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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 03-22-2017, 10:04 PM   #1
Fat Larry
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About roller guns..

So i've not tried a roller yet but was watching a video by adreno in australia recently where it was said that a roller allowed a diver to use a shorter gun as they're more powerful.

https://www.youtube.com/watch?v=llSylt6bXGg

Seems incorrect to me, as i understood it power came down to band configuration/stretch and barrel length only affected range??

So does a roller allow you to apply more band stretch? Are they more powerful?
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Old 03-22-2017, 11:02 PM   #2
popgun pete
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Re: About roller guns..

Yes and yes to your last two questions. Look at these diagrams for a quick explanation: https://forums.deeperblue.com/thread...agrams.107171/
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Old 03-22-2017, 11:09 PM   #3
Fat Larry
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Re: About roller guns..

Wow pete that looks like it was a lot of work. Thanks.
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Old 03-22-2017, 11:56 PM   #4
Diving Gecko
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Re: About roller guns..

And watch this too for a reality check that shows that perhaps sometimes, the theory somehow doesn't translate to practice. At least not for that particular roller kit and/or gun size:

But perhaps not all roller kits are created equal. If I recall correctly Chris Coates wrote about some tests he did and certain bearings (ceramic?) were noticeably better than others.

Last edited by Diving Gecko; 03-23-2017 at 12:14 AM.
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Old 03-24-2017, 03:00 PM   #5
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Re: About roller guns..

Of cource good designed rollerguns are more powerfull than normal band guns in equal conditions,and more accurate in my opinion and experience.They just shoot different and have more natural trajectory of the shaft.
Most of the comparing test you would see in the web are not fair becouse equal conditions means equal number of bands with equal size and equal shaft.You cant compare a roller with single 14 mm band with classic gun set with two of these bands and make conclusion that roller is weak. I didnt see here a roller with two 14 mm bands,or at least with single 20 mm band.

Last edited by seal77; 03-24-2017 at 03:08 PM.
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Old 03-24-2017, 03:47 PM   #6
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Re: About roller guns..

Quote:
Originally Posted by seal77 View Post
They just shoot different and have more natural trajectory of the shaft.

Hahaha. Now this is funny. Natural trajectory? Maybe if you're talking about a peregrine falcon dive bombing it's prey.




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Old 03-24-2017, 03:48 PM   #7
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Re: About roller guns..

Who wants a "natural trajectory"? You want the shaft to fly as flat as possible as far as possible.


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Old 03-24-2017, 05:07 PM   #8
popgun pete
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Re: About roller guns..

Those rollergun diagrams I did some years ago show the potential for energy storage in various types of spearguns. What they don't show is the energy that comes out that actually propels the spear, only what can be stored. As nothing is moved or rotated without requiring some energy to do it, and that includes overcoming any hydrodynamic drag on the moving objects, a rollergun will be less efficient than a simple "plain vanilla" speargun. However the effectiveness may be greater, which is a different aspect and is not to be confused with efficiency. Too many extra moving parts and band pulley demultiplication systems impose an energy cost which may negate some of the energy storage increase for a weapon of that size. Besides efficiency and effectiveness there is also reliability and my suspicion is that the latter has seen the rollergun disappear many times before in the past.

Once the spear is flying the launch device used is irrelevant except for the paying out and retention of the shooting line until that function is assigned elsewhere, such as with a breakaway rig.
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Old 03-24-2017, 06:00 PM   #9
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Re: About roller guns..

Quote:
Originally Posted by popgun pete View Post
Those rollergun diagrams I did some years ago show the potential for energy storage in various types of spearguns. What they don't show is the energy that comes out that actually propels the spear, only what can be stored. As nothing is moved or rotated without requiring some energy to do it, and that includes overcoming any hydrodynamic drag on the moving objects, a rollergun will be less efficient than a simple "plain vanilla" speargun. However the effectiveness may be greater, which is a different aspect and is not to be confused with efficiency. Too many extra moving parts and band pulley demultiplication systems impose an energy cost which may negate some of the energy storage increase for a weapon of that size. Besides efficiency and effectiveness there is also reliability and my suspicion is that the latter has seen the rollergun disappear many times before in the past.

Once the spear is flying the launch device used is irrelevant except for the paying out and retention of the shooting line until that function is assigned elsewhere, such as with a breakaway rig.
Pursing right goal "effectively" corresponds to throwing a spear as far as possible and as flat as possible. Saving resources in "doing that right" or "efficiently" will stand for less parts, rubber, lower cost to maintain, etc.

There should be a common denominator, a sweet spot or equilibrium, where in pursuit to ultimate effectiveness, the gun should remain relatively efficient. Might be a shaft TV or simply $.

In practical ocean spearfishing, when we are hunting in blue water, many of us are completely unused to the water clarity. We often misjudge how far away the fish is in the open water. So practical advice is to shoot fish within a range of say 6m when you can clearly see the fish eye and all the scars.

Another practical advice being an effective hunter is to conserve oxygen, to dive deeper and stay longer. That's is achieved by using the lightest tackle possible, with less parts, and concerns about the whole system performance.
You think about reel line trapped under roller rubbers - bang you loose 10sec of bottom time, you worry about muzzle rap, another 10sec of bottom time gone..
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Old 03-24-2017, 06:31 PM   #10
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Re: About roller guns..

There is actually a technical measurement of speargun efficiency that evaluates the energy stored by virtue of the loading effort compared with the velocity of the shaft leaving the gun. The Russians, with a poor choice from the few factory production guns that were available to them many years ago, and with time on their hands during the long and freezing winters, put in a lot of effort in designing and evaluating every aspect in speargun design and construction by shooting them. A gadget called a "chronoscope" was used as well as other devices to gauge shaft velocity in a swimming pool. Guns are still being developed and argued about on their forums, it seems a never ending subject of debate. Many guns were made by specialist gunsmiths, there is a long tradition of doing that there , but now production guns are emerging from modern free enterprise companies that are as good as those from anywhere.

Some guns that seem impressive don't always deliver when shots are put through them, but that does not mean that they are useless for spearfishing. For example the most inefficient spearguns were the old coil spring powered spearguns, but in their day a lot of fish were shot with them provided the fish was still there when the shaft arrived.

An old thread, but you can read about speargun efficiency here: https://forums.deeperblue.com/thread...hooting.84856/
Attached Files
File Type: doc Efficiency of guns for underwater shooting.doc (38.5 KB, 52 views)

Last edited by popgun pete; 03-25-2017 at 04:26 PM. Reason: have added the translation in an attachment
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Old 03-24-2017, 11:50 PM   #11
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Re: About roller guns..

Quote:
Originally Posted by seal77 View Post
Of cource good designed rollerguns are more powerfull than normal band guns in equal conditions,and more accurate in my opinion and experience.They just shoot different and have more natural trajectory of the shaft.
Most of the comparing test you would see in the web are not fair becouse equal conditions means equal number of bands with equal size and equal shaft.You cant compare a roller with single 14 mm band with classic gun set with two of these bands and make conclusion that roller is weak. I didnt see here a roller with two 14 mm bands,or at least with single 20 mm band.
It's something I ponder myself - what is a fair comparison? I, personally, think we should compare more on the basis of bulk, spear length and loading time/effort. If a single roller is a multistage one with a lot of prestretch, it might still take as long to load as two 14mm rubbers. Also, a double roller may or may not be more bulky than a similar double rubbered one.
Soon, I will hopefully start comparing air to rubber guns and I think it is actually fair to compare equal spear lengths. Unless, the airgun is a lot more bulky and has much less maneuverablilty.
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Old 03-25-2017, 12:27 AM   #12
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Re: About roller guns..

Band per band , a roller will spank a normal gun for the same leinth
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Old 03-25-2017, 01:14 AM   #13
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Re: About roller guns..

[quote=jstiver09;2136674]Who wants a "natural trajectory"? You want the shaft to fly as flat as possible as far as possible.

-NATURAL TRAJECTORY means that the bullet follows its way with less possible side effects.Like the rifle bullet the shaft has always less or more parabolic trajectory.There is no flat shooting. There are just different ways of aiming and styles of shooting.
-Rollers and classic band guns transfer energy to the shaft different way.This interacts verry much with the position of the flopper. This is after we have eliminated the muzzle flip of cource.
-Rollers are less dependant on the position of the flopper and has MORE NATURAL trajectory.Its obvious on the slowmotion videos that everybody can watch.There was a verry good detailed slowmotion testing of 100 guns from VIDEOCEAN and they are quite old,but people forget fast.Instead you are making fast and unfair conclusions based on the way that one man is dealing with spearguns,completely unscientific.These guys from Videocean never made conclusion like 'this gun is top' or 'this gun is shit',althought they are the only that have this right so far.
-With the same confidence that some people say rollers are low shooters,I can say that most classic band guns with open track and down flooper shafts has TWISTED and NOT FLAT trajectory with lifted tip.And they shoot too high,over stright line of the shaft guide at closer ranges arrownd 3-4 meters,the most used range in the spearfishing generally.I have missed a lot of fish in my younger ages before I adapt to this.People with real spearfishing experience and thinking will understand what I mean.Of cource this effect compensates the drop at 6 meters,but this still doesnt mean FLAT!
As you are verry competent and have so big experience please explain us this interaction that Im talking aboutI will make it easyer for you with these two screenshots.
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Last edited by seal77; 03-25-2017 at 02:59 AM.
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Old 03-25-2017, 03:04 AM   #14
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About roller guns..

Seal, I have released video along with many others showing data that completely contradicts what you say. Majd and Peterislame both posted video of your roller shooting, and the results were less than impressive. In fact, the only roller gun I have seen in video and used personally that I thought looked good was the Alemanni. But Vamforce nailed it above, it gets to a point that guns become too complicated and unpractical. Please watch my videos of the Abellan Albacore 130 and Majds as well. Now please show me a roller gun that clearly outperforms that gun. If you do, I will buy it.


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Last edited by jstiver09; 03-25-2017 at 03:12 AM.
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Old 03-25-2017, 04:19 AM   #15
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Re: About roller guns..

Quote:
Originally Posted by Diving Gecko View Post
It's something I ponder myself - what is a fair comparison? I, personally, think we should compare more on the basis of bulk, spear length and loading time/effort. If a single roller is a multistage one with a lot of prestretch, it might still take as long to load as two 14mm rubbers. Also, a double roller may or may not be more bulky than a similar double rubbered one.
Soon, I will hopefully start comparing air to rubber guns and I think it is actually fair to compare equal spear lengths. Unless, the airgun is a lot more bulky and has much less maneuverablilty.
As you see spearguns are developing verry fast last couple of years.Good designed roller system doesnt need multistage loading even with high prestrech.
How bulky and how long a gun must be depends on the maximum lenght and diameter/weight of the shafts variety it is designed to use. So you can compare difference in performance of a pipegun and a heavy multi roller with equal,lets say 7 mm shaft,but you cant blame the roller is more bulky,becouse its designed to float with 9 mm shaft for exemple.
So far I havent seen a really fair comparing test,and this is what Im planing to do as soon as a collect enough guns.
From left to right-maximum diameter of shaft in mm: 8/7.5/7.5/8/8/8.5/10mm
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Last edited by seal77; 03-25-2017 at 04:36 AM.
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