Rob Allen 110cm roller railgun: alloy v. carbon, notch/sharkfins/pin, slip barb v. regular RA barb? | DeeperBlue.com Forums
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Rob Allen 110cm roller railgun: alloy v. carbon, notch/sharkfins/pin, slip barb v. regular RA barb?

Mr. X

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The South African (ZA) style railguns don't seem to fit our current categories well. Esp. as they seem to be made primarily in ZA and Taiwan and sold in Africa, Australia, NZ, USA and, to some extent, all around the world. So I've post this thread at a higher level.

I recently watched a short YouTube video by Rob Allen, comparing recoil at the muzzle for their alloy barrel vs. their carbon barrel. It looked like one - presumably the lighter carbon barrel - kicked up vertically more while the other mainly kicked back horizontally, with very little vertical movement. I watched it on TV, so if there was explanatory text, I couldn't see it. I wondered if anyone would care to elaborate on the possible implications of this?

For example, which type of recoil/barrel would benefit most from the recoil reducing properties of a roller muzzle? Would a carbon barreled RA rollergun be more or less accurate than an otherwise identical alloy rollergun?
 

Mr. X

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While we are on the subject Rob Allen rollerguns, I think they come with a notched spear by default. Any thoughts on using a sharkfin or pin finned spear instead? I've been keen to try sharkfins but, as I learn more about them, I've cooled to the idea. I'd also be inclined to stick with or near the factory configuration for Rob Allen as they seem to put considerable effort into getting this right.
 
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Mr. X

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Finally(?), I've seen a few spearos on YouTube using the RA rollergun but none using it with the RA drop flopper. A 110cm RA roller railgun equipped with the RA drop flopper spear seems like it should be a formidable combination, capable of spearing almost any large fish and under a wide variety of conditions. Any thoughts on why that might be? E.g. cost, time to reload, accuracy, balance, mass, complexity, etc.

It occurs to me that a normal RA flopper is quite big, strong and effective - mine came properly tuned from the factory and never needed adjustment, unlike other spearguns I've owned. So perhaps most purchasers just don't need a drop flopper spear, or perhaps don't need one enough?

Or is this simply another case of: there is no single speargun that can do it all (well)?
 
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Rob Allen

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Regarding the recoil video, it has an explanation below the video explaining it. The ali recoiled backwards and upwards. The carbon, only backwards. This upward movement with the ali, causes the spear to be knocked on the way out causing the spear to develop a small wobble. This induces drag and slows the spear down more that with the carbon.

Regarding rollers, the recoil is way less so, very little difference if any between the carbon and ali other than weight. The problem with most rollers is the weight of the roller. The shorter (1m and less) ali rollers are not buoyant enough to float without the spear due to the added weight of the roller, the carbon helps with this but again, the short ones (0.9m and less) are not buoyant without the spear. When we fit roller muzzles to a carbon, we do not include a muzzle weight as the roller mass is sufficient.

The only way around this buoyancy issue is to use a cuttlefish barrel. We are working on these.

Regarding pinned or notched, all work fine on our rollers.

Regarding the drop barb spear on roller guns, they work fine but… you need to make sure the trailing toggle line is correctly trapped in the O ring. If not, it can hook up on the roller and cause the shot to miss. These do take longer to set up but, when hunting trophy fish it should not be a factor. The holdability of the drop barb is way better than a standard barbed spear.
 

Mr. X

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Thank you Rob. :)I hoped you'd find this thread. Awesome response. :)A complete set of answers to all my questions!

The 110cm RA carbon roller railgun sounds like an incredibly versatile choice, when visability is good and/or the fish are large.

BTW Surprised that the non-roller carbon barrel kicked up less than the aluminium barrel. Is that because you weight the muzzles of carbon barrels?
 

Rob Allen

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Correct. The lead piece in the muzzle means that the mass has moved a long way forward, dampening the barrels ability to rotate during the recoil, keeping the spear as straight as possible, increasing spear speed. Result is better penetration.
 

Hugo63

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On this subject, I had a RA roller 110 bought in SA (Ali) and it does not float at all. It sinks when not loaded. Is that normal ? The shop said there were no water in , and to try to insert some foam in the barrel. Is that easy to do this? It seems there are a few guys saying the same thing. I sold it to a friend that dives with me and he does not use it because of that. With a fish in a cave you can’t let the gun go or it will sink and you won’t find it.
Any explanation ? It was bought in the first year of production of this gun
 

Rob Allen

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It might have a lead piece in the muzzle, some of the earlier ones went out like that. Please check.
 
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IYY

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Hi! When you say the 900 roller is not buoyant, do you mean the carbon one as well? How is it balanced? Cheers
 

Mr. X

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Hi! When you say the 900 roller is not buoyant, do you mean the carbon one as well? How is it balanced? Cheers
I think Rob already answered that: "The shorter (1m and less) ali rollers are not buoyant enough to float without the spear due to the added weight of the roller, the carbon helps with this but again, the short ones (0.9m and less) are not buoyant without the spear." i.e. Yes. Re. balance, I don't know but suspect a little muzzle heavy, as most/all of my speargun have been.

Will there be an inverted Rob Allen roller speargun in the future I wonder? Hmm. The cuttlefish barrel sounds intriguing - carbon/PU sleeve? Hmm
 

Rob Allen

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