18
Improving the Barrel One of the most important aspects of any launcher is the barrel. And, as with any other launcher part, this, too, can be upgraded and modified. The following will give details and examples of the most common barrel upgrades for launchers. ~Hubb~ Table of Contents Sleeving PVC ................................................................................................................................................ 1 Rifling a Barrel ............................................................................................................................................... 2 Barrel Honing and Polishing.......................................................................................................................... 5 Barrel Crowning ............................................................................................................................................ 6 Muzzle Breaks............................................................................................................................................... 7 Hopup ............................................................................................................................................................ 8 Spud Cutter ................................................................................................................................................. 10 Barrel Stops and Detents ............................................................................................................................ 11 Barrel Supports ........................................................................................................................................... 12 Breech Loading ........................................................................................................................................... 13 Wadding and Sabots ................................................................................................................................... 16 Common Projectiles with Barrel Match ....................................................................................................... 17

Improving the Barrel

Embed Size (px)

DESCRIPTION

improving spud cannons

Citation preview

  • Improving the Barrel

    One of the most important aspects of any launcher is the barrel. And, as with any other launcher part, this, too, can be upgraded and modified. The following will give details and examples of the most common barrel upgrades for launchers.

    ~Hubb~

    Table of Contents

    Sleeving PVC ................................................................................................................................................ 1

    Rifling a Barrel............................................................................................................................................... 2

    Barrel Honing and Polishing.......................................................................................................................... 5

    Barrel Crowning ............................................................................................................................................ 6

    Muzzle Breaks............................................................................................................................................... 7

    Hopup............................................................................................................................................................ 8

    Spud Cutter ................................................................................................................................................. 10

    Barrel Stops and Detents ............................................................................................................................ 11

    Barrel Supports ........................................................................................................................................... 12

    Breech Loading ........................................................................................................................................... 13

    Wadding and Sabots................................................................................................................................... 16

    Common Projectiles with Barrel Match ....................................................................................................... 17

  • ---Sleeving PVC---------------------------------------------------------------------------------------------------------------------- Sleeving PVC pipe can be a frustrating and time-consuming task, however, it becomes necessary to do so in some circumstances. Sleeving PVC pipe has two primary functions. First, it strengthens and stiffens the barrel. Secondly, and probably the biggest reason, is that it allows the use of certain types of projectiles that would otherwise not be able to be used.

    There are two methods of sleeving pipe; direct insertion and modified insertion.

    Direct Insertion Direct insertion is the method in which a male pipe (inner pipe) is inserted into a female pipe (outer pipe) without the need for modification and is usually desirable to increase durability of the barrel.

    A prime example of this type of sleeving is seen in most golf ball barrels. Golf balls fit into 1.5" Sch160 (SDR), which fits into 2" Sch80 pipe, as seen to the right.

    Modified Insertion Direct insertion is very convenient, however, in most circumstances, a male pipe will not fit into the female pipe correctly. It may either be too small or too large for a correct fit. To fix this problem, modified insertion is needed.

    When the male pipe is too small, simply wrap tape or other material around the pipe until it has the correct diameter. It is best to wrap the tape in the same direction throughout. Once complete, insert the male pipe into the female pipe and begin twisting the pipe in the same direction as the tape (as not to wrinkle it) until the pipe is completely inserted. This is used to strengthen the barrel, as the barrel's ID will be the same as the male pipe, as in direct insertion.

    To sleeve a pipe to make a new diameter, it needs to be split and resized. Try to make the split as straight as possible. A table saw is ideal for this. Now, it is a good idea to make the split just wide enough to fit into the female pipe with a minimal gap. The calculator will assist in determining the width of the split to minimize the gap.

    The easiest way to do this (if easy is the word) is to rub a slow drying epoxy into the pipe walls in the split. Lubricate the interior of the female pipe with dish soap or similar. Now, clamp one end of the male pipe so that the edges of the split touch and insert it into the female pipe. Place the opposite end of the female pipe onto a soft surface and use a rubber mallet to hammer the male pipe in place. Continue moving the clamp up the length of the male pipe to aid in sleeving. Allow the lube and epoxy to dry.

    The epoxy is not necessary needed, however, it will make sure there is no gap present when the sleeving is complete. It will also squeeze a little onto the interior of the female pipe, making sure it holds better. If epoxy is used, be sure to property hone the barrel (described below) to make sure no epoxy is present on the interior.

    In either of the sleeving methods described above, it is always a good idea to make the male and female pipes longer than the desired barrel to allow for any errors that may present themselves.

    1

  • ---Rifling a Barrel-------------------------------------------------------------------------------------------------------------------- A rifled barrel can greatly enhance the accuracy of the projectile and puts the "coolness factor" of a launcher through the roof. Too bad it is not the easiest modification one can make to a barrel.

    There are several methods one can use to rifle a barrel, most of which require special, expensive tools. Most of us do not have these tools, so we must improvise.

    The standard "Poor Man's" rifling still requires a tool, but this tool can easily be made.

    Step 1: Setting and Marking the Angles - 360o protractor - ruler - pencil or other marking devise - paper - pipe or dowel that can fit into the desired barrel and is approximately 6 inches longer than the barrel

    The first thing that needs to be done is to determine the number of grooves that are to be in the barrel. A good number to start with is four, however, no more than six grooves will be needed. Once this has been chosen, use the calculator to calculate the angle that each groove should be set.

    Place the protractor onto the piece of paper and mark each angle indicated by the calculator. Also, place a mark in the center. Once the marks are placed, removed the protractor. Now, use the ruler to draw a straight line from each mark to the center mark.

    From here, place the pipe or dowel over the center of the lines. Use the pencil or marking devise to mark where each line connects with the pipe or dowel. The angles have now been marked on the tool.

    Step 2: Building the Tool - 16d nails - file / hacksaw / rotary tool with cutoff wheel - drill and bit a little smaller than the diameter of the nails - epoxy - ruler - pencil or other marking devise

    Use the ruler to draw parallel lines up the shaft of the tool. It is imperative to maintain the lines as parallel as possible, so take time with this. Start at 1" from the bottom of the shaft and place a mark on one of the lines. Measure up 1/4 inch and place a mark on the line next to the first. Measure another 1/4 inch up the shaft and place a mark on the line next to the second (going in the same direction). Repeat this process until all of the lines have a mark.

    2

  • At each mark made, drill a hole through the shaft. Again, it is imperative to make these holes as straight as possible, so use a drill press if one is available. Once the holes have been drilled, place epoxy under the head of the nails and work them into the holes. If a pipe is used, fill the end portion of the pipe with epoxy to add strength and hold the nails better. Allow the epoxy to fully cure before continuing to the next step.

    Step 2: Tuning and Testing the Tool Once the epoxy has cured, it is time to trim the nails to fit the desired barrel. Begin trimming each nail slowly. The goal is to trim the nails so that they will be just a bit longer than the inside diameter of the barrel. Also, do not sharpen the nails. This will make the grooves cut wider, which will allow the projectile to catch and spin better.

    Throughout the nail trimming process, it is best to test the rifling tool to get the right length. Obtain a scrap piece of pipe that is the same as the barrel. Insert the tool and pull through, taking note on the grooves that are made. Adjust the nails accordingly. When the nails are at the proper length to make the correct sized grooves, it may help to wrap the bottom 1 inch of the tool with tape until it is equal to the barrel diameter. This will help guide the tool evenly throughout the barrel.

    Step 3: Final Preparation and the Rifling Process - clear tape - string - pencil or other marking devise - tape measure

    The next step in the rifling process using this tool is to set the tool to cut the correct twist : length ratio in the barrel. To determine the ratio, refer to the calculator. Once the ratio has been determined, tie the string tightly around the top nail. Measure from the nail the string is tied to up the shaft of the tool to equal to the barrel length. Place a mark on the shaft at this point. Begin tightly wrapping the nail up the length of the tool until it reaches the mark just made on the tool. Tape the string in place. About every inch or so down, add another piece of tape to hold the string securely.

    Set the tool aside and place a small mark on the muzzle edge of the barrel. Feed the top of the tool through the breech end of the barrel pipe and bring the top out the muzzle end. Line up the string with the mark made onto the barrel. Begin working the tool into the barrel. Do this slowly and carefully, maintaining the tool as parallel with the barrel as possible and keeping the string in line with the mark at all times.

    3

  • Rifling Metal Pipe Rifling metal pipe, such as copper or aluminum, can be done in the same manner described above, however, it takes a bit more time to work the tool through the barrel. It is also advisable to use another tool instead of building one in the manner above.

    Start with a hex head bolt that has a head just slightly larger than the inside diameter of the barrel. Begin filing the bottom edges of the hex portion of the bolt. The bottom edge is the edge closest to the shaft. Make it the same diameter as the barrel's inside diameter. At the top of the bolt, leave a small part of the hex still in tact. The edges of the hex will be what cuts the rifling. The head of the bolt should be similar to the image to the right. If the hex portion is just too large to fit into the barrel, the flat surfaces of the hex portion can be filed until the correct width is obtained, just be sure to file them evenly.

    Experiment with the thickness of the hex head to achieve the best results (a thicker head will make wider grooves, but will also be harder to work). Note that each point on the head can be filed to an angle, however, without precision measurements, this will probably hurt rather than help.

    Once the bolt head is complete, affix it to the rifling shaft. It is advisable to use a metal tube, as plastic or wood may break under the pressure needed to rifle. Run the shaft of the bolt into the end of the tube. If the shaft is too thick, sand it down. If it is too thin, wrap tape around it to thicken it up.

    Once the bolt has been placed into the rifling shaft, drill a hole through the tubing and bolt shaft. Place a roll pin or other similar object through the hole to securely hold the bolt into the shaft. From here, follow the steps above to determine the rifling ratio, install the guide, and use the tool. If done correctly, the results should be similar to the image.

    4

  • ---Barrel Honing and Polishing------------------------------------------------------------------------------------------------- The purpose of barrel honing and polishing is to smooth out any imperfections within the barrel and make the inside surface of the barrel as smooth as possible. This is a very easy process to perform and the benefits will be noticeable. In all honesty, this procedure is recommended on any barrel, whether it is rifled, metal, plastic, or just plain. There are many methods of barrel honing and polishing, however, for the best (and fastest) effect a tool should be used.

    Step 1: The Boring / Polishing Bit - Piece of pipe that will snugly fit over the threaded rod, at least 3 inches long - duct tape - fine grit (800 to 1000 grit) sandpaper OR clean dry cloth (white)

    This bit is designed to be used for either polishing or boring and can be changed if necessary. Start by wrapping duct tape around the small piece of pipe. Continue this until it equals the diameter of the inside of the barrel. Once complete, cut a strip of sandpaper or cloth that is approximately twice as wide as the bit. Begin wrapping the sandpaper or cloth tightly around the bit, leaving about the same amount of overhang from the bit then tuck the overhang into the piece of pipe.

    Step 2: Building the Boring / Polishing Tool - threaded rod at least 3 inches longer than the barrel - rotary tool with sanding wheel - 2 of each; nuts, flat washers, lock washers that fit onto the threaded rod

    The first order of business is to add a chucking end onto the tool. Choose an end and cut a triangular shape onto it that is about an inch long. Now add (in this order) a nut, a lock washer, and a flat washer onto the opposite end. Insert the bit onto the threaded rod, making sure the overhand of the bit does not come out of the piece of pipe.

    Add (in this order) a flat washer, a lock washer, and a nut onto the same end. Adjust this nut so that it is approximately 1/4 inch from the end of the threaded rod. Tighten down the other nut onto the bit.

    Step 3: Using the Tool To use the tool, simply chuck the tool into a handheld drill appropriately and work it back and forth in the barrel. Be sure to bore the barrel before polishing it.

    Boring To bore the barrel to clear it of any imperfections, use the boring bit. Continue this procedure until the desired smoothness is obtained. Remove the tool and thoroughly wash the barrel to clear it of any dust. When boring a rifled barrel, take precaution as not to damage any of the rifling.

    Polishing Use the polishing bit. If the barrel is metal, use an appropriate polishing compound on the bit. Otherwise, use water. Work the tool in the same manner to apply the polish or water. Replace the cloth on the bit with a clean one. Work the dry cloth into the barrel in the same manner and remove the boring tool. Continue this process until the bit comes out of the barrel clean.

    5

  • ---Barrel Crowning------------------------------------------------------------------------------------------------------------------ As a projectile leaves the muzzle end of a barrel, so does the gases that are propelling it. It some circumstances, the gases may hit one of the sides of the projectile, causing it to veer slightly. This, of course, throws the projectile off target, which is bad, right?

    Crowning is the process of uniformly beveling the muzzle end of the barrel. This allows the gases behind a projectile to escape more evenly around the projectile rather then directly behind it, drastically cutting down the effect described above. This upgrade is recommended for every type of barrel and is a very simple process to complete.

    In order for a crowned barrel to work right, the crowning has to be made right. All that is needed is some fine or medium grit sandpaper and a ball that is slightly larger than the barrel's inside diameter.

    Crowning a PVC Barrel Golf balls work well for 1.5" Sch40 and tennis balls work well for 2" Sch40. Simply wrap the sandpaper tightly around the ball and rotate the ball back and forth at the muzzle until a uniform bevel is formed. Once the barrel is formed, polish the crowning to make sure the surface is as smooth as possible.

    Crowning a Metal Barrel Crowning a metal barrel is just as simple as crowning a PVC barrel, but takes a bit more time. For metal barrels, however, a rather hard ball should be used so as not to be deformed when pressure is applied. Marbles that are slightly larger than the barrel's inside diameter are ideal.

    Apply some lapping compound to the marble and work the marble on the muzzle end of the barrel. When done, be sure to wash away all the lapping compound with soap and water.

    Alternative Crowning Another method for crowning is to use a beveled pipe cap that is the same size as the barrel. This procedure, however, is a lot easier to mess up, as the cap must be as parallel with the barrel as possible during the entire process.

    One other method, which should only be used as a last resort, is to use sandpaper or a rotary tool by hand. Although it is possible to get it right using this method, it is sure to cause uneven spots throughout.

    Note: This is a useless procedure if the crowning is not straight and the muzzle is not cut square, so take your time with this.

    6

  • ---Muzzle Brakes-------------------------------------------------------------------------------------------------------------------- A muzzle brake, or porting, redirects the gases of the launcher when it is fired. This, essentially, does the same as barrel crowning, as well as reduces recoil and muzzle climb. Please note, however, that these effects are going to be minimal on a launcher. The real reason one chooses to place a muzzle brake on a launcher is to increase the "coolness factor."

    Muzzle brakes come in a vast array of sizes and shapes, but the most basic form is simply drilling a series of holes through the muzzle end. If this process is done, be sure to properly bore the barrel to make sure there are no imperfections at the holes.

    Another common type of muzzle brake is achieved by adding a coupling to the muzzle end of the barrel. Holes can be drilled through the coupling in the same manner as above if desired. This type of muzzle break tends to look more professional than just simply drilling holes in the barrel.

    Another form of muzzle brake is adding a tee or cross to the end of the muzzle. If a tee is used, be sure to make the exit hole slightly larger than the bore diameter, so as not to interfere with the projectile.

    7

  • ---Hopup-------------------------------------------------------------------------------------------------------------------------------- A hopup system on a barrel can greatly increase the range a projectile will travel and will also increase the accuracy of a shot. It does so by putting backspin on the projectile to control the Magnus Effect. It is very commonly seen on many airsoft and paintball guns.

    There are two things to remember when determining to use a hopup system. (1) It will not work with a projectile that is not perfectly round and (2) it will defeat the purpose of a rifled barrel completely and will more than likely work against both upgrades, completely killing any hope of accuracy.

    There are many different ways to incorporate a hopup system into a barrel, but each hopup system falls into one of two categories; non-adjustable and adjustable. Both have advantages and disadvantages, which I will attempt to describe below as well as including both versions that I've had the best luck with.

    Non-Adjustable Hopup A non-adjustable hopup system is just that, not adjustable. It is easier and cheaper to construct and is less prone to errors. It has the disadvantage (besides being non-adjustable) of being less durable.

    The following hopup is completely concealed in the barrel, allowing for muzzle upgrades if necessary and is as simple as adding a piece of electrical tape to the interior of the barrel. In fact, that is all that is needed. Place a strip of the tape about an inch long in the muzzle end of the barrel. Make the tape run parallel with the barrel and make sure it is at the exact top. Add additional pieces to increase the effectiveness of the hopup. Once complete, be sure to check the hopup periodically when in use and replace the tape if necessary.

    Adjustable Hopup An adjustable hopup has the advantage of being adjustable to increase or decrease the Magnus Effect as desired. The below version is also much more durable than the previous. The downside is that it is a bit harder to construct and requires permanent modifications to the barrel.

    Begin with a coupling the same size as the barrel. Remove the lip of the coupling so that the barrel will slide through it. Slide the coupling over the muzzle end of the barrel so that the coupling is flush with the end of the muzzle. Mark the opposite end of the barrel and remove the coupling (for reference, the measured length of the barrel muzzle to the mark should be the same as the length of the coupling). From here, measure from the mark towards the muzzle about 1/4 the way and place another mark.

    On the muzzle end, at the exact top, measure a small width and draw straight marks from these points to the 1/4 inch mark. The strip should be about 1/4 as wide as the diameter of the barrel. Slowly and carefully trim out the barrel around this strip. Be sure to make the cuts as straight as possible. When complete, rough the inside surface of the slit with sandpaper.

    8

  • Set the barrel aside and get the coupling. Decide which end will be the muzzle end and which is the back end. Now, obtain four short screws and a drill with a bit the same diameter as the screws. Drill one hole, as straight as possible just a little bit into the coupling at the muzzle end. Drill three holes through the back end of the coupling in the same manner. Work the screws into all of the holes to cut threads into them or use a tap. The coupling will now be called the hopup muzzle.

    To install the hopup muzzle, just insert it onto the end of the barrel muzzle so that the muzzle end of the hopup and the barrel match. Rotate the hopup muzzle so that the screw hole lines up with the strip in the barrel. Install the back end screws and tighten them down to hold the hopup muzzle in place. Now, install the muzzle end screw. To adjust the hopup, tighten or loosen the muzzle screw.

    For the most part, backspin is going to be dependant on the velocity of the shot. The purpose of the adjustable hopup system is to allow the hopup to be adjusted to fit the velocity, providing the maximum amount of backspin. Adjust the hopup so that the Magnus Effect is present (trust me, you'll know) but no further. Adjusting the hopup beyond that which is needed will begin to affect accuracy and cause the projectile to lift upwards rather than travel straight as intended.

    9

  • ---Spud Cutter------------------------------------------------------------------------------------------------------------------------What better way to introduce a spud to a barrel than have it automatically cut to the shape of the bore when inserted? The spud cutter, or muzzle knife, or barrel knife, or...whatever the name... does just that; it shapes the projectile to fit the barrel just right. This is one of the most commonly used upgrades for a potato launcher to date, is the most recommended on a potato launcher, and is fairly easy to build.

    Essentially, there are two types of spud cutters: An integrated cutter, and a supplemental cutter. Each have their advantages, and it is user preference as to which would be used.

    Integrated Cutter This is an edge cut on either the muzzle end or the breech end of a barrel, depending on how the projectile is to be loaded. Sandpaper, a rotary tool, a file, or anything really, can be used to do this. Simply push the spud onto the edge and it cuts it to shape.

    Supplemental Cutter This is a separate part, not integrated into the launcher. Usually, it is a scrap piece of pipe the same size as the barrel. Sharpening this pipe is done in the same manner as the Integrated Cutter. Once the spud is cut, it is then inserted into the barrel.

    Upgrades The biggest problem with barrel knives is that most of them are made of plastic. This will dull over time. To combat this, some have serrated their spud cutters and even made them from metal. Again, this is all user preference and, for the most part, not needed as the cutter can always be resharpened.

    Crowning goes great with an integrated spud cutter, as it will make the projectile cut to just a slightly larger diameter than the bore. This, in turn, will allow just a bit more pressure to build up before launching the projectile, producing a higher muzzle velocity.

    10

  • ---Barrel Stops and Detents----------------------------------------------------------------------------------------------------- A barrel stop and a detent do essentially the same thing; they keep the projectile from moving past a certain point.

    Barrel Stops A barrel stop is commonly seen on muzzle loading combustion launchers to keep the projectile from entering the chamber. In fact, a barrel stop is nearly essential on these types of launchers. They are not needed on pneumatic or hybrid launchers, as the valve actually acts as a barrel stop.

    Many things can be used as a barrel stop, but nails or screws are the most common, as it is only a matter of placing the nail or screw through a hole where the chamber meets the barrel. Some things to note, however, is that the barrel stop should completely stop the projectile from passing by it while still allowing maximum flow of the gases from the chamber to the barrel.

    Detents A detent is used on breech loading launchers that fire spherical projectiles. It keeps the projectile from rolling down the barrel. The detent, unlike the barrel stop, must keep the projectile from rolling down the barrel while it is at rest, but still allow it to pass by when the launcher is fired. This sounds complicated, but is actually quite simple to accomplish.

    An o-ring works well for a detent. Cut two adjacent slits into the barrel and place an o-ring over the slit so that it slightly protrudes into the barrel.

    Another type of detent is to apply dimples into the barrel. This works, but is a bit less durable than using an o-ring. The advantage is cosmetic. It is far less noticeable than an exposed o-ring (although the o-ring can be covered). To make, use a small blunt object to push or hammer the pipe in near the breech. This will create dimples in the pipe.

    11

  • ---Barrel Supports------------------------------------------------------------------------------------------------------------------ Sometimes, a barrel will wobble when the launcher is fired. The immediate effects of barrel wobble is that accuracy can and probably will be thrown off. Long term effects include the launcher becoming weaker and weaker, eventually leading to failure. In an over/under configuration, this also puts tremendous stress on the connection fittings, which may cause them to fail on the first shot.

    To solve this problem, a barrel support should be added to the launcher. A barrel support is exactly that; a devise to support the barrel. It generally connects the barrel to the chamber of an over/under configuration. This leads to much less stress on the barrel and the launcher in general and also keeps the barrel in line with the target to enhance accuracy.

    There are two different types of barrel supports. The first is simply placing a short piece of pipe or other object between the barrel and chamber and simply clamping the barrel and chamber to the support. This can be done by wrapping tape around it or using a large hose clamp. Another method is to use pipe fittings with a tee and glue or weld the pieces together.

    This method of support works great, however, it can only be used with muzzle loading launchers. To make this type of devise work with a muzzle loading launcher, simply make the support either removable or make the support where the barrel can pass through it, such as this launcher.

    12

  • ---Breech Loading------------------------------------------------------------------------------------------------------------------ Breech loading is a very common barrel upgrade and for good reason. It allows a projectile to be loaded directly into the breech end of a barrel. This is also another upgrade that is only limited by the imagination of the builder. Here, I will cover the methods that are most commonly seen.

    Screw Adapters A simple breech loading mechanism can be easily made using a male and female adapter. By placing one adapter on the barrel and the other on the chamber, they can be easily separated by unscrewing them from each other. Once the projectile is loaded, the chamber and barrel are screwed back together.

    Camlock Adapters A male camlock fitting has an appearance resembling a large male quick disconnect. A female camlock fitting has two metal levers on the outside of it. To use, the male fitting is inserted into the female fitting and the levers are pushed to the closed position, i.e. in towards the fittings. To fit them onto the chamber and barrel, they can be cemented or screwed in place. This method does the same thing as the screw type breech loader, however, it does it much easier and faster. It also presents an airtight seal...something the screw adapter can't lay claim to.

    Bolt Action A bolt action breech loader has the advantage of being faster than the previous two methods, while increasing "coolness factor" at the same time. This method is commonly seen on rifle type launchers. It, however, has the disadvantage of being more difficult to implement than the previous two, as well as somewhat limiting the projectile.

    It consists of the bolt and a body. The bolt is most often the same as the barrel sliding in the body and allowing a projectile to be inserted. The bolt is slid back towards the chamber and locked into place, usually with a rotating bolt action type lock.

    13

  • Cartridges This method involves using preloaded cartridges for the projectile. This is commonly seen in paintball and airsoft, as it tends to be a very fast method of getting the next shot off, which tends to be desirable for these games.

    The locking mechanism for a cartridge loading system usually resembles that of a bolt action breech load.

    Did I mention the "coolness factor" for this one?

    Coupling Method This method is a common type of breech load, and is fairly simple to use. It is used more for uniform projectiles. A hole or gap is cut into the barrel near the breech end and covered with a coupling that has been modified to slide over the barrel. O-rings can be used on both sides of the hole to provide an airtight seal.

    Break Barrel This is a rather uncommon breech loading method, however, it has several advantages over other methods. It has universal projectile capabilities that are present in screw type and camlock breeches while having the speed capabilities of a coupling breech. All of this is topped off by having a "coolness factor" equal to, or surpassing that of, a bolt action breech. It can even use cartridges if designed right.

    14

  • Unions This is primarily used to implement burst disks into a launcher and is the most common method used on hybrid launchers. A union is a screw together type assembly and can be fitted to a chamber and barrel in the same manner as other fittings. Unions are screwed together, in much the same way as screw adapters, however, they tend to be a little faster.

    Ball Valve Breech Loading This type of breech loading is unique in that it uses a ball valve. A ball valve is placed on the barrel, near the breech end. A hole is drilled into the side of the ball valve. To operate, the valve is closed, a projectile loaded, then the valve opened. Using this type of breech is very simple and very fast. The disadvantage to this type of breech is that it is usually projectile specific. It can only handle a projectile of a certain size, shape, and length.

    Butt Loading This is a rare type of breech load that is normally seen on over / under launchers. It can also be used on coaxial launchers as well. The barrel is sealed with some sort of plug. The plug is removed, the projectile inserted, then the plug reattached.

    Hoppers A hopper is most commonly seen on airsoft and paintball guns, however, some launchers use this breech loading system. It has the fastest loading of other breech load systems, and can be adapted to auto-reload by use of a detent. This breech loading system performs best with round, uniform projectiles.

    15

  • ---Wadding and Sabots----------------------------------------------------------------------------------------------------------- Sometimes, a projectile just will not fit inside a barrel. If it is fired through the barrel, air will escape around it. This will cause the velocity of the shot to be drastically reduced, which will, a lot of times, lead to the projectile not even leaving the barrel. This may also lead to the projectile bouncing around inside the barrel as it travels outwards, which may cause damage to the barrel. And forget about an accurate shot.

    To fix this problem, wadding or a sabot should be used.

    Wadding Wadding is a sort of primitive way to help seal a projectile. It is usually a wad of some material that is placed in the launcher before the projectile. When the launcher is fired, the air seals the rear of the wadding, which then forces the projectile out the barrel. Once the projectile and wadding exit the barrel, the projectile continues forward but the wadding falls away, usually within feet of the barrel.

    Common wadding material includes paper or plastic bags, tissue paper, small discs and even water.

    Sabots A sabot is a type of wadding that wraps around the projectile in most circumstances. It is superior to wadding in that it also helps to seal the projectile completely. It cradles the projectile and usually leads to a lower coefficient of friction in the barrel. It is also one of the primary ways to fire multiple projectiles at once, such as several paintball or airsoft rounds through a larger barrel.

    When fired, it acts very similar to wadding. It often breaks away from the projectile, leaving the projectile(s) to continue on.

    On the other hand, sabots are a bit more difficult to prepare. They usually consist of a type of wadding affixed to walls. Sometimes, the walls are split, making the sabot easier to peel away from the projectile once fired.

    Common sabots are usually made of styrofoam cups or other cap-like devises, such as spray can caps in 2" Sch40 pipe. To construct a simple sabot using a cup, simply insert the cup into the muzzle end of the barrel. When it has been snugged down and is square with the muzzle, use a sharp knife to cut away the cup end that is exposed.

    16

  • ---Common Projectiles with Barrel Match---------------------------------------------------------------------------------- Of course, the most common projectile to use in a potato launcher is, well, a potato. 1.5" and 2" Sch40 PVC are both very common barrels to use, 2" being used for larger projectiles. Also, any other sort of produce can be used, and each one usually requires the use of a spud cutter to match the bore of the barrel.

    Listed are other commonly used projectiles and the barrels used for such.

    Golf ball 1.5" SDR PVC (usually sleeved inside 2" Sch80 for durability) 2" Sch40 PVC sleeved inside 2" Sch40 PVC Tennis Ball 2.5" Sch40 PVC Paintball .5" SDR PVC .75" CPVC Airsoft BBs 6mm brakeline airsoft barrel from gun Copper/Steel BBs 4.5mm brakeline bb barrel from gun Marbles This varies, as there are many different sizes of marbles 12g CO2 Powerlet .75" Sch80 PVC AAA Batteries 3/8" Type K copper AA batteries 1/2" Type M copper C batteries 1" Sch40 D batteries 1.25" Sch40 12 oz soda can 3" Sch40 PVC sleeved inside 3" Sch40 PVC Nerf Mini Vortex 2" Sch40 PVC

    Molds - Molds are similar to shaped projectiles (such as potatoes or other produce), however, they usually involve the use of some type of liquid. This can be ice, wax, cement, etc. A molded projectile can be made to fit any type of barrel. Generally, however, a molded projectile can only be used once, as it will break apart upon impact.

    17