Seven examples are shown in the above photo of types of foreshafts or heads I have used in prototype subcaliber blowgun darts. The particular subcaliber darts made with these foreshafts/heads were stabilized by a lightweight, hollow shaft extending rearwardly from the foreshaft/head. I will show the shafts and assembled darts, and sabots used to launch them from a blowgun, in other posts. For now, let's take a closer look at each of the dart heads/foreshafts in the above picture.
Starting from top left, and working my way down the diagonal towards bottom right:
1. I modified a Muzzy brand broadhead assembly for a bowhunting arrow to make this blowgun dart component. The modification was simply to leave out the broadhead blades. This particular broadhead, if fully assembled with the broadhead blades, would have a 75 grain mass. With the blades left out, it's quite a bit more light-weight. To make a dart with the modified Muzzy assembly, I shim the threaded screw-in portion at the rear and then slide a section of plastic soda straw, about quarter-inch diameter on. The slight swell in the broadhead assembly right before the rear threaded rod is a bit wider than the cutting diameter of the three cutting edges of the trocar tip. When shot through a tin can, the trocar tip plus the slightly wider rearward portion opened some big holes!
2. This is simply a replacement trocar tip that can be screwed on to the front of a Muzzy broadhead assembly such as shown in (1). This trocar tip, though, is for the 90 to 100 grain Muzzy broadhead assemblies. It has a hollow portion in the back, which is threaded to allow it to screw on to the front of the broadhead assembly. A somewhat narrow soda straw can be inserted into the hollow portion to make a quick-and-easy, lightweight subcaliber trocar dart. Or, to make a more heavy weight dart, a shaft such as a wooden dowel rod, fiber glass rod, or rod of metal can be inserted into the hollow and glued or otherwise fixed in place. With a full caliber fixed-cone dart with a 12 inch wooden shaft, this tip just barely stopped short of passing completely through both sides of a tin can, so further testing with heavier darts is indicated. Fun!
3. This is an example of a screw-in field point for an archery arrow. I believe this is a 75 grain point. A lot of variety of sizes shapes and weights of this general type of field point are available. A straw stabilizer can easily be attached by sliding onto the threaded portion at the rear, with some tape or shrink tubing for shimming if needed. Quite a bit heavier than the modified Muzzy assembly at top, it take a little getting used to, but can be very stable and accurate, not to mention hard hitting, once you've gotten accustomed to it.
4. An example of a different weight/size/shape of the general type of arrow field point shown in (3). This one has more of a bullet-shaped point.
5. A very simple to make foreshaft made from a finishing nail. I often use such foreshafts/heads with the blunt nailhead facing forward in the finished dart. Here, instead of the approximately quarter-inch diameter plastic straws that I use in the darts with the repurposed arrowheads shown above, I use the kind of narrow, approximately one-eighth or one-tenth inch diameter sipper-stirrer plastic straws that are used for coffee drinks. The blunt head performs something like a wadcutter pellet used in airguns, and punches nice holes in a shoot-through target face. Darts made with the narrow sipper-straw shafts are an interesting example of a type of shaft-stabilized low-drag blowgun darts. Even the darts made with wider soda straws have lower drag than might be apparent at first glance, since they are still narrower than the wide stabilizer cones typically used on full caliber blowgun darts.
6 and 7. These two dart heads/foreshafts, like (5), has been designed to accept a narrow sipper-stirrer straw shaft as a stabilizer. These heads/foreshafts have been made by supergluing a small steel brad through the hole in a small tungsten "worm weight" which is repurposed fishing tackle. The tungsten head is heavy and compact, so the weight of the finished dart, with the lightweight straw stabilizer attached, is concentrated very much towards the front of the dart. It's almost like a streamlined pellet with an aerodynamic stabilizer/rudder attached to it on a (relatively) almost weightless lever arm. Custom-made tungsten foreshafts/heads for blowgun darts could be tailor made to the shape, size and weight required for various types of shooting, including target, hunting and flight shooting. Even in fishing worm weights, there's a wide variety of weights/masses available, even lightweight 1/32 and 1/64 oz sizes. So far, I've used 1/8 and 1/16 and have been very pleased with the results. You do have to get used to judging how heavy the dart is, so that you know how strong a breath to use when shooting it... the tungsten heads are very compact for their mass. A variation that I have worked with, and plan to develop more for flight shooting, is an ultra-low drag blowgun dart based on a heavy, compact head like these tungsten heads. In a prototype of an ultra-low drag dart, I took a small tungsten worm weight and glued a section of thin, stiff, light-weight music wire into the narrow hole through the worm weight. When in use (being launched from blowgun), the tungsten head is at the front of the dart, with the music wire shaft protruding backwards to serve as a stabilizer. Although in my tests so far this music wire-stabilized dart did not shoot nearly as accurately as the darts made with plastic straw shafts, the music wire was a sufficiently good stabilizer to keep the dart flying head-first. That degree of stabilization would likely be sufficient for long distance flight-shooting, in which accuracy is not important, but rather how far the dart travels before falling to earth. Meanwhile, the slender music wire should be well adapted to shed drag in flight. By the way, for the dart heads/foreshafts shown in (1) through (7), the straw stabilizers used with them are usually a bit narrower than the widest portion of the head. This helps protect the straw shaft on impact with a target, and makes it easy to seat the shaft securely. The transition from the wider portion of the head/foreshaft down to the somewhat narrower shaft stabilizer may also in certain darts create some drag which contributes to the overall aerodynamic stabilization of the dart.
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