Posts by popgun pete

    The bungee is for use in the shooting line if it is anchored at the muzzle, however with a reel you don't use it. Stock a lot of guns don't come with a reel, so the basic supply is for the gun using a couple of line wraps and the bungee to tension the line. This tension keeps the spear held at the open muzzle via some hooks moulded in the muzzle or via metal prongs that do the same job.

    Check out the description here

    The dividing pressure bulkhead used in the first version of the "Mirage". Left image is of the bulkhead's front face, right image is of the rear face that presses against the boss shown above. The ball valve of the pumping barrel inlet valve can be seen with its sealing "O" ring in the rear face of the bulkhead. That small "O" ring sits on the red plastic disc seen above. The small hole is the transfer port that the brass piston plug seals, if you look carefully you can see a step in it where the port diameter changes which is how Mares planned to make a lower power shot with the port not totally plugged thereby allowing air to leak past thus throttling the shot. This was not very successful in the earlier guns. The screwdriver blade slotted disc in the rear face is the screw plug for another ball valve buried in the bulkhead which faces the other way to the inlet valve. This valve only opens if the pressure differential in the gun is too high with the front tank at 40 bar plus and the rear pre-chamber at next to nothing which might then bust something, hence the ball valve here uses a much stronger biasing spring so that it only opens under very high pressure. This would only happen if you exceeded 5 strokes of the pumping barrel and had the gun at 40 bar start pressure which is its design limit.

    A better look at the front boss showing the rectangular channel at the bottom and the cut-out where air flows transversely from the air transfer port in the bulkhead which is removed here. The brass piston plug is also removed, but you can see one of the metal guide sleeves for the power regulator shaft that moves the brass piston on the right. The top holes are for locating indexing pins on the bulkhead and the other holes are to lighten the plastic moulding. The red disc is the seat for the pumping barrel inlet valve which is a ball valve built into the bulkhead that sits directly in front of this red plastic disc with the gun assembled. The pumping barrel in turn sits in front of that valve.

    I expect that you just thread the mono through one hole, whip it around the length a number of times and when you get to the bottom you run it through the other hole, so no knots as such. When the line is pulled the coils tighten up and then they stretch out taking the underlying band with it. Held tight at full stretch the mono might cut into the elastic rod, but as they are selling it I guess it works. Sort of like an inside out bungee, but there they use woven cord inside a thin rubber tube.

    How the pumping barrel operates to transfer gas in the gun from one section to another, the pumping barrel using its high compression ratio to force air into the front tank even as the gas enters the pumping barrel at ever lower pressures as it transfers from the back end of the gun with each operating stroke of the pump. This capability is conferred by the rubber sleeve valve which has a ring of exit holes very close to the rear end of the pumping barrel resulting in next to no dead space in the pumping barrel to front tank connection.

    Spearguns with closed muzzles you can wrap the shooting line last, spearguns with open muzzles you have to wrap the shooting line first as the line wraps over the spear to secure it against a pin or tab which holds the spear against the barrel at the front end of the gun. If you don’t do this then the spear can fall off the gun and the spear tail may damage the gun's sear box or the spear tail itself due to the leverage applied by the length and weight of the shaft.

    This appears to be the Velair V3 version as the run of cables involves three strands on the moving pulley block. That means if the pulley block is pulled back one centimetre by the orange cable it will move the blue cable on the diagram by 3 centimetres, so you get a 3 to 1 on the cable drive instead of 2 to 1. However the energy of the gun is dictated by the power stroke on the orange cable and in the V3 version it is reduced in length compared to the previous model, so while a 3 times multiplier seems an improvement the gun's pneumatic engine now has less energy to work with. The speed of the pneumatic drive is not a constant as it is affected by the load it has to overcome, the same with rubber bands retraction velocity as the load slows them down if you substitute heavier shafts.

    Velair V3.jpg

    velair muzzle.jpg

    As the SMG MKII has two barrels you can identify a MAGNUM version by its much longer barrels which allows the two highest power Ramset cartridges to be used. More gas pressure can then be exploited to drive the spears using longer barrels and the reinforced section of barrel is also longer.

    Just to complete the SMG story I discovered that the New Zealand company was R.V. Crockett Ltd. They produced some guns from the parts they purchased from Tapmatic Corporation in the USA. The NZ guns seem to be the MKII MAGNUM versions which can use the later more powerful Grey SUB-AMMO and Brown SUB-AMMO with their stronger breeches and longer barrels.

    You could make up your own SUB-AMMO if you purchased the SMG plastic sleeves and washers to use with .22 Ramset cartridges.

    SUB-AMMO (Instructions)
    SUB-AMMO SLEEVES are for use with .22 wadded blanks, Nos. 3 through 6, of the type used in powder actuated tools (manufactured by Ramset Speed Fasteners Company, Remington Arms, etc.)

    The blanks are loaded into the cup of the S.M.G. washer and then into the plastic Sub-Ammo sleeves.
    For a permanent, waterproof seal apply a liberal coating of clear epoxy or plastic adhesive to the cartridge just prior to insertion. This bonds the cartridge to the plastic sleeve and prevents the possibility of leakage under pressure on deep dives.

    SUB-AMMO GREEN for small fish, reef or cave shooting; SUB-AMMO YELLOW for medium fish at moderate range; SUB-AMMO RED for medium fish up to maximum range. Do not use with fibreglass spear. SUB-AMMO PURPLE for large fish at greatest ranges. Do not use with fibreglass spear.
    To protect spear head do not use near rocks.

    Maybe old age, nothing lives forever. Shell collectors sure put a lot of pressure on shell populations as everyone wants undamaged specimens and collecting them live makes achieving that aim more likely.

    Speargun manufacturers often create a style or look for their guns which they try to retain in the later models throughout the years. "Taimen” in its early days began with a spring gun which shows where the current handle design cues comes from.

    Actually over the years the trigger guard has been made much larger for just that reason. Diving in icy lake waters many Russian divers wear gloves or mittens. The last two iterations of the handle have been designed for use with gloves, the one below being the latest.

    The grip handle on a "Taimen" is larger than you think, even on the earlier "round hole" trigger finger guard frame handles I could barely get my fingers around it. Getting rid of the thumb rest ridge helped in the next model.