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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 04-03-2019, 05:27 PM   #1
popgun pete
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Slingshot Weapon with pulleys

While not an underwater speargun, check out this oddball weapon that shoots a shaft. Not entirely sure why it uses such tiny bands, but it uses plenty of them! Somewhat reminiscent of Jack Prodanovich's experimental rollergun with a transverse roller system designed to create a powerful gun with one band lest future regulations saw fit to ban multi-band weapons.

https://www.hammersurvival.com/produ...gshot-crossbow
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Last edited by popgun pete; 04-03-2019 at 06:31 PM. Reason: Added a link
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Old 04-03-2019, 06:38 PM   #2
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Re: Slingshot Weapon with pulleys

Another photo which gives a few more clues as to what is going on.
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Old 04-05-2019, 03:34 PM   #3
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Re: Slingshot Weapon with pulleys

This slingshot uses a travelling front pulley system that cocks the weapon by pushing with your foot while the muzzle is pointed towards the ground. That stretches the bands out as the rear band anchors are fixed while the muzzle rollers move forward that are connected to a frame that slides on the stock. The angled handle under the gun stock is what you push on to cock the weapon and then pull back to reset for the next shot. The drive cable will, like most crossbows, be held by the trigger mechanism rather than the projectile being held as it is in a speargun.

Spearguns with travelling band anchors and foot or leg loading have been produced in the past. I remember the Technisub "Super Blitz" eurogun of the mid-eighties which arrived as a top of the line model, but in a few years was relegated to lower in the speargun pecking order. Checked one out in a dive shop, but never saw one in action. Plastic trigger mechanism and slightly flimsy looking construction may have turned potential buyers off.

https://www.worthpoint.com/worthoped...taly-170838413
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Old 04-05-2019, 05:14 PM   #4
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Re: Slingshot Weapon with pulleys

Although a rack and pawl system is needed to stop the moving carriage at any particular location when you stop pushing, it may be possible to use this leg loading method to help cock a rollergun as your legs can provide a greater mechanical advantage during pushing than your arms do while pulling. The bands travelling around rollers as the band battery stretches out would be an ideal stabilizing influence on the travelling system as band tension will be in two planes and evenly load up the carriage slider rather than just pulling on the top deck.
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Old 04-05-2019, 05:42 PM   #5
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Re: Slingshot Weapon with pulleys

Seems pretty powerful. Do you think it could be used under water, and, if so, how do you think it would work?
Can you go into a little detail about how the bands propel the bolt? Seems functionally to be a rollergun, but the way the bands propel the bolt (spear shaft?) might be quite different.
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Old 04-05-2019, 06:26 PM   #6
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Re: Slingshot Weapon with pulleys

I think too much drag for underwater use and using such skinny bands on the traverse it would thrum like a Lyre or a Harp, however there are maybe some ideas that could be used such as the travelling carriage that supports the front pulley frame. In some ways it is a rejig of the Arrow Gun which had a similar transverse roller frame at the muzzle, only the band ran right around the rear end of the gun and was under shields. I borrowed that rear band wrapping concept for the "Wiggler" cable gun and the bands never went around the muzzle rollers. On this slingshot gadget the pulleys are too big, but that is to make best use of the skinny bands which for terrestrial use are fine.

As for how it works the moving carriage cocks the bands and the bands are connected to the cable drive that propels the projectile which could be a dart or a ball bearing. The rearward set of pulleys control the cable run back to where it enters the stock and when it shoots the rearward rollers limit the forward travel of the drive cable. Being only small projectiles of low mass the drive stroke does not go right along the barrel as it appears to go only about half way. Note that the rearward set of pulleys travel with the muzzle carriage, they are all connected.

Many years ago there was a gun design that pushed the shaft with an impeller that had some mass to it and like this gun it had some extra pulleys about mid-way along the stock. The concept was the band propelled impeller pushed the shaft up to these pulleys and then the pulleys caught the bands which began to stretch as they decelerated the impeller gradually rather than the impeller crashing into a shock absorber. This made for a gun that was longer than the band drive stroke and its success can be gauged by it disappearing without any trace of its existence.

Last edited by popgun pete; 04-05-2019 at 07:00 PM.
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Old 10-13-2019, 05:07 PM   #7
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Re: Slingshot Weapon with pulleys

I have ordered one of these "cdric" rubber powered weapons to see if anything can be learned from it. This appears to be the same as the "RS-X7" version, but with a few extra parts and is coming from China at a reduced price. May be a piece of junk, but will soon find out!

Just found another version which makes me fear the worst!

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Old 10-13-2019, 10:07 PM   #8
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Re: Slingshot Weapon with pulleys

Check out this bow from China which uses rubber bands! Looks like a compound bow, but has no bow limbs that flex (which usually store the energy) and I have no idea how the pulleys work and I don't see any "let off" cams to control the pull. Looks like something from a sci-fi movie and confirms that the Chinese are big on weapons that shoots darts, arrows and ball bearings!
https://www.ebay.com.au/itm/32-KRYSI....c100005.m1851

Of course if you really want to sell something then have a cutie seen holding it.



Not unsurprisingly relisted as not too many want to stump up that kind of money, AUD 1,735 or USD 1,190, for a rubber band slingshot that looks like a bow, albeit one with "let off" on the draw.
https://www.ebay.com.au/i/183925697333?ul_noapp=true

Last edited by popgun pete; 10-21-2019 at 03:40 PM. Reason: update 10/22/2019
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Old 10-14-2019, 01:48 AM   #9
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Re: Slingshot Weapon with pulleys

This is how it works; the rubber bands in stacked sets of loops get stretched by the cams at the top and bottom and the actual cam shapes are hidden by the covering panels on the frames so that you change the leverage to adjust the draw pull to a minimum in order to hold the bow at a decreased effort until you let go of the bowstring, then the force goes up.

The rubber bands replace the bow limbs that usually act as leaf springs to store the energy when you draw the bow. Considering the size of this gadget I wonder if there is any advantage as a normal compound bow is about the same size, plus rubber bands wear out and bow limbs should not. For over a grand (at a discount) I wonder how many would be really interested in this rejigged slingshot.
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Old 10-14-2019, 11:12 AM   #10
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Re: Slingshot Weapon with pulleys

Quote:
Originally Posted by popgun pete View Post
This is how it works; the rubber bands in stacked sets of loops get stretched by the cams at the top and bottom and the actual cam shapes are hidden by the covering panels on the frames so that you change the leverage to adjust the draw pull to a minimum in order to hold the bow at a decreased effort until you let go of the bowstring, then the force goes up.

The rubber bands replace the bow limbs that usually act as leaf springs to store the energy when you draw the bow. Considering the size of this gadget I wonder if there is any advantage as a normal compound bow is about the same size, plus rubber bands wear out and bow limbs should not. For over a grand (at a discount) I wonder how many would be really interested in this rejigged slingshot.
Are there literally any advantages to this compared to a typical compound bow? I am sure if there were someone would be using these.
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Old 10-14-2019, 01:15 PM   #11
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Re: Slingshot Weapon with pulleys

That slingshot weapon looks interesting, but seems like it wouldn't shoot the projectile as fast as, say, a crossbow, or maybe I'm still confused on how it works. Update us when you get it in!

As for the bow looking weapon, I'd be interested in how that thing shoots. As powerful as it may be, consistency of power would be my concern if using rubber bands as it could stretch and crack over a short time. This would affect accuracy. But I'm going to assume this probably wasn't made for long range accuracy, competition, or big game hunting. That cable guard/slide thing has a crazy angle on it compared to compound bows.
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Old 10-14-2019, 03:05 PM   #12
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Re: Slingshot Weapon with pulleys

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Originally Posted by musubi View Post
That slingshot weapon looks interesting, but seems like it wouldn't shoot the projectile as fast as, say, a crossbow, or maybe I'm still confused on how it works. Update us when you get it in!

As for the bow looking weapon, I'd be interested in how that thing shoots. As powerful as it may be, consistency of power would be my concern if using rubber bands as it could stretch and crack over a short time. This would affect accuracy. But I'm going to assume this probably wasn't made for long range accuracy, competition, or big game hunting. That cable guard/slide thing has a crazy angle on it compared to compound bows.
The Chinese are probably whistling in the dark on this weird "KRYSIS" bow because if you search around there is absolutely nothing on it, all reference material relates back to them. This weapon is overpriced (1300 bucks) for what it is and I don't see it having much more than novelty value, the rubber bands are its "Achilles Heel". It will be powerful, but not durable, unlike a compound bow with limbs that should perform consistently over time which you could buy with less money. Bows have forward recoil with the shot, by making the limbs horizontal and opposing each other their recoil cancels out and that is why advanced bows have a tipped on their side "U" shape. This rubber powered bow has that shape, but no limbs to recoil, hence the shape is merely to look the part.

For example for 500 bucks you could buy something like this and no rubber bands to replace.

Last edited by popgun pete; 11-01-2019 at 04:43 PM.
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Old 10-14-2019, 05:44 PM   #13
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Re: Slingshot Weapon with pulleys

Almost wonder what something like that could do with actual speargun rubbers, say small ID 18mm or so, stacked on top of one another.

I was watching a Youtube series on medieval crossbow stats (https://www.youtube.com/watch?v=MMoL_SBD6gw&t=599s) and you'll see that they are loaded with a windlass system that detaches. A similar windlass and ratcheting system with proper bands could probably put a lot of power into a small package.

Not sure where the advantage lies over a more conventional crossbow, perhaps the smaller profile would have some situational advantages. Fascinating creations nonetheless although I'd refrain from trying to power up those particularly ones without fully inspecting the component parts. Best to start from scratch with quality components.
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Old 10-14-2019, 06:14 PM   #14
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Re: Slingshot Weapon with pulleys

Barnett had a "Fish Bazooka" some years ago that was band powered for shooting from the riverbank. A speargun/crossbow hybrid that seems to have since disappeared, but looked the part even though such weapons have not been welcome in some localities.

This one has been chopped down as it had a shoulder stock originally with a rear vertical strap. Note the wishbone holding trigger mech. The leaf spring holds the shaft in place. Accidently bagging someone on the other side may have been off-putting.
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Last edited by popgun pete; 10-19-2019 at 05:27 PM. Reason: added a photo of the missing butt
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Old 10-15-2019, 11:37 AM   #15
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Re: Slingshot Weapon with pulleys

I have a Sea Stinger by HeadHunter.

https://www.headhunterspearfishing.c...es/sea-stinger

I have not used it enough to get good with it. Guns are much easier. I bought it to use in the Bahamas but my Koah sling is simpler and adequate.
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