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"Kobra/Cobra" hydropneumatic speargun

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popgun pete

Well-Known Member
Jul 30, 2008
The Russian "Kobra" is a hydropneumatic speargun built using the forward latching design employed in the "RPP" pneumatic speargun, among others. The main difference is the extensive use of molded plastic parts in the mid-handle and muzzle components which were previously all-metal items, plus a much larger diameter air tank. I purchased one of these some years ago when they were being sold locally by a guy who was then importing them. The photos which I took at the time were on one of my old computer hard drives and I just found them, so here they are.
Kobra 500 1.jpg
Kobra 500 2.jpg

Kobra 500 3.jpg
Kobra 500 4.jpg
Kobra 500 5.jpg
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I purchased one of the first ones (they were sold on eBay) which were painted in basic black. Later ones had a metal flecked, glossy black finish and a slight rearrangement/redesign of the name stickers on the gun as shown here. Note the annular notches on the front end of the shafts for the forward mounted sear tooth to engage. The gun was supplied with a carry case and two spears with detachable speartips and a trident with hinged floppers, plus the usual hand pump and hand loader.
Kobra 500 Ulises photo.jpg
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The actual trigger mechanism is installed inside the plastic muzzle and is a form of pull down sear lever type found in most spring guns, only smaller in size to fit in the reduced dimensions available in the muzzle. The front pivot pin is the sear lever pivot and is alarmingly close to the outer edge of the muzzle molding! The second pivot pin is the trigger pivot, the mini trigger being operated by a pull rod that runs back to a sliding trigger in the grip handle.
Kobra 500 12.jpg

kobra diagram.jpg

Similar to the RPS-3 the gun uses a multi-drilled inner barrel tube with an outer rubber pipe covering the ported section clamped at either end. When the spear is pushed through the muzzle's "O" ring seal the water trapped inside the barrel is displaced through the tiny port holes to expand the rubber pipe radially. Air pressure inside the tank resists this expansion of the rubber pipe and provides the energy storage of the gun by causing the tank pressure to increase. When the trigger is pulled the water under pressure flows back through the port holes in the inner barrel and drives the spear from the gun. Due to the bare spear tail used the “Kobra” avoids the muzzle seal busting problems of the RPS-3, but requires a front tied spear.

No stainless steel parts appear to be used, so really a freshwater gun unless you thoroughly wash it out and pump the freshwater filled inner barrel with the spear to remove any salt residues out from under the rubber pipe where they would otherwise be trapped against the outer surface of the inner barrel.
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A few more photos to complete the set.
Kobra 500 6.jpg
Kobra 500 7.jpg
Kobra 500 8.jpg
Kobra 500 9.jpg

The gun is a non-floater and is heavy for its size, but a quiet shot is available which is important in a river or small lake where the noisy impact of a standard pneumatic piston slamming into a muzzle shock absorber may alarm all the nearby fish.
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With different internal parts this gun design is also produced as a forward latching pneumatic speargun, the "Triton". This gun is basically a larger bodied RPP. The "Kobra" muzzle has a ring of relief ports, they serve no purpose in the hydropneumatic gun, but they are necessary on this pneumatic speargun version shown in diagrammatic form below.
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As a matter of interest these two guns and another version the pneumovacuum "Barracuda" are manufactured in Chelyabinsk, the same place as the "Taimen", but the guns are worlds apart in quality and price. The main attraction of these basic guns is their affordability and durability, provided they were turned out properly.

You can see a "Kobra 600" being dismantled here: http://apox.ru/forums/topic/7361-разборкасборка-ружья-кобра-600/
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