Enter the Trocar

Exploded and assembled views of subcaliber blowgun dart provided with a highly efficient trocar penetrating tip and a streamlined shaft/stabilizer made from a plastic soda straw.
Exploded and assembled views of subcaliber blowgun dart provided with a highly efficient trocar penetrating tip and a streamlined shaft/stabilizer made from a plastic soda straw.

A trocar tip may give your blowgun dart just the edge(s) it needs...

Subcaliber blowgun dart of the type above, with trocar tip and straw stabilizer, shown seated against a lightweight conical shell sabot.
Subcaliber blowgun dart of the type above, with trocar tip and straw stabilizer, shown seated against a lightweight conical shell sabot.
Another example of the same type of blowgun dart, showed seated against a sabot provided with a forward-facing projectile engagement socket.
Another example of the same type of blowgun dart, showed seated against a sabot provided with a forward-facing projectile engagement socket.
Two types of darts were tested on this steel can.  One, a conventional "spearhead" type dart with a flattened point, which made 2 small holes.  The other, one of my prototype trocar darts, which made three much larger holes.
Two types of darts were tested on this steel can. One, a conventional "spearhead" type dart with a flattened point, which made 2 small holes. The other, one of my prototype trocar darts, which made three much larger holes.

Shoot Safely!

Please be sure to always follow the first rule of all shooting sports, which is to shoot safely and responsibly.  I've included some tips on safety when shooting Blowguns, which appear in boxes along the side of this Hub article.  Shooting sports are fun, and can in fact be among the safest kinds of sports-- when practiced safely and responsibly.  The information and tips presented in this Hub article are done so with your safety in mind, however I cannot guarantee your safety if you make and shoot blowgun darts or other types of projectiles.  You must always exercise caution, awareness, and personal responsibility when engaged in shooting and hunting activities.

Another one of my prototype trocar darts.  This one has a full caliber fixed-cone stabilizer, a 12 inch wooden shaft, and a trocar tip.
Another one of my prototype trocar darts. This one has a full caliber fixed-cone stabilizer, a 12 inch wooden shaft, and a trocar tip.
Close-up of the trocar tip of the wooden-shafted full caliber dart.
Close-up of the trocar tip of the wooden-shafted full caliber dart.
Another close-up of the trocar tip, showing how the meeting of the hollow-ground sides or facets creates a sharp cutting edge radiating from the point of the trocar.
Another close-up of the trocar tip, showing how the meeting of the hollow-ground sides or facets creates a sharp cutting edge radiating from the point of the trocar.
Closeup of the dart's stabilizer cone.  Note how the tape has "accordianed" after multiple shots into a plywood target.  Meanwhile, the trocar tip (above 2 photos) shows no damage.
Closeup of the dart's stabilizer cone. Note how the tape has "accordianed" after multiple shots into a plywood target. Meanwhile, the trocar tip (above 2 photos) shows no damage.

Recently, on the Lefora Blowgun Forum (where, instead of being known as "Watcher by Night", I go by the equally eccentric moniker "Curare-Five-Oh") I posted some ideas I had about making blowgun darts with trocar tips, along with some pictures of subcaliber darts I’d already made with trocar points and the results of shooting one of the darts into a tin can.  It made some nice big holes in the can, which you can view above, and in more detail at the link that appears at right.  

The pictures above with captions show views of the subcaliber trocar dart, the sabots used to launch it, and the grisly details of its "terminal performance" on a tin can that was targeted for testing.

The pictures to the side show a more conventional type of full caliber blowgun dart which has a fixed-cone stabilizer, and which I’ve also fitted at the forward end with a trocar tip.  I’ve already shot the  wooden shafted dart quite a number of times into tin cans, wood, and plywood.  (see my note on safety below).  If you look at the close-up of the stabilizer cone, you can see that the tape fixing the cone on the shaft has crinkled up like an accordian.  It wasn’t originally that way, but multiple impacts with the plywood have successively pushed the cone a tiny bit forward to where it is now, crinkling the tape in the process.  

Results with this wooden-shafted trocar dart have been encouraging.  The dart stopped just barely short of complete pass-through on both sides of a steel soup can, and made deep pyramid-shaped holes in quarter-inch plywood, with the very point of the pyramid almost reaching the far side of the plywood--- I could see a hairline crack formed on the far side of the plywood each time.  

I’m not done with the testing yet.

Next step I’ll take is to put a trocar tip on a heavier dart.  The dart pictured above uses a 12 inch section of 3/16 inch wooden dowel rod as a shaft, which is not very heavy.  I could use a longer dowel rod section, but happen to have some solid brass rod on hand that is about 3/16 inch diameter, so I’m just going to make a short but heavy dart with the brass rod.  Eventually I hope to locate some fiberglass rod of the proper diameter and hopefully in a bright orange that would contrast well with the black trocar tips.  

In the meantime, I believe the heavier trocar dart will punch a quarter-inch hole completely through quarter-inch plywood, and I bought a 2x2 foot square of pristine quarter-inch plywood last night to have on hand when the dart is ready.  (and a 2x2 foot square of three-eights inch plywoood, for the next step in trocar penetration tests, assuming all goes as expected with the quarter-inch plywood).

(continued below)



Full length view of wooden-shafted full caliber trocar dart.
Full length view of wooden-shafted full caliber trocar dart.
These two partial exit holes are like freeze-frames showing how the trocar cuts and penetrates.  The small, triangular hole on left shows early stages of penetration.  The larger hole on right shows almost fully opened flaps after almost complete exi
These two partial exit holes are like freeze-frames showing how the trocar cuts and penetrates. The small, triangular hole on left shows early stages of penetration. The larger hole on right shows almost fully opened flaps after almost complete exi
For my prototype trocar blowgun darts I used components from a Muzzy brand archery arrow broadhead.
For my prototype trocar blowgun darts I used components from a Muzzy brand archery arrow broadhead.
A view of the pyramidal facets of the Muzzy brand trocar tip.
A view of the pyramidal facets of the Muzzy brand trocar tip.

Blowgun Shooting Safety Tip

A theme emphasized at the "Box O' Truth" ammo penetration testing website linked above, is to follow safety rules at all times and to be responsible for every projectile you send "downrange".  With a blowgun you must also use common sense and follow proper safety procedures.  Remember that when doing any kind of ammo penetration testing, there's always a possibility that a projectile or piece of the target may bounce back at you.  When I tested the wooden-shafted trocar dart (shown above) on plywood, sometimes the trocar tip would stick in the plywood.  Other times, although the trocar tip almost penetrated through the plywood, the dart would bounce out, usually just dropping to the floor beneath.  However, a few times the dart rebounded several feet, and one time the dart rebounded over ten feet.  I was standing over 10 yards from the target, so the rebounding dart came nowhere close to me.  Even so, I wore shooting glasses at all times.  For any type of shooting, and especially for penetration testing, you must be familiar with the characteristics of the projectile and the projectile launcher.  And you must always be prepared to expect the unexpected.

So why bother with trocar tips on blowgun darts?  And, if you haven’t heard of them before, what exactly is a trocar? Of course you can google “trocar” or refer to Wikipedia, but I’ll try to describe it briefly here.  Trocars are very efficient penetrators, and often take the form of a tool or instrument with a peculiar sort of sharply pointed tip which transitions into a number of cutting edges, often formed by the meeting of faceted sides of the trocar.  The number of sides and cutting edges may vary on alternate forms of trocars.  Among other things, trocars are used in surgery, for things like installing drainage shunts in a patient’s torso.  In “times of old”, trocars were used as points on knight’s lances--apparently they helped punch cleanly through opponents’ plate armor when jousting took a lethal turn.  If you’re a bowhunter, you may be familiar with chisel points for arrow broadhead assemblies.  Chisel points are compact and rugged, and are often intended to increase an arrow’s ability to split bone when penetrating a deer or other animal.  Muzzy is one manufacturer of arrowhead assemblies that employ a type of trocar chisel point, which I’ll describe in more detail below.  


Let’s take a little more detailed look at the particular trocar dart that I pictured above, and how the  trocar tip works when shooting a target like a tin can.  This particular dart is tipped with a trocar point manufactured by Muzzy.  The point looks kind of like a three-sided pyramid, with three edges defined by the meeting of the three sides of the pyramid.  The edges come together in a single sharp point at the pyramid’s very tip-top.  This particular trocar tip appears to have been hollow-ground.  This means that each of the three sides of the pyramid has a slightly hollow or concave look, so that each side is “plano-concave”.  The hollow-ground sides of the trocar tip causes the cross-sectional angles formed by the sides meeting at the edges to be smaller; consequently, the edges are sharper than they would be if the sides were simply flat facets.  What happens when this trocar tip impacts a target, is that the sharp tip of the “pyramid” pierces first, and cutting contact radiates from the point along the “Y” defined by the three sharp edges, very quickly cutting a “Y”-shaped slit in the target.  This three-pronged slit creates three flaps in the material.  As the tip penetrates more deeply and the side facets of the pyramid contact the target, the three flaps are pushed/shunted aside relatively easily, creating an opening which the shaft of the dart, being a little bit narrower than the trocar tip, can pass through with relatively little frictional contact.   Of course, a trocar or chisel point could have other than three cutting edges and side facets, but this gives a general idea of how trocars cut and penetrate on contact.  

Now, granted, you don’t always want a blowgun dart to penetrate a target very efficiently.  For certain types of target shooting, especially for competitive sport blowgun shooting, overpenetration can damage the dart, shorten target life, and make retrieving the dart a lot more work than it needs to be.  On the other hand, most people I know who like shooting guns, bows, slingshots, blowguns, and other projectile launchers like to know what their projectiles are capable of shooting through.  It’s FUN, as you’ll often hear reiterated at a website which is devoted to all kinds of ammunition penetration testing, The Box O’ Truth (where pistols, rifles, and shotguns are tested in interesting and memorable ways).  Please see above right for a link to The Box O' Truth.


The blowgun hunter who used bamboo darts to hunt squirrels and starlings at the links above, used Boarhog dart cones combined with thick bamboo skewers.  Cold Steel bamboo darts come with a plastic cone ready attached, although the bamboo shafts are somewhat narrower than the skewers used by the hunter.

Hunting Safety Tip

Always remember that wild animals may be vectors for diseases.  Use care and exercise proper hygiene during and after handling any animals you have shot.  It is probably best not to reuse ammunition if you are not able to adequately disinfect it after having used it to shoot an animal.  Many types of blowgun darts and pellets can be designed to be disposable after a successful hit on an animal.  If you don't want to use disposable darts or pellets, make sure you know how to clean and disinfect them adequately by rinsing and treating with chemical disinfectants and/or heat.  Also be sure that disinfectants will not later cause fumes or residue that would be unhealthy for use in a blowgun.

Another thing to be aware of when hunting is that an animal that appears to be stunned or dead can revive unexpectedly.  Don't put yourself at risk of a bite from an animal that suddenly revives.

Friction affects all projectiles when penetrating a target, but blowgun darts especially so.  The dart normally has a long, slender shaft with a narrow, sharp point.  The sharp tip doesn’t displace much target material, but simply wedges into the target, opening a small hole.  As the rest of the shaft follows through the hole or channel opened by the tip, the target material squeezes tightly against the shaft on all sides, creating quite a lot of friction.  If you are doing sport blowgun target shooting, you probably want this to happen.  It helps stop the dart before the stabilizer “cone” at the back of the dart hits the target face and causes unwanted damage to dart or target or both.


If, on the other hand, you do want to make penetration more efficient, one way to reduce the friction on the shaft as it’s passing through the “wound channel” opened by the tip, is to make the forward tip of the dart somewhat wider than the rest of the shaft, as on my trocar dart above.  A trade-off occurs, since making the forward tip wider makes the dart seem “blunter”, even if it still has a sharp point.  However, the decrease in friction may more than offset that, depending on the type of target the dart is being shot into.


When hunting with a blowgun, another aspect of penetration may become important, which is creating an “adequate wound channel” to dispatch a game animal or pest humanely, or in other words without needlessly prolonged suffering.  To this end, hunters often use use some version of a broadhead dart, with one or more sharp blades attached to the business end of the dart.  Usually the broadhead configuration looks pretty much like the triangular-shaped configuration we’d expect to see on one of Robin Hood’s arrows.  Fairly recently, I’ve seen some interesting alternative broadhead configurations posted by members at the Lefora Blowgun Forum  (LBF).  Another LBF member has demonstrated that squirrels and european starlings can be hunted or eliminated by using bamboo skewers without broadheads--- although it should be noted that the hunter in question used wide-diameter skewers for better terminal ballistic performance, and seems to be very accomplished in stalking skills and shot placement.  You can view some of his results at the links posted above right, but be warned that the photos are graphic.


Safety Tip

Use care when handling broadhead and spearhead blowgun darts.  The sharp points can easily draw blood, and certain darts may have true razor edges that can slice fingers and hands.  It is a good idea when storing darts in a quiver to make sure that there is something in place to guard the sharp points of the darts.  This help prevents dulling and damaging of the points and edges of the darts, and also helps prevent you from getting poked or cut by the darts.

Broadhead darts can be effective, yet come with several potential drawbacks.  First, they are fragile.  Jock Elliott, who writes a weekly blog on air guns, and is a long-time blowgun enthusiast as well, has reported that when testing penetration of certain types of commercially manufactured broadhead and spearhead darts, the sharp points of the tips had a tendency to bend or curl after being shot into “hard” targets such as a tin can.  I have encountered the same problem sometimes when shooting with various types of commercially manufactured “spearhead” darts, which normally have the forward end of the steel shaft flattened and shaped to produce the spearhead point.  Even when shooting into cardboard or fabric, the spearhead points have a tendency to bend or curl.  In addition to the points bending, broadhead darts are prone to snapping or breaking, especially the homemade versions made from various types of razor blades.  Usually breakage won’t occur on a soft target, but if a hunter misses a shot at an animal and the dart hits a tree limb or rock, blade damage is not unusual.  Even if blade breakage does not occur upon impact, retrieving broadhead blades from a target can be quite difficult.  It is easy to break blades or pull them loose from the dart during retrieval from a target.  Some hunters intend their broadhead darts to be disposable, making them economically from razor blades and bamboo skewers or wooden dowels.  An advantage to disposable broadhead darts is that when hunting, many types of so-called “pest” animals may be vectors for some very serious diseases, making some hunters reluctant to reuse darts that have hit such animals.  Even without the worry of exotic-sounding diseases, cleaning up a dart after a hit on an animal may not be easy.  On the other hand, the disposable dart approach may still leave a problem for someone who wishes to do extensive target shooting practice with broadhead darts before actually hunting with the darts.  It may be possible to at least partially solve the problem with a target designed to stop the darts without damaging them, yet release the darts fairly easily.  Such targets would rate at least one article devoted solely to them, however.


On the other hand, if a broadhead dart hits a tree limb and doesn’t break, retrieval of the dart is made even more difficult by the fact the hunter may have to climb a tree just to reach the dart, with all of the usual difficulties in extracting a  firmly embedded dart on top of the arboreal challenges.

Returning to the subject of friction, broadhead blades also may present a problem in terms of reducing penetration due to presenting increased surface area for contact with the target material, which will likely greatly increase friction.  One broadhead design which may address that problem, and which dates from quite a few years ago, was recently brought to my attention by an LFB member’s post .  An article showing the broadheads and the blowgun shooter who made them can be viewed at the "Blowguns Are His Business" link (above right).  The broadheads used were formed by bending thin, tough wire into a triangular shape and then sharpening along the leading edges of the wire  triangle.  This type of broadhead with gaps within the “blades” may have an advantage in helping the dart to fly straighter, since the design would give crosswinds less surface to push against, and would have less “wing” surface to cause air-planing deflection.  Upon impact with the target, the smaller surface area of the wire  triangle may also reduce friction while penetrating the target.   A photo in the article shows good penetration of one of the triangular wire broadheads on a  rattlesnake’s head.  The wire  triangle broadhead may also be somewhat less fragile than a broadhead formed from a flattened section of shaft.  The wire can be hardened, tempered, and springy, and made so more economically, probably, than trying to temper "spearhead" or "broadhead" blades that are made by flattening the front portion of a metal shaft.  On the other hand, using thin round wire to form such a "triangle" broadhead limits the cutting angle at the edge of the blades, and may also make it a bit problematic to make a heavy dart,if so desired, since the wire itself is relatively lightweight.


Enter the Trocar, Stage Left

A slightly different prototype of a straw-stabilized subcaliber trocar dart for a blowgun.  In this dart, the maximum diameter of the dart is substantially equal to the cutting diameter of the trocar's cutting edges.
A slightly different prototype of a straw-stabilized subcaliber trocar dart for a blowgun. In this dart, the maximum diameter of the dart is substantially equal to the cutting diameter of the trocar's cutting edges.

So, how to solve the crisis in blowgun performance brought about by the disadvantages of blowgun broadhead darts?  A question which is, I shamefacedly admit, stated in a somewhat melodramatic way, but which is nevertheless not without merit, and which is deserving of thoughtful attention.

How to solve the crisis?

Enter the trocar.

(ha ha, get it?  Enter?  as in, target penetration?  Holy pun, Batman!  O snap!  get it again!  Hole-y pun!  Hole-y!  As in terminal ballistics, again!!! (the long-suffering Caped Crusader shakes his head and sighs).)   

Ahem.  So anyway, where were we?  Oh yes...

So where does the trocar fit into the picture, when it comes to substantially improving the performance of certain types of blowgun darts?  

I think we've already seen enough to have a pretty clear idea.  First, a trocar is rugged and compact.  After shooting my various prototype trocar darts into cans and plywood multiple times, the sharp tips and edges have not bent or curled.  Granted, the tips and edges may have dulled a tiny bit-- although they certainly still feel just as sharp-- but dulling happens with any kind of cutting point/edge after being shot into a target.  So, already the trocar head has a big advantage compared to a spearhead or broadhead formed by flattening the end of a metal shaft, which results in a soft, easily bent point. 

Keep in mind, also, that the width of the trocar tip used on a blowgun dart could be wider or narrower than the approximately quarter-inch diameter Muzzy tips that I used for my prototype darts.  Trocar tips can also be formed in all kinds of other sizes of rods or shafts.  Even if the hole punched by a smaller-diametered trocar had the same area as the hole punched by a small, flat spearhead, the trocar would be more ruggedly constructed than the spearhead.  Second, although the cutting diameter of the three cutting edges of the Muzzy trocar tip I used is about a quarter-inch, and some commercial flat blade broadheads have a wider cutting diameter, the trocar tip can make a comparable or better wound channel for several possible reasons:  deeper penetration by the trocar ("all other things being equal"); three (or more) cutting edges of the trocar as opposed to just two cutting edges of the flat broadhead; and greater tissue displacement by the trocar, since the trocar makes a wound channel with an actual cross sectional area (in the case of the Muzzy point I used, a channel which a pencil would fit into), as opposed to the thin slits cut by a flat blade.  

To counter the trocar’s advantage in having more cutting edges, a broadhead with three or four blades, similar to those sometimes used in archery bowhunting, could be made for a blowgun dart.  I have seen 3- or 4-blade broadhead configurations which have been hand-made for blowgun darts, and some of them were beautifully crafted.  However, with one exception, I’ve never seen a three-blade or four-blade broadhead offered in a commercially made blowgun dart.  The one exception I don’t really count, however, because it was a “four-bladed” broadhead molded completely as a monolithic (or one-piece) component from plastic.  The plastic used to form the molded “broadhead” was tough, but could not compare with metal cutting blades. 

Even well-crafted homemade broadheads with three or four blades may still be somewhat fragile, and are more difficult to make than simpler flat broadheads.  Multi-blade broadheads also increase friction and reduce penetration, especially with wider cutting diameters, which with the limited kinetic energy of a blowgun dart, may cause performance failure.  To commercially make one-piece multi-blade broadheads with strong structure and sharp cutting edges would be a challenge, and to make such broadheads cheaply enough to be disposable even more of a challenge.  To make multi-blade broadheads with replaceable blades, as is common with many archery arrow broadheads, even though more complex, would be easier in terms of being able to form a fairly strong structure with sharp cutting edges by using standard razor blades to insert into the assembly.  However, the expense likely would be prohibitive.  Archers are willing to spend quite a bit of money for broadheads that are used to hunt big animals like deer.  Blowgunners are not likely to spend anything near as much for equipment to hunt smaller animals. 

Another disadvantage, by the way, to multi-blade broadheads is that it’s easy for the blades to scratch or score the blowgun barrel during launch.   The photos of the prototype trocar darts I've included in this hub show that it's possible to shape and form a trocar in such a way that the cutting edges extend substantially to the outer edge of the trocar's sides, yet do not contact the bore of the blowgun barrel in such a way as to cut, scratch or score the bore.

Speaking of cutting, scratching, and scoring, another reason why the trocar shines (for use as a blowgun dart point) is that the point and cutting edges of the trocar, although highly effective at target penetration, do not present such a potential for the user to accidentally cut his or her fingers, etc. during handling.   By contrast, more conventional broadhead darts of the type with flat blades that have true razor edges make it very easy for users to accidentally cut hands, fingers, etc. while handling and loading the dart.

As I’ve already shown, trocar tips can be used on both full caliber and subcaliber blowgun darts.  Trocar tips may be custom-made or manufactured with blowgun darts specifically in mind.  On the other hand, pre-existing trocar points, such as the replaceable, screw-on tips made by Muzzy and other archery component manufacturers, could also be exploited for use with blowgun darts provided with a shaft, stabilizer, or other portion designed to attach securely to the trocar points.  Such archery components are often of suitable dimensions and sufficiently lightweight to be utilized for blowgun applications.  In addition to separate points that attach to some part of a dart, a trocar tip may alternatively be formed integrally with the shaft, head, or other portion of a blowgun dart.  

A variety of trocar configurations are possible for use in/with blowgun darts.  A trocar may be formed directly into the end of a shaft.  Alternatively, a trocar may be a structurally separate component that fits, screws, glues, or otherwise attaches onto the end of a shaft or other portion of a blowgun dart.  A blowgun dart may simply be provided with a shaft, or some other component or portion, which has threads that may cooperatingly engage with the threaded section on an already available, or otherwise repurposed, archery component, such as the Muzzy trocar tips that I used in my prototype darts.  A trocar tip may attach directly to a stabilizer component, such as a molded cone often used in full caliber blowgun darts, or may attach to a tubular shaft-stabilizer or other type of stabilizer used in certain types of subcaliber blowgun darts.  The trocar head may have a portion that inserts into another portion of a blowgun dart, or alternatively or additionally, the trocar head may have some hollow portion into which some other portion of a blowgun dart inserts.  


Trocar tips may be formed by various machining processes that remove material.  Trocar tips may also be formed by other processes, such as casting, pressing, sintering, metal-injection molding, or powder-injection molding.  Tungsten is an example of a hard, durable material which may be formed with relatively sharp edges by sintering or molding, often without need for secondary machining to achieve sufficient sharpness to be useful for certain blowgun dart applications.    A one-piece trocar tip “assembly” may be especially suitable for adaptation to allow the trocar tip or head to be fairly easy to clean and disinfect using boiling or chemical disinfectants.   Shafts or stabilizers attached to such a one-piece trocar head may fairly easily be designed to be economical and/or disposable, especially the plastic straw shaft/stabilizer used in the prototype dart pictured above.


It should be kept in mind also, that for certain applications, the trocar tip does not have to exhibit the ruggedness and sharpness exhibited by the trocar tips I’ve used so far in my prototype darts.  Even without being able to penetrate quarter-inch plywood, a trocar-tipped dart may still be quite useful and quite adequate for certain types of target-shooting or hunting applications.  For this reason, trocar tips for use in blowguns could even be formed by some process such as swaging, which would likely leave the metal softer than some of the other manufacturing processes mentioned above.  Such trocar tips might be useful in several ways, especially where an inexpensive, potentially disposable dart may be used.  Trocar tips may be formed from other materials than metal.  Ceramics would be another type of material that could be readily processed to create trocar tips, with the potential to create adequately sharp cutting edges without the need for secondary machining.   It would even be possible, due to the compactness and solidity that a trocar may exhibit, to mold the trocar in plastic.  However, since it is preferable that the mass of a dart be sufficient in situations where penetration and energy delivery is important, it might be easier to mold a plastic trocar tip that fit onto a metal shaft, which would make it fairly easy and economical to make the overall structure of the dart strong and help give the dart sufficient mass to achieve satisfactory terminal performance.  An advantage over the type of molded plastic broadhead described above, is that with a metal shaft inserted into the end of a molded plastic trocar head, the diameter of the metal shaft may be almost as wide as the cutting diameter or widest diameter of the plastic trocar, so that the end of such a metal shaft may back and support almost the entire cross-sectional area of the plastic trocar (such a shaft may be hollow along some portion of its length, and still provide effectual support across almost the entire width of a plastic trocar point, especially if the trocar is molded as a solid member that inserts partially into the end of the shaft in a plug-like manner).  On the other hand, the plastic broadhead described above was backed and supported only along a narrow portion of its cross-sectional area by the slender metal shaft inserted into the back of the plastic broadhead, with the shaft having a much smaller diameter than the cutting diameter of the plastic broadhead.  Furthermore, the compact, pyramidal form of a molded plastic trocar would have many structural strength advantages over the thin, flat portions of a molded plastic broadhead.


In a blowgun dart or other blowgun projectile, the cutting diameter of the cutting edges of a trocar tip may define substantially the widest portion of the projectile.  Alternatively, there may be at least one other portion of the projectile which is as wide or wider than the cutting diameter of the trocar’s cutting edges.  A portion of the projectile which is slightly or somewhat wider than the cutting diameter of the trocar’s cutting edges may be useful in preventing contact of the cutting edges with the bore of the blowgun barrel, which might be scratched or scored by such contact with the cutting edges of certain types of trocar blades.  However, it should be noted here that when testing the prototype darts made with Muzzy brand trocar tips, in which the cutting edges extend all the way to the circumference of the round shank portion of the trocar, no problems were observed with cutting, scoring, or scratching the bore of the relatively soft aluminum barrel of the blowgun used to launch the prototype darts.  A wider projectile portion may also be useful in somwhat enlarging the puncture hole opened by the trocar’s cutting action, although as the projectile becomes wider, penetration depth may decrease.

Trocar tips formed in such ways described above that need little or no secondary machining to create adequately sharp cutting edges, may also be used with other types of projectiles than blowgun darts.




Full caliber, conical shell sabot can be seated by inserting into the hollow stabilizer shaft of the subcaliber trocar dart.
Full caliber, conical shell sabot can be seated by inserting into the hollow stabilizer shaft of the subcaliber trocar dart.
The yellow dart above uses the top trocar head, which has a brass rod backing the trocar tip.  The bottom trocar head was used in the can penetration tests shown at the beginning of this hub.
The yellow dart above uses the top trocar head, which has a brass rod backing the trocar tip. The bottom trocar head was used in the can penetration tests shown at the beginning of this hub.

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