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All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here!

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Old 01-20-2009, 10:28 PM   #1
DynoMightDon
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Post Old GSD Italian Pneumatic Speargun




Hey guys,
I picked this gun up for ten bucks at a garage sale. I know its form the 70s and there out of business. The guns got all its parts, and a few problems. Googled the shit out of it, with no real luck. Looking for info, and repair tips. Got any?
Thanks,
Don
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Old 01-21-2009, 12:58 AM   #2
popgun pete
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Re: Old GSD Italian Pneumatic Speargun

Your gun photo is not showing for some reason. GSD spearguns use a valve operated release, once the "O" ring on the valve seat takes a set in it then the gun will no longer load and the spear comes straight out after you stop pushing on it. Unfortunately this "O" ring is trapped in a brass insert in a nylon moulding, you cannot replace it as a new "O" ring will just fall out. These parts are no longer available, so I am afraid that is it unless you have something fabricated to take the place of the original component.
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Old 01-21-2009, 04:07 PM   #3
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Re: Old GSD Italian Pneumatic Speargun

The problem with the GSD spearguns occurs during long term storage as the trigger operated firing valve seat eventually conforms to the face of the firing valve piston sitting on it all the time. When you use the gun the firing valve piston lifts off during the loading of the shaft, but it does not fall back in the exact same position when you finish loading, so air can flow back through the firing valve pushing the barrel's sliding piston and the spear back to the muzzle end of the barrel. When the "O" ring of this firing valve is in good condition it will seal regardless of this happening as the "O" ring adjusts to the piston face providing a leak proof seal, but not after it sustains a permanent deformation or set.

What I did not know was that to avoid this situation occurring the gun needs to be stored with the trigger pulled back just enough to lift the firing valve piston off the "O" ring, same idea as with scuba regulators where a plug is used to depress the arm of the diaphragm operated second stage valve and protect the valve seat from developing a similar set. This was never mentioned in the GSD gun's instructions, probably because if the gun was regularly used then this problem would not arise until the valve seat actually wore out. I had this happen to a brand new GSD Dynamic which I bought as a spare. I checked it out on land, without ever firing the gun, then put it into storage. The gun that it was intended to replace lasted longer than I thought, so when I finally retrieved the Dynamic I found that it would no longer load.

As I knew how it worked I figured that all I had to do was open it up and replace the faulty "O" ring. First sign of trouble was the "O" ring, which looked OK, would not budge, so I dug it out with an awl taking care not to scratch the metal seat that it sat in. I knew that I had a problem when I noticed the periphery of the "O" ring, which came out in chunks, had a ribbed outer edge that was tearing off as it had been trapped between the chromed brass seat's two sections, it has a front and rear face clamped together by the surrounding nylon moulding. I assume the "O" rings were installed at the factory by placing them first in the brass insert and then moulding the nylon component around it as the nylon moulding is one piece in order to make the whole assembly airtight. In their day you probably bought a replacement nylon moulding to replace the firing valve "O" ring, but unless there is a secret stash of these components hidden somewhere they are no longer available. So my GSD Dynamic, which has never been used, is permanently out of action.
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Old 01-22-2009, 09:24 AM   #4
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Re: Old GSD Italian Pneumatic Speargun

Pete,

As as always you are a wealth of spear gun information! This board is fortunate to have some one of your experience as a immediate souce of historical information

I am also not familiar with the GSD spear gun. I don't recall it being imported into the US or used in the US mainstream spear fishing community

I also cannot open the picture....do you have a picture you can post?

Hombre, keep up the good work and keep posting the valuable information...
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Old 01-22-2009, 11:31 AM   #5
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Re: Old GSD Italian Pneumatic Speargun

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Originally Posted by baja haha View Post
Pete,

As as always you are a wealth of spear gun information! This board is fortunate to have some one of your experience as a immediate souce of historical information...Hombre, keep up the good work and keep posting the valuable information...
Amen brotha WTG PopGP
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Old 01-23-2009, 03:39 PM   #6
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Re: Old GSD Italian Pneumatic Speargun

The GSD spearguns were distributed in the USA by Aqua-Craft. The guns that I am referring to are the rear handled "Dynamic" and "Katiuscia", the former had a yellow plastic component for the enveloping rear receiver which surrounded the black anodised barrel tube. On the "Katiuscia" this receiver was moulded in red-orange plastic, it also had a rear power dial for altering the gun's firing power, whereas the "Dynamic" just had a rounded rear end cap and was only single power. The lower grip handle on both guns, which fitted into the upper receiver, was moulded in black plastic and had a highly sculpted, but rather bulky appearance. Later on there was an identical looking "Pull" model with blue anodised barrel and all black receiver and grip handle; I believe this gun had a different trigger mechanism, but I have never examined one.

You can see a GSD gun on Ron Mullins' diving history web-site http://skindivinghistory.com. The guns all have a virtually identical appearance until the last gun from GSD which was the "Punto" which looked somewhat similar, but which was in reality a quite different gun. Their most notable difference being a concentric inner barrel (it was offset and mounted high up in the previous GSD spearguns) and a rear handled receiver which removed from the gun with a quarter twist and pull in a bayonet style locking action. These "Punto" spearguns had dark green anodised barrels, in fact you could buy a boxed "Punto" speargun set with 3 barrels and 3 spears of different lengths which could be swapped around on the single grip. Essentially this meant that you purchased 3 spearguns, but could only use one of them at any given time.
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Old 01-25-2009, 08:51 PM   #7
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Re: Old GSD Italian Pneumatic Speargun

Thnaks for the info. Im new to posting on this site, I tried to attach an image to my post and it said my file size is too big. so i tried to upload the picture to the my photos section of this board then copy pasted the photo url in url attachment area. which apparently didnt work, is there a better way? I have already tried the search feature for picture posting help to no avail.
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Old 01-26-2009, 12:24 PM   #8
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Re: Old GSD Italian Pneumatic Speargun

Pete,

As ever and as expected from you --- Fantastic information!

I would like to see pictures and learn more about these guns

What was the time frame--approximate year (s) the gun was marketed by Aqua Craft of San Diego?

As you know I have what is possibly the world's largest collection of dive catalogs and certainly have all the Aqua Craft catalogs from it's crude 11X 14 one page brochure by Bob Mitchell to the company's demise...so if you can provide an approximate year I would appreciate it
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Old 01-26-2009, 04:14 PM   #9
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Re: Old GSD Italian Pneumatic Speargun

Hi Sam,

Check out the Aqua-Craft 1980 "wishbook" catalogue, page 3, and you will see the GSD "Katiuscia" and the "Pull" models.

Pete
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Old 01-26-2009, 04:32 PM   #10
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Re: Old GSD Italian Pneumatic Speargun

http://www.spearboard.com/photos/sho...6&ppuser=26221 I tried it another half dozen ways, always too big, or invalid somethin or another. Best I apparently, can, or am willing to do!
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Old 01-26-2009, 05:11 PM   #11
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Re: Old GSD Italian Pneumatic Speargun

Pete,
Found them! G-31, G-49 & G-32. In my catalog they were only Id by part numbers as above,except for the G-49 which has the name 'PULL'

They were the type guns we would seldom see or use in our diving. I suspect that is why I did not recognize them by name or description

Thank you again and keep up the good work,
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Old 01-27-2009, 04:06 PM   #12
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Re: Old GSD Italian Pneumatic Speargun

I note that there is currently a GSD "Gran Gara" on eBay, the mid-handle version of the "Dynamic". There was also a mid-handle version of the gun with a rear power dial like the "Katiuscia", but it had orange trim above the grip where this one has yellow.

http://cgi.ebay.com/Vintage-Dynamic-...QQcmdZViewItem

They use the same trigger valve operating system as the rear handle version of the gun.
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Old 06-12-2013, 05:29 PM   #13
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Re: Old GSD Italian Pneumatic Speargun

I have a good gun, But I need a pump? Any Ideas?
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Old 06-12-2013, 07:02 PM   #14
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Re: Old GSD Italian Pneumatic Speargun

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Originally Posted by Dunebuggy_mn View Post
I have a good gun, But I need a pump? Any Ideas?
The hand pumps appear on eBay from time to time, that is the best way to find one, or an older dive shop may have one in an "odds and ends" box at the back of the store.
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Old 07-06-2013, 10:57 PM   #15
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Re: Old GSD Italian Pneumatic Speargun

Here is a schematic showing how the GSD "Dynamic" and "Katiuscia" releasing valve system pneumatic spearguns worked. Pulling the external trigger withdraws a stubby piston acting as a valve plug from the rear end of the inner barrel thereby allowing pressurized air to rush into the inner barrel and push the sliding piston along the inner barrel thus driving the spear out of the gun. On muzzle loading the gun the compressed air now contained in the inner barrel transfers back to the outer reservoir surrounding the inner barrel. A coil spring closes off the stubby piston valve plug as soon as you stop pushing on the spear shaft, so you can take a number of spear pushes to move the shaft right back into the gun. Only once you have squeezed virtually all the compressed air in the inner barrel back into the reservoir will the spear stay fully inserted as the tiny amount of air then remaining will, on expanding, only move the spear and the piston holding it forwards by a small amount. After that happens a partial vacuum situated inside the inner barrel between the rear end of the sliding piston and the front face of the releasing valve holds the spear and piston from falling out of the gun, with three retracting jaws located on the nylon piston nose clamped over the small ball mounted on the extreme spear tail. At the muzzle these jaws open up automatically and let the spear go, but not before as the three jaws work like a collet with a sliding sleeve holding them closed until its impact with the muzzle allows them to open up.

The stubby piston valve plug of the releasing valve system can be likened to a piston in an internal combustion engine pivoting on a connecting rod which in turn is mounted on a crankshaft. Revolve that crank through a few degrees and the valve plug either opens or closes depending on you pushing it forwards at the lower end by pulling the trigger or the rod mounted co-axial spring pushing it back the other way. Leverage built into the trigger linkages makes it easy to pull the trigger even with the gun at high pressure as you have to open the valve plug against the pressure inside the gun (the inner barrel in front of the sliding piston is exposed to ambient pressure with the gun cocked to shoot). The coil spring that closes the valve plug has no pressure differential to oppose as inner barrel and reservoir will then be at the same pressure.

If it looks complicated then bear in mind some internal detail has been left off the diagram in the interests of simplicity! The multi-power dial "Katiuscia" is very similar to the "Dynamic" seen here, but has a variable throttle valve added inside the inner barrel which restricts the air flow during the shot. This compact throttle valve is an extremely ingenious design, it takes up some space in the inner barrel where the sliding piston normally sits at the rear (therefore you lose some barrel travel due to the length of the throttle valve body) and it has very small internal parts. It took me some time to figure out how this throttle valve worked as I have never seen anything like it in a pneumatic speargun, either before or since. Modern pneumatic spearguns keep things simple and that is probably why they are still in business, unlike GSD who went the "quad cam, 12 cylinder" route in terms of the number of small parts in their guns.
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