden dowel rod and a methyl ethyl ketone peroxide(MEKP) with unsaturated polyester resin mixture to coat the insert with. The liquid fiberglass once hardened, should protect the wood from absorbing any foreign substances that could possibly soak into it and work as a bonding agent as well. It will also make a nice smooth surface for the pressure to glide across. Liquid polyurethane was another nominee that has a similar effect on wood as fiberglass but I have a limitless access to the fiberglass so fiberglass it was. In the future I plan to use some sort of 1/2" plastic material and a slow drying epoxy to bond it to the bolt. Steel is completely out of the question because it would add too much weight to the bolt and I think aluminum would as well.

Making The Insert

When purchasing the dowel rod, you'll notice that all aren't created to the same exact diameter. I would suggest taking the bolt with you and trying them one at a time until you find one with a snug fit.

Mark a line around the dowel rod about 1/2" - 5/8" from the end. If you have access to a ban saw you may start by cutting a swoosh arc from the top/center of the line you just marked to the bottom center of the front surface of the dowel rod then use the barrel sanding attachment to smooth out the cut afterwards. If you don't have access to a ban saw, you can just use the barrel sanding attachment and dremel and make the swoosh arc. Try to make the arc ends as close to the 2 edges as possible. Make the arc as flat across the dowel rod as possible. What you're left with should look like the photograph above but the insert is still attached to the dowel rod. There may be some small ragged spurs of wood left on the edges. Use some very fine grit sandpaper and lightly sand the spurs off.

You'll need to make a perfect 90* cut on the line you marked around the dowel rod earlier. A ban saw would make this an easy task. If you don't have one, using a miter box and saw used for cutting wood trim is another option. If you have neither, just try to make the cut as 90* as possible with whatever saw you have available. Make the cut just past the line and not right on or before it. You can always remove material but adding it you cannot. Now your swoosh insert should look exactly like the one in the photograph above. Lay a piece of 100 grit sandpaper on a flat surface such as a table. Using the line you marked earlier as a guide, scrape the 90* cut edge across it in a circular motion and remove any excess wood flush to the line. It is important to keep this surface as close to 90* as possible as it will be flush with the back most portion of the bolt where the venturi was once screwed into. If you make it on a bad angle there will possibly be a gap between the insert and back wall of the bolt. This would disturb the flow of pressure you are trying to enhance in the first place with the insert. While sanding, you can sporadically install the insert to check for square fit.

Installing The Insert To The Bolt

Now that you have the insert completed and checked it for fit, it's time to attach it into the bolt. Of course you'll need to remove the venturi prior to installing this insert. Look in the 'LP free mods' article for that information if needed. Use a solvent to remove any oil, grease or paint residue from the area inside the bolt where the insert will be attached. Our target here is to have the front most portion of the insert as close to 90* as possible from the centerline of the bottom pressure through hole in the bolt. We also want the back portion of the insert as 90* flush as possible with the back wall of the main channel that goes to the front of the bolt.

You'll want to have a few things handy when performing the attachment: a solvent like acetone or paint thinner, q-tips, an old cotton rag and a small sable type paint brush. You will need the solvent, rag and q-tips to clean up any excess epoxy, polyurethane or liquid fiberglass from the bolt. You'll need the paintbrush to apply the liquid attaching medium. You'll also want some sort of utinsel such as a small screwdriver or the like to manipulate the insert in and out of position. What ever you use, try not to gouge it into the insert when using it.

With the insert in place as described above, move it slightly forward to the front of the pressure hole. Brush on the liquid fiberglass resin(or whatever) where the insert will be and brush some on the back of the insert as well. Slowly push the insert back into place making sure it's exactly in the position that you want it and remove any excess that leaks from between with a solvent soaked q-tip and/or rag. Now brush a coating across the top surface of the insert and clean any excess from the sides and you're done. Make sure you leave no excess resin on the outside of the bolt.

I would suggest letting the bolt dry leaving it on a backward angle, hole up so there's no chance of any excess from between the bolt wall and insert leaking forward into the main pressure channel. I let mine dry for 24 hours before even touching it again to make sure it was completely cured. If you'd like, you can brush on another coat or two to the top surface of the insert.

Cutaway showing insert shape, position and new swoosh-air flow properties

Testing

After performing a 10 shot velocity test between a stock bolt with the venturi removed and the exact same type of bolt with the insert installed, the overall averaged increase was 8.1fps with the swoosh-air insert bolt. Not a monumental increase but an increase just the same. There was an added bonus that I did not think of though. Not only was the velocity increased but the consistancy of the velocities were increased by 50% as well. Of the 10 shots with the regular bolt, 8 of the shots were within a 6fps range of each other. 8 of the 10 shots from the bolt with the insert installed were within a 3fps range of each other. A nice surprise to gain more than I had expected from this small added insert.

This test was performed with a '05 Imagine with Rocket valve, Palmer's Stabilizer, light striker spring, HP compressed air tank, opened and polished internals, custom modded striker, J&J ceramic barrel and RPS Evil paint. The pressure was set at 300psi. If you do not have the same exact setup, you may experience an increased or decreased result.

Technical Information