Mares Bazooka 140 cm

What a beast, bazooka is very appropriate. Look at the thumb rest on the handle, that must have been advanced for its time. 3 power levels :@ the gun must need them.

I always thought they could come up with a heavy duty pneumatic for big tuna instead of luggin a tree down with you. The technology is not quite safely there yet.

Nice pneumatic, that handle looks a long way from the back of the gun. Doesn't it feel akward holding or shooting it?

BTW there's one on ebay right now. Item # 350 446 522 322 in case someone is interested.

Quote from greekdiver

I always thought they could come up with a heavy duty pneumatic for big tuna instead of luggin a tree down with you. The technology is not quite safely there yet.

Sorry for bringing a very old thread to life and hijacking it, too. But I just read this and thought of a gun in development by a Ukranian spearo and gun maker. He is a mad genius and I mean that with the outmost respect:-)
The goal is to make a powerful pneumatic tuna gun which handles much better than the big logs of wood and is as or more powerful. I think he is aiming at a muzzle speed (?) of about 50 m/sec - which is a lot!

It's a hydro-pneumatic, so you use sea water pumped into the gun during loading to pressurize it.
I think in its current state it shoots a 9mm shaft.
It's a titanium gun with a stainless steel barrel and a wood stock for buoyancy.

Me on the left with the tuna gun and Dima, the inventor on the right with a smaller vac-muzzled traditional gun:

Quote from Don Paul

Don't worry about reviving a old buried thread...I love continuing knowledge.:thumbsup2:
Yeah the Ukrainian gun is cool, some smart guys there.....with big piles of Ti and brains.

Cheers, Don

More info on the tuna gun here:
Самое мощное безраÑходное подводное ружье

Actually, his whole site is pretty cool. Some is English, a lot in Russian, but you'll get the gist of things via google translate.

And Dima just looooves shooting his guns above water and lodging shafts deep into logs of wood... haha

I have a vac muzzle, piston and Ti sliders on my way from him. I'll probably write a post when they get here:)

These Aquatech guns are probably the inspiration for this new hydropneumatic lever pumped gun, but for some reason the guns are no longer available as the Aquatech website is no longer maintained. The lever pumped guns are the top two on the upper right of the composite model image.

Quote from Diving gecko

I think he is aiming at a muzzle speed (?) of about 50 m/sec

Seriously? He anticipates being able to get the shaft to fly 50m/sec? That's almost twice the speed we can get now. That would be something to see. I think the biggest obstacle would be stability. If he can get the shaft out at that speed and keep it stable then he will be accomplishing some great things.

Quote from Silentstoning

Seriously? He anticipates being able to get the shaft to fly 50m/sec? That's almost twice the speed we can get now. That would be something to see. I think the biggest obstacle would be stability. If he can get the shaft out at that speed and keep it stable then he will be accomplishing some great things.

During initial testing of the Aquatech "Black Sea" gun a spear of 9 mm diameter was measured exiting the gun at 45 m/sec. Some of the gun testing articles are still on the Web, but not the speed measurements as far as I can tell.

AQUATECH Speargun

I remember that muzzle velocities attained were certainly over 40 m/sec. and mainly around 43 m/sec. In order to make any gains at these high velocities gun power needs ever larger increases for each extra increment, hence it is a case of diminishing returns as drag increases rapidly as the shaft has to virtually tear a hole through the water. Once that cavitation sheath collapses then the shaft experiences surface drag which soon pulls the speed back. Once it is flying the trailing shooting line stabilizes the shaft.

Quote from popgun pete

During initial testing of the Aquatech "Black Sea" gun a spear of 9 mm diameter was measured exiting the gun at 45 m/sec. Some of the gun testing articles are still on the Web, but not the speed measurements as far as I can tell.

AQUATECH Speargun

I remember that muzzle velocities attained were certainly over 40 m/sec. and mainly around 43 m/sec. In order to make any gains at these high velocities gun power needs ever larger increases for each extra increment, hence it is a case of diminishing returns as drag increases rapidly as the shaft has to virtually tear a hole through the water. Once that cavitation sheath collapses then the shaft experiences surface drag which soon pulls the speed back. Once it is flying the trailing shooting line stabilizes the shaft.

That is nuts. So if that speed has been reached why is that not our norm? Our average (band guns) do what, 30 m/sec?

Quote from Silentstoning

That is nuts. So if that speed has been reached why is that not our norm? Our average (band guns) do what, 30 m/sec?

Band guns are easy to use, don't require much maintenance and are rugged enough to take a certain amount of abuse when used by owners who are not overly careful with their underwater weapons. Pneumatic guns and their hydropneumatic cousins are not so forgiving, but it also depends on the individual gun. The "Bazooka" featured in this thread has thick metal wall tanks and is built to take some knocks, whereas some pneumatic guns, like most of the rear handle models, have thinner wall tanks which can dent.

Band guns are less efficient, they would need more energy stored in their band battery to equal the velocities achieved by pneumatic powered guns. But as fish have been successfully hunted without recourse to such high shaft velocities band guns have remained with a lower, yet adequate performance which is all that is required for the job. Band by band loading where each wishbone draw is exactly the same is where the band gun has an edge on the pneumatic powered weapons and with enough band power a band gun could equal pneumatic and hydropneumatic gun performance, however the gun would be more bulky due to the space on the gun required to mount the band battery when stretched out for full power shooting.

Yes, I agree with Pete. Pneumatics are overall just a more efficient design. Well, when we compare to traditional single banded guns and some double banded ones, at least.
But I am really hoping to finally do some proper tests on some of my airguns in a month or two on my next trip, hopefully throw a Pathos 100 in the mix, too. It would be great to finally have a better idea about how my guns shoot - I started on pneumatics and have only shot fellow spearos' band guns on occasion.

I'll try to list the reasons I consider them more efficient:

• Pneumatics have close to 100% "band stretch". Meaning, the piston will push on the shaft through the whole length of the barrel. Though, with a bit less force at the end but still with much more force than bands which go slack and do zero work for about 30% of the 'stroke'.
  

  
  

• Bands have to expand during the shoot and move forward - both carry some hydrodynamic penalties.
  

  
  

• Bands add recoil (on traditionally set up band guns). An airgun only have to move a 10g piston forward in addition to the spear plus they have a bit more mass than your regular 28mm pipe gun. So, all in all a pneumatic should have less recoil.
  

  
  

• The piston in an airgun suffers from friction, but in all likelihood much, much less so than bands moving along a gun (and through the water as mentioned above). The spear in a pneumatic has different kinds of friction acting on it vs. a rail or ET on a band gun. There's a bit where the spear glides through the muzzle and also through the slide ring for the shooting line. The biggest one could be the effort to tug loose from the friction fit of the piston as the piston stops it travel at the shock absorber at the end of the barrel - I don't know if it is a lot or a little.

Hopefully someone will some day really compare the best of recent band guns to pneumatics. There's room for improving the traditional pneumatic, too.
One thing I do wonder about is whether it is a potential issue and "energy robber" that the spear in an airgun is only suspended at the ends by the muzzle and piston - there is no rail supporting it. The spear could bulge and sink a little in the middle as it is just hanging in air (in the case of a dry barrel gun) or water in the barrel. So, during the shot, this slight banana shape will have to be straightened out on its way through the muzzle and I don't know if that can make the shaft unstable - or the opposite. A long overhang could help with this, but personally I have as little overhang as possible as I worry about the guns being nose heavy.

I am not sure, but 30m/sec sounds high for a band gun?
A ten year old pool test done by Russians (Ukranians?) showed two shorter vacuum muzzled guns to shoot at about 28m/sec. A hydro-pneumatic gun in the same test was measured at 41m/sec. The guns were all very short as they were mostly intended for river hunting.
I don't know if they are muzzle speeds or average speeds over the course of 2m as a 2m distance to target is listed, too.

Nicely put gentlemen.

Diving gecko, with respect, some of your points regarding the efficiency of pneumatics over bands I am not seeing what the true benefit is.
-Regarding the contraction of the bands in relation to hydrodynamics I do not see how this is an issue. Yes, the bands contract and are less hydrodynamic, but to what loss? Isn't the energy already sent to the shaft at that point? The contracted bands shouldn't slow the shaft down, or does it? Unless the issue you are referring to is the loose contracted bands are now not moving as easily through the water when you are swimming, but on the shot itself I do not see an issue. Is there?
-Regarding recoil, I haven't shot pneumatics, but based on what you are saying it appears that is based off 2lb pipe guns. Since you have shot both I'm sure you would know more than I do what would have more recoil, but some band guns are monster logs. Whether those guns have less recoil than a comparable pneumatic, I would not know. If you were to compare a nicely weighted wood gun to what would be an equivalent pneumatic, would the pneumatic truly have less recoil?

With regard to the 30m/sec for band guns, now that you mention it I believe you are correct that 30 is the high. I just remember hearing 30, but thinking back after you point out the Russians (Ukrainians?) I believe when I heard that it was in reference to them and that was a high. I believe average is mid 20s??? Don't quote me on that though.

But I guess, like Pete alluded to (I think), it isn't about reaching the greatest speeds. It is about obtaining the speed necessary for the purpose.

I am sure some of my points were more theoretical than a real life issue. Could be so with the band contraction. But on some level there has to be some energy loss when the bands have to move through water themselves during the shot. I was just pointing out that the "engine" of a pneumatic is internal and there is not much drag on it.
I don't know if there's a real world difference in it, though.

I actually haven't shot many band guns and yes, you are right - I was making the comparison to a pipe gun;-). It's a good question about recoil of two equally heavy guns, though. I would say that if spear has the same mass and the band gun is a regular band gun without some sort of recoil cancellation or recoil reducing setup (like a roller, inverted roller, pulley, etc) then the pneumatic should have less recoil because less mass moves during the shot. Unless of course it really shoots a whole lot faster so that recoil starts increasing.

I'm not a theoretical guru, but I've shot many band guns and pneumatic guns over my life. Now I have a chronic wirst injury and I can only use rollerguns or pneumatics to avoid pain.

I have never shot a big tuna gun, but I have shot a 110 Abellan and I can positively say that a Cyrano EVO HF has (lots) less recoil than the Abellan.

And if you compare with railguns, it's night and day.

Quote from Marco

I'm not a theoretical guru, but I've shot many band guns and pneumatic guns over my life. Now I have a chronic wirst injury and I can only use rollerguns or pneumatics to avoid pain.

I have never shot a big tuna gun, but I have shot a 110 Abellan and I can positively say that a Cyrano EVO HF has (lots) less recoil than the Abellan.

And if you compare with railguns, it's night and day.

That is because many railguns are too light, especially with carbon tube barrels, whereas a certain amount of metalwork is unavoidable in a pneumatic gun. Tuna guns that are properly ballasted don't have much recoil, but are very heavy guns out of the water and are bulky in the bodywork in order to float. Steve Alexander and Bill Kitto are the guys who have written quite a bit on gun ballasting, so something to read up on. No theories there, just the facts.

http://www.alexanderspearguns.com/
http://ic_spearguns.tripod.com/