We will put one up.

👍👍

The tests we have done show the more rubber area to stretch the better, provided you get the per-tension right.

A dark, cool location is best. I did hear UV from florescent lights can affect the rubber, I can't confirm though.

Yes, same for 14mm. We use half our barrel length + 10cm. You can always make it a little longer as you can shorten but not make it longer. Yes, 10 to 15kg for 14mm. Start out at +- 10kg, you can always shorten.

Half of 90 is 45, plus 10 = 55cm. This is a good start. At 50cm it will work if the pre-load is 25kg or less. Yes, 14mm works to the same ratio but will give slightly less pre-load. Remember the 14mm rubbers will be best for 7mm spears.

Hi Scott, the same set up (gun length and spear diameter will be better with a roller muzzle but not as big a difference when comparing a shorter gun. At about 1,3m there is not much advantage in power but there is much lower recoil. Some guys have problems with accuracy due to the recoil and a roller muzzle will help with this.

Where do you live?

RobAllenSpearfishing Miami FL

We tested up to a 130cm roller against same size guns with double rubbers. As mentioned before, the advantage was big at the shorter gun lengths but, slowly this advantage diminished. At 130 both were equal in power and accuracy when both were double wrapped. We did not test longer because we assumed it would get worse and, as you pointed out, loading would become very difficult. Our thoughts are, on the shorter guns the length of stroke with rollers when comparing was much greater. As the guns got longer, the longer guns rubber stroke lengths got better. Look at the ratio of spear ahead of the rubbers on a non roller gun compared to what is behind. The rubber has only a short stroke to power up the spear. The longer the gun, the longer that stroke ratio becomes.

Understood, thanks for the reply, and that makes sense regarding the ratio. Only asking asking because I have the 150 tuna with 7.5 mm shaft and was considering putting a roller muzzle on it. Even if I could only get equal power, it think it would be worth it for the reduced recoil.

Hello.

In pool testing, the shorter the roller the more the advantage when comparing it to a standard double 16mm gun. As the rollers get longer, the advantage in terms of power (spear penetration) accuracy, reduces. We found at 130cm, a single 16mm powered roller has the same power (spear penetration) as that of a 130cm double 16mm rubber gun with double wrap. Only advantage is that the recoil is reduced. This is why we try to recommend not going longer than a 110cm roller.

@@RobAllenSpearfishing interesting. How does a 80cm roller compare to a 80cm standard gun with 2*16mm rubbers?

@@RobAllenSpearfishing Thank you this is very interesting

@@martincjoergensen The standard gun will not be as strong as a roller in that length. Most standard guns are single wrapped with sufficient power and accuracy to the end of their single wrap. The 80cm roller will still be good to the end of the double wrap. A single can shoot 5 X the barrel length and the roller with double wrap 7 x barrel length.

It will help.

@@RobAllenSpearfishing Do you know what the weight difference is between your 90 cm rail tube in aluminium and carbon? Then I can better guestimate the effect on buoyancy.

@@martincjoergensen I can give you the barrel differences. We have a standard aluminium (1,45mm wall) A 90cm barrel will weigh 385,1 grams. The same aluminium (1mm wall, same OD) is 306,9 grams. The carbon 90cm is 266,3 grams. The carbon dimensions are exactly the same as the 1,45mm aliminium barrel.

@@RobAllenSpearfishing Perfect, thanks alot Rob 👍

There used to be wear that occurred on the wishbone line so we saw guys doubling up on these. We eventually worked out, this was due to the shooting line being pulled over the top and in front of the wishbone during the shot. Once the spear started to pull out the shooting line it would have to be dragged back around and under. You would not see this unless watched after videoing and slowing down the frame rate. We realized the problem was caused mainly due to over-powering the gun. We have since sorted this by setting the power/speed of the spear to just reach max as it exits the muzzle. This eliminates 98% of the wear. The double wishbone is a carry over from that and the general market still want it. Not a good idea to try fit both into the wishbone slot as they both will not fit. If you try, the one will go in and the 2nd will get cut/damaged on the sharp edge of the wishbone notch.

@RobAllenSpearfishing Thanks Rob. I made a band with a double uneven wishbone to try, but I'll definitely make sure I tighten up the shooting line. Just bought your 110 single roller and swapped shaft and rubber for 7mm and 14mm, for more reef shooting. Anxious to get back in the water and try it out. Only took two shots before that and they both dove low (but I did have a non tight shooting line). Thank you for your response. Aloha 🤙🏾 🤙🏾

@@cyosh345 Definitely a good idea to keep that top shooting line as tight as possible, Good luck.

It will be under powered and probably shoot low.

The reverse. The warmer the water the better the rubber works. It is easy to cut the rubbers too short and over power a gun in warm water because the warmer the rubber the better the elastic return is. So, in colder water, the rubbers perform poorly, shorter is therefore better.

@@RobAllenSpearfishing I see, thanks.

Do you have a way to gauge how much shorter a rubber should be, if it's primarily used in cold water compared to warm water? Let's say 10c vs. 25c.

@@martincjoergensen Guys in the colder areas generally cut their rubbers a good 3 to 5cm shorter than our recommend, not an exact science 😁

Thanks again. I will experiment with that. Looking forward to the next video.

Hi Pablo, I have tried an 8mm and did not like it, too heavy. I would think an 8,5mm would only make it worse.

I think close.

@@RobAllenSpearfishing awesome

Roller guns work best with a 7mm or 7,5mm spear on a rail barrel. You would be changing everything but the handle. Better to keep the Scorpia as a 2nd gun and buy a roller to what ever set up you want.

@@RobAllenSpearfishingThanks for the advice! Best regards :)

yes. You can also shorten it a little more than that if it works for you.

No, keep it the same as the spear will be lighter.

There are many possibilities. What length gun is it? What shooting line are you using? What roller did you fit? Rollers can be very tricky. The biggest problem is not tightening the shooting lines properly. If it is slack it can get sucked into the roller then get pulled out, jerking the shooting line and affecting the spear flight.

@@roballen1578 @Rob Allen my gun is 900 railgun and i bought rob allen roller kit and im using a 2mm dyneema. i have my bands at 55 cm . should i try go 1.8mm dyneema? my shootingline has tension with my bungee but ill try and make it a little more tighter

@@fidelrichardagpaoa3979 We only use 1,8mm Dyneema. Yes, try making it much tighter, especially the section from the spear line hole to the muzzle.

roballen.co.za/product/speargun-tuna-roller-railgun/

RobAllenSpearfishing oh I though it was the ex carbon GT roller.. which I purchased second hand and was wandering if there is any difference than the limited edition GT roller?

@@talsilver1815 sorry, the GT is with a carbon barrel and the Tuna is an aluminum barrel.

There is a possibility that it has moved slightly on the shaft, causing side pressure.

I have the same problem, one not spinning freely. Ive spent a lot of money on ceramic skateboard bearing over the years so I've been super cautious in taking care of these bearings, washed in fresh water after each use. Ive bought two of these because I love my 100 roller conversion and I want to do a 120 in the future. Not sure if I should take it apart or take it back to the shop....??

It all depends on your needs. Keep in mind, rollers are way more powerful and are double wrapped. A 1.1m will shoot as far as a 1,3m double rubber normal gun.

We feel a 1100 to a 1200 will be fine.

Yes you can.

We prefer to match a 7mm spear with a 14mm rubber. Try about 5kg and see how it goes.

@@RobAllenSpearfishing same calculation? Half the barrel length +10cm? I have a 80cm barrel, 14mm rubbers, 6.6mm spear and 120cm shaft

Hi Martin, We have not had great success with 6,6mm spears on rollers as they don't seem to have sufficient weight/mass to shoot to the end of double wrap line. If you are able to use a 16mm rubber with a 6,6mm spear, it could be because the water is cold. Rubbers lose its elasticity the colder the water is.

@@RobAllenSpearfishing Thanks for answering so quickly! Very interesting - the water temps have been around 14-18C, I suspect this qualifies as "cold" compared to South Africa ;) Clearly there is lots to be learned - this begs for more videoes on the subject. I hope you will do an in-depth video(s) explaining pros and cons of different setups on these rollerguns and your learnings from testresults and experience in general.

@@martincjoergensen One day maybe. Most of our testing is in 27 deg+ water tamp. It's winter now and will try get my guys in the 17 def water 😜👍

@@RobAllenSpearfishing Oh you don't have to do that 😅🥶 It could just be a video with a discussion of your test results and experiences so far - you have a lot already It seems 🤙🙂

@@martincjoergensen We really need to do a temp comparison. Problem is, I need a cold pool and a heated pool to try the same gun the same day 😎👍

We have not done any testing on the double roller so I can't give advice, best would be to talk to Chris Coates.

Should be fine. Only issue is if the water is very cold, it will reduce the band performance equally no matter what band gun you use. Generally guys cut the bands shorter when using band guns in cold water.

Sorry we do but only to our distributor there. Fa’nu’i 570B West Marine Corps Drive Anigua 96932 Guam P: +16714826011 T: +16714776011 E:fanuiguam@gmail.com

@@roballen1578 Thank You sir! Appreciate the Reply! Love the videos and Gear! Will check him out asap! Guam 🇬🇺 Loves Rob Allen Si yu'os Ma'ase (Thank you) in Chamorro

Hi Steev, where are you in the world?

Hi Bruce, I will try do one when the factory fully opens. Pretty simple though, change the roller, drill out the handle screws and fit the rubber anchors. Cut and set the rubbers as explained in this video.

Perfect, thank you very much.👌🏼

@@RobAllenSpearfishing Always sensible and perfect advice. Challenge is stainless anchors nowhere available. Likewise Rob Allen master class spearguns. So SALVIMAR it is then.;-(((((

We find the Dyneema less likely to tangle and cause inaccuracies.

There is always one 🤣