Customer Questions - FAQ

• What’s the difference between a Railgun and a basic gun?
  
  Railguns are unique in the sense that they have an extended "rail" incorporated into the aluminum barrel all the way along. This rail supports the spear the full length of the barrel and continues on into the muzzle. The rail barrel tube is also much stiffer and stronger than a normal tube because it is thicker-walled and has a slightly bigger diameter. The integrated rail adds further strength. We also use aircraft grade aluminum when the barrels are extruded. This gives the barrel even better strength and stiffness, enabling it to handle strong rubbers and be used in longer lengths without flexing. It is basically stronger and stiffer than wood of the same diameter.
   
• Would the extra Aluminium not increase the barrel weight making it heavy to handle?
  
  It does increase the barrel’s dry weight, but we have increased the internal diameter of the barrel to allow for a greater air cavity, giving the gun more buoyancy, therefore compensating for the extra weight and making it feel light in the water.
  
   
• Why is the spear in a railgun shorter than in a standard gun?
  
  The support given by the rail allows the gun to use a shorter spear than a normal gun. To make a standard gun accurate, the length of spear has to be such that the section protruding from the muzzle will counter the sag in the middle section. This will be apparent when too short a spear is used, because it will shoot high. The opposite is true if too long a spear is used, as it will shoot low.
  
   
• What are the advantages of a shorter spear than normal?
  
  Having a shorter spear in relation to your barrel length means less drag at the end when swinging the gun onto a fish, improving maneuverability. The shorter spear is also stiffer, and therefore less likely to bend.
  
   
• How does an incorrect length spear affect the accuracy of a standard gun?
  
  The spear in a standard gun is only supported in the mechanism and in the muzzle. To see this visually, try setting a long spear up on a table, lying it flat, and supporting it at both mechanism end and barb end with a matchbox. Now look along the spear, basically sighting along it from the mechanism end. You will see a prominent sag in the middle. The amount of sag you see will depend on the length, diameter and the stiffness/ tensile strength of the spear. If you move the matchbox at the barb end back towards the other box, the spear sag in the middle will decrease. At a point where the length of spear ahead of the moving box in roughly 1/3 of the total, the sag in the middle will be approximately equal to the now sagging end piece. This is again only really a factor with long spears.
   
• Why can’t I put a support for the spear on the barrel and achieve the same result as a rail?
  
  With supports on the barrel the spear tends to drop out of the mechanism when fired and "bump" over the support, causing an exaggerated wobble on the spear. This wobble will slow the spear down a great deal while it is traveling. With a rail this wobble is eliminated totally because the spear is supported all the way along and does not have a sag at the end because it is shorter than normal.
  
   
• Why does my railgun seem to shoot the spear much faster and straighter than my standard gun?
  
  On a railgun there is no sag in the middle of the spear because of the rail supporting it, and the length protruding out of the muzzle need only be short, therefore the spear weighs less. The drive ratio of the rubber is now much improved because the length relation of barrel to spear has increased; therefore more speed is attained without increasing the rubber strength. Another reason the spear is faster is because the spear does not wobble because it is supported level before being fired, and remains straight once momentum is achieved. Wobbling of a spear develops with a standard gun when the spear has a slight sag in the middle along with sag at the end. The moment the trigger is released the spear tends to "buck" creating a wobble when fired from a standard gun. This obviously creates more friction and therefore slows the spear down a great deal.
  
   
• Why does my standard gun lose accuracy when I fit stronger rubbers?
  
  Some standard barrels tend to bend when under big loads from strong rubbers, especially so with long guns. When you pull the trigger of a gun that has this problem, you release the compression on the barrel, which then straightens out. Because you are holding the handle at the back, the muzzle then moves the most, downwards, which in turn chops down on the spear as it is leaving the gun. This creates a bad wobble that slows the spear down and makes it very inaccurate.
  
   
• Is the railgun not noisier than a standard gun because of the spear being against the barrel?
  
  Noise is definitely a factor underwater. A railgun is no different to any other, and it does make a noise. Fish are affected by noise but more so by the "pressure wave" that the rubbers put out when the gun is fired. The pressure wave moves through the water at the same speed as the sound of the gun and with greater force. No matter how quiet you make the gun you still cannot eliminate the shock wave the rubbers will create when fired. Some divers put a neoprene sleeve around their standard barrel to try to silence it. The problem with this is that the spear rests on it, therefore affecting the performance of the gun. The performance and "wet weight" of the gun will also vary at different depths because the neoprene sleeve will compress the same way your suit does.
  
   
• Does the spear resting on the rail not cause friction on the spear and slow it down?
  
  When in the water the rail and spear are both wet. Once the spear gets going it will slide on a thin film of water which eliminates the possibility of it touching the barrel. A well-used railgun shows no wear in the rail, which it would show if there was significant contact friction. This is similar to the way that a slipper bearing or a beach skimboard work.
  
   
• Why do most railgun uses only use one rubber?
  
  Using one rubber on a gun helps with loading speed and reduces the drag when trying to swing the gun on a fish. This is only really a factor when using a long gun such as one with a 1.2m barrel. A long gun, with multiple rubbers, creates drag that will hinder your ability to swing.  
• Why do railguns not have screw-on rubbers in the muzzles?
  
  The idea of a single looped rubber makes it more economical to produce and therefore less expensive to the diver. In actual use the extra rubber that goes around the muzzle gives extra drive. In other words, the rubber can be made a little shorter than that of a screw on set up, therefore giving you a longer drive that will give more speed to the spear. These muzzles are also designed to enable the diver to exchange rubbers easily in the water without tools if he is carrying a spare rubber clipped to his float.
   
• Why are single fixed barbs most common on railguns?
  
  We have found that the vast majority of spearfishermen have at one time or another used or tried a drop head (slip tip). They virtually all change back to a single barb for a variety of reasons, the main reason being accuracy. Here we have found that it is very difficult to get the drop head to sit on the tip of the spear without any play (basically sideways movement). If you can get it to fit without play, then invariably it is too tight to come off resulting in the head pulling back through the fish and the fish being lost. The very tip has to be perfectly stable and central to maintain the straight flight of the spear. Even a very small amount of play will cause the spear to be inaccurate. This is because the extreme tip is what keeps the spear traveling true. A slight movement to one side or the other will cause a varying degree of inaccuracy depending on the amount of play. To show this you just need to sharpen a spear, which has a fixed barb, slightly off center, and you will see how much the accuracy is affected. Another problem with a drop head is the hassle. Slightly too loose and it falls off when you dive down, to tight and it stays on and pulls back out of the fish. This can be most frustrating. In terms of drag the drop head is bad, since the diameter is greater than the spear. A good head shot with a slip tip can become a major problem when it jams in the head. The only way to get it out is to cut it out. This can be difficult in the water and most frustrating when your buddy is still shooting fish around you. In terms of comparing fish lost with fixed barbs to those lost with a drop head, the majority of South African divers feel the fixed barb to be the better. In South Africa several large marlin, over 200 kg, have been landed with fixed barbed spears. Large marlin that have been lost are mostly due to the float system failing, not the spear. One of 500 kg + was lost because the diver couldn’t handle the fish in the water and eventually the boat crew "helped" by pulling on the float which parted company with the rest of the gear at an old boingie. Another disadvantage is costs; a fixed barb spear is much less a spear with a drop head.
   
• Can a railgun be loaded with the line under the spear?
  
  No. Because of the rail, anything under the spear will cause it to lift up and shoot inaccurately. When loading the gun you must make sure that the line is on top of the spear and not under it anywhere along the barrel.
   
• Will the line on top not interfere with the rubber during loading?
  
  No, it will not interfere because it moves off to one side when the rubber is loaded.
   
• What is the advantage of the clip on the muzzle where the spear line is attached?
  
  This snap clip allows the diver to unclip the spear when he is having trouble getting the spear out and push it right through the fish, line and all, before clipping it back on. Another advantage is to be able to clip a spare spear on quickly when the old spear gets damaged or lost.