Bluewater Pneumatics - Pros and Limitations

[popgun pete]

A series of ring or doughnut type floats could be added to the barrel to counter its weight when loaded, that is what the red circled items are. The Hydra was supplied with both short and long barrels with spears to match in the "Hydra Sprint" version. With the gun mostly full of water except the rubber bladder in the rear they are very heavy guns.

 

[Gazz]

I think in the world of bluewater and "high stakes" fishing you want your gear to be as reliable as possible. I think the simple version of modern pneumatic spearguns like the predathor which are tough (glass filed nylon), powerful and simple are the best way forward. When operating at crazy high pressures things tend to break, I have never had any failures that i can recall from my salvimar pneumatics, aside from the vacuum gaskets.

I am wondering at what point does terminal velocity occur? At what point will the gun be over powered and loose accuracy?
I remember reading the Asso 115s with the tovarich kit and 130cm 7mm spear was performing optimally at 24BAR (any more and things breaks and recoil or jump can affect the accuracy), I know I have used an Asso 115 in standard form and found their accuracy to be jeopardised at high pressure.

I can fit a 9mm spear on the salvimars but vacuum Sealing this sized spear becomes a issue, has anyone tried the 9mm spear? I am also wondering about recoil.

Pete my Predathor vuoto 130 (power reducer removed and with 1000pumps(maybe 20BAR?)) is a absolute weapon against kingfish, i have shot 3 in one shot before and the gun has been entirely reliable. This is why i think they have real blue water potential. i would be keen to get my hands on a 150cm version.

I am keen to do some more blue water hunting and be able to record a pneumo getting the job done.

 

[popgun pete]

You can convert any gun if you can source a longer inner barrel tube and tank tube, which is what Mares did to make their longer “Pippin” models of the "Sten" which went up to 150 cm. There were three different Pippin gun lengths, all greater than 100 cm, but they were not widely distributed and I remember some of them being sold off on eBay, brand new! They were relatively expensive, but prospective owners had to think about loading them and that affected the demand. The actual parts manufacturer brings in stock lengths of alloy tubing for both barrels and tanks and then cuts them off to the desired lengths for different models and has them machined and anodized. This machining and anodizing is probably done by a sub-contractor and the tubing itself will come from a metal extrusion plant making stock size tubes. Find the source of the alloy tubing and you can get someone to machine it to the required dimensions.

The alloy barrel tube for the Sten has been around since 1967 and there must have been tons of that tubing made, and most likely all Italian pneumatic guns use the same stuff for their 13 mm inner barrel models. Ditto for the 40 mm tank tubing. There may now be another supplier in China, but of the exact same alloy who knows?

 

[popgun pete]

Just had a quick check of alloy tubing. https://www.ebay.co.uk/itm/ALUMINIU...60:m:m0VUPkSlVaEa28jw1I42T2g&var=493045007858

The problem is you need the correct alloy and the correct heat treatment that gives it its strength. When I tried buying materials to build a hydropneumatic gun I found tubing about the right sizes, but telling the sales guy what the application was he said if you use this stuff it will explode because a lot of aluminium extrusions are for architectural purposes such as handrail or decorative columns and are too weak for the job. So finding the correct tubing is vital. I ended up buying a gun rather than building one and that is how I met Sergey Kravchenko.

 

[tromic]

Just had a quick check of alloy tubing. https://www.ebay.co.uk/itm/ALUMINIU...60:m:m0VUPkSlVaEa28jw1I42T2g&var=493045007858

The problem is you need the correct alloy and the correct heat treatment that gives it its strength. When I tried buying materials to build a hydropneumatic gun I found tubing about the right sizes, but telling the sales guy what the application was he said if you use this stuff it will explode because a lot of aluminium extrusions are for architectural purposes such as handrail or decorative columns and are too weak for the job. So finding the correct tubing is vital. I ended up buying a gun rather than building one and that is how I met Sergey Kravchenko.

Look at this site: https://pescasubapnea.forumfree.it/?t=77464535
It seems that with Salvimar piston might be some corrosion issues..?
Maybe salt water can past by the piston easier than with Mares piston..

 

[Vlanik]

[QUOTE = "tromic, post: 992642, member: 13775"]
Посмотрите на этом сайте: https://pescasubapnea.forumfree.it/?t=77464535
Кажется, что с поршнем Salvimar могут быть некоторые проблемы с коррозией ..?
Возможно, соленая вода может пройти мимо поршня легче, чем с поршнем Mares.
[/ QUOTE]
Все поршневые ружья пьют воду...

 

[popgun pete]

Most likely a vacuum barrel gun has been leaking and letting water enter the inner barrel after the gun is cocked. During the shot the piston drives water along the inner barrel which squeezes past the temporarily blown open vacuum nozzle, but not fast enough and a hydrostatic pressure spike in the barrel blows the rubber seal on the piston rearwards in its seating groove allowing water to enter the gun across the pressure boundary. Saltwater inside the gun gobbles up the sear lever and any parts on the piston made of steel if left for long periods in the gun, especially if there is next to no oil in the gun.

 

[Gazz]

Look at this site: https://pescasubapnea.forumfree.it/?t=77464535
It seems that with Salvimar piston might be some corrosion issues..?
Maybe salt water can past by the piston easier than with Mares piston..

Its true, one of my salvimar guns that sat around for a long time ended up corroding on the piston.

 

[Gazz]

Most likely a vacuum barrel gun has been leaking and letting water enter the inner barrel after the gun is cocked. During the shot the piston drives water along the inner barrel which squeezes past the temporarily blown open vacuum nozzle, but not fast enough and a hydrostatic pressure spike in the barrel blows the rubber seal on the piston rearwards in its seating groove allowing water to enter the gun across the pressure boundary. Saltwater inside the gun gobbles up the sear lever and any parts on the piston made of steel if left for long periods in the gun, especially if there is next to no oil in the gun.

Hi Pete, how has the performance of the Black sea been? Have you used it for

Just had a quick check of alloy tubing. https://www.ebay.co.uk/itm/ALUMINIU...60:m:m0VUPkSlVaEa28jw1I42T2g&var=493045007858

. So finding the correct tubing is vital. I ended up buying a gun rather than building one and that is how I met Sergey Kravchenko.

How has the Black sea speargun been? Have you used it for any Bluewater diving, do you know any performance figures?

 

[popgun pete]

The "Black Sea" hydropumping hydropneumatic is a powerful shooter, much like a souped-up pneumatic to aim and shoot, but until one is made to float after the shot it is not so useful in deep water as drop it and you may never see it again. Unless you can hand it off to someone while despatching your victim it becomes a liability, whereas my other powerful guns can just be cast aside and will head for the surface where they look after themselves. My thoughts are the real application for these guns is scuba spearfishing which of course is now prohibited in many places. In recent years my “Black Sea” gun has not fired a shot, too much steel and titanium to be a floater, the price for the gun holding its pressure without blowing to pieces.

 

[popgun pete]

Salvimar, who used to be Salvis and FIgli, made metal gun components for other companies' pneumatic spearguns and they may be worth writing to and asking where they get their barrel tubes from. For sure it is a specialist metal extrusion plant in Italy and it will make a range of tubing products.

Alloy tubes sources, you want seamless precision bore high pressure tubes (not pipe, tube has tighter tolerances). https://www.simposiodeilambruschi.it/32151/honed-aluminum-tubing-retailer-iran/

Seamless Aluminum Tubing | Hydro Extrusion North America

Hydro Extrusion is a leader in seamless aluminum tubing, structural aluminum tubing, and standard and custom aluminum extrusions. Contact Hydro Extrusion for more information on seamless aluminum tubing in all shapes and sizes.

www.hydro.com

 

[Diving Gecko]

I remember Dima kept referring to italian barrels as “Duralumin. So, I looked it up and it’s an old trade name for 2000 series alu, perhaps 2024, which when tempered is quite hard so it could fit the bill. On the other hand it was mentioned that it doesn’t have much corrosion resistance so that doesn’t jive with our barrels.
Maybe it’s just good old 7075-T6 or could be some 5083 (I think that’s the common marine grade). But though I’ve tried for a long time to find out I am still no closer.
If Salvi don’t want to share, there must be someone in one of the Italian forums who knows. Perhaps not where the barrels are made but at least which alloy and temper it is.


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[popgun pete]

Found this: Aluminium alloys commonly used in the marine industry include:

• Aluminium-magnesium alloys - 5000 series, used primarily for rolled materials (sheet/plate). Most common are 5083 & 5383.
• Aluminium-magnesium-silicon alloys - 6000 series, used primarily for extruded sections. Most common are 6082, 6061, 6005A & 6060.

Applications for 6061-T6 Aluminum

Aluminum in its purest form is too soft and reactive to be of structural use. However, its alloys, such as 6061-T6 alloy, make it structurally stronger and more useful in the manufacturing of durable products.

6061-T6 aluminum properties make it a material of choice for builders of boats and watercraft because it’s strong and lightweight. It is ideal for sailboat masts and for hulls of larger yachts that cannot be made from fiberglass. Small, flat-bottom canoes are almost entirely fabricated from 6061-T6, although the bare aluminum is often coated with protective epoxy to improve its resistance to corrosion.

Other common applications of 6061-T6 aluminum include bicycle frames, applications where heat transfer is required, such as heat exchangers, air coolers and heat-sinks, and applications where 6061-T6’s non-corrosive characteristics are important, such as water, air and hydraulic piping and tubing.

Aluminum 6061-T6 alloy conducts and dissipates heat well. Since it can be extruded, it can be formed into almost any imaginable shape. With our advanced processing and heat-treating equipment, Hydro has developed an improved machinability 6061 formulation used in the ECON-O-ROD®, ECON-O-HEX®, ACC-U-ROD®, ECON-O-PLATE®, ACC-U-BAR™ and ACC-U-PLATE® products, which conforms to industry specifications.

 

[Diving Gecko]

The 6061 I’ve cut for Mirage pumping barrels is quite easy to cut but then again it’s probably untempered or a lower temper. With a good temper and anodizing perhaps it’s good enough for barrels.
Anodizing is a small rabbit hole on its own and you can actually get a deeper and harder “hard anodizing” done but iirc it tends to become dark grey which is what led me to assume our barrels are not hard anodized. But maybe you can hard anodize and still keep it from going dark. When you cut salvi’s barrels they definitely have a bit of a hard crust to them.

I have an underwater camera housing made from tempered 5083 and then hard anodized (and coated) and the surface on that is very, very hard and scratch resistant. Some day, I’ll have to do some mods on it which involves milling and drilling but that’s way in the future. But will be interesting to cut it.


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[popgun pete]

I have a photo of poor quality. These are guns of the master from Crimea krim4ak
Andrzhievsky Oleg. I held these guns in my hands. And this is a very high class of manufacture. This is not hydro pneumatics. These are pneumatic guns in which the piston is pushed into the gun with water. Made of titanium.
For such a system, Pete's conclusions are correct that they can be dangerous during charging. I myself have witnessed an accidental shot and a finger injury.

I thought that this gun looked familiar as I had seen it before and have now found it again on Hanter's site. One interesting aspect which does not detract from the danger in inserting the spear into an already charged gun is that the piston is in two parts. When you push the piston back in what is essentially a standard pneumatic by injecting water with the pump only the rear half of the piston latches on the sear lever. The front half of the piston stays at the muzzle. You open a valve that allows water to be pushed from the barrel as the front section of piston is pushed back with the spear and re-joins the rear piston section at the back end of the gun. The diagram shows the basic principle, but not all the details. A ring of small 0.5 mm holes in the barrel allows water out, but is traversed by the piston seals during a shot which can lead to nibbling of the periphery of the seals.

 

[Diving Gecko]

Just a quick note on the idea of using the stock pump for "hydro loading": I think it would still make a whole lot of sense to make a new pump. Whilst I don;'t have a Salvi pump here, all my other pumps have rods made from non-stainless steel. Maybe it's galvanized but it pits and corrodes and does so fairly fast.

Also, personally, I wouldn't mind having to increase the number of strokes for a shorter pump with a smaller ID to make storing the pump and the loading effort easier.

 

[popgun pete]

It may be possible to construct a gun like a Mirage, but with the pumping barrel being operated by pushing water down it instead of a spear. That would allow the pump to be placed at the rear and along the side of the gun, same as the pump loading gun made by Andrzhievsky Oleg. This would leave muzzle loading of the spear into a largely depressurised main barrel with the bulk of the loading effort being applied at the rear end of the gun. At the completion of each pumping barrel stroke a tap would be opened to let the water out and then closed for the next round of pumping.

 

[ECK]

Just a quick note on the idea of using the stock pump for "hydro loading": I think it would still make a whole lot of sense to make a new pump. Whilst I don;'t have a Salvi pump here, all my other pumps have rods made from non-stainless steel. Maybe it's galvanized but it pits and corrodes and does so fairly fast.

Also, personally, I wouldn't mind having to increase the number of strokes for a shorter pump with a smaller ID to make storing the pump and the loading effort easier.

What power should Spear have?
Does your experience have a choice of this power?
I see that using a pump is a simple solution. But this is a lot of fuss and not very convenient.
Maybe you need to look at FZSM?

 

[ECK]

It may be possible to construct a gun like a Mirage, but with the pumping barrel being operated by pushing water down it instead of a spear. That would allow the pump to be placed at the rear and along the side of the gun, same as the pump loading gun made by Andrzhievsky Oleg. This would leave muzzle loading of the spear into a largely depressurised main barrel with the bulk of the loading effort being applied at the rear end of the gun. At the completion of each pumping barrel stroke a tap would be opened to let the water out and then closed for the next round of pumping.

This can be done, but the new design is likely to have its own diseases. But can it be easier on Oleg’s design to use a safe loading algorithm? The idea is good!
Almost unlimited power, fast charging ...

 

[Diving Gecko]

What power should Spear have?
Does your experience have a choice of this power?
I see that using a pump is a simple solution. But this is a lot of fuss and not very convenient.
Maybe you need to look at FZSM?

I have some very specific requirements. E.g. all my guns are very close to neutral in the water when loaded and have handles modified to allow me to grip them as high as possible and more in line for increased recoil control. So, a sinking gun with an old school handle is not for me.

I’ll probably build a gun in the next year or so from scratch to fill my needs and push the handle placement even higher and slimming down the gun profile for easier tracking plus a few more tricks;-). As for loading it, I may use a lever type sur-compressor pump built into it or something else. Not entirely sure yet - which is why I like this thread for showing me another option.

As for power, I need at least 50kgf on the piston when loaded. That’s what I feel is needed to really power up 8-9mm shafts. I can only load max 30kgf on a traditional gun hence why I need a Mirage type loading mechanism, a hydro pump or a pulley or easy loader for my BW gun.


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