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Author Topic: 50cm Rollergun for NorCal  (Read 786 times)

Offline Joshua R.

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50cm Rollergun for NorCal
« on: February 27, 2014, 12:46:10 PM »
Just put together a 50cm roller gun with help from my buddy Matt Davidson at Blue Tuna Spearfishing.  It's an Omer Cayman Sport 50 with a roller conversion.  The gun is only 32" total length from the butt to the tip of the spear and it seems more powerful than a 70cm.  I'll let you know hopefully this weekend for sure but I'm excited about it. 

The roller kits are on sale with BTS right now for $75, (normally $90), and the Cayman I put it on runs around $200.

Freedive shop also has roller conversion kits.









Offline jjjjeremy

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Re: 50cm Rollergun for NorCal
« Reply #1 on: February 27, 2014, 04:00:24 PM »
That's awesome!

Offline Sarge

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Re: 50cm Rollergun for NorCal
« Reply #2 on: February 27, 2014, 06:20:40 PM »
that is sweet bro.

Offline Joey

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Re: 50cm Rollergun for NorCal
« Reply #3 on: February 27, 2014, 10:26:39 PM »
Looks like fun Josh!  What size band are you running? 
- Joey

Offline Joshua R.

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Re: 50cm Rollergun for NorCal
« Reply #4 on: February 27, 2014, 10:46:09 PM »
9/16

Offline J.lata808

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Re: 50cm Rollergun for NorCal
« Reply #5 on: February 27, 2014, 11:06:48 PM »
Thats sick!!!

Offline natraps

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Re: 50cm Rollergun for NorCal
« Reply #6 on: February 27, 2014, 11:13:38 PM »
Where can I get a really good schematic explanation of the rollergun mechanism?
The Lord has given us the seafood; let us enjoy it.

Offline Joshua R.

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Re: 50cm Rollergun for NorCal
« Reply #7 on: February 28, 2014, 07:16:51 AM »
It's not the mechanism that's different, it's the band travel.  The bands attach at the front of the gun and travel to the rear where they go over the first set of rollers, then to the front of the gun where they go over the second set of rollers, and then go to the tabs on the spear.  What this means is that the bands already have tension on them in the resting position that can be adjusted.  Also that you can get much more distance on the pull than if the bands only stretched in one direction and since the bands are under tension all the way to the tip of the muzzle you get a little extra there too.  The band is always pushing the spear from the moment you pull the trigger to the moment it leaves the muzzle where traditional bands go limp when they reach their resting length. 

I drew a little schematic for you though.


[attachment deleted by admin]
« Last Edit: February 28, 2014, 07:21:49 AM by Joshua R. »

Offline Joshua R.

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Re: 50cm Rollergun for NorCal
« Reply #8 on: March 10, 2014, 07:07:24 AM »
Needs more tuning and testing. 

First shot was with the tip resting on the forehead of a 34" ling, (already on Dustins stringer,) and the spear just pushed the fish back.  Second shot from 12" away shot straight through the skull. 

Second shot was at a blue about 6' away.  The spear lost velocity as soon as it left the muzzle.  I could see it slow and drop.

conclusion: Currently the range is about the length of the spear.  Needs more tuning and testing but I'll be hunting with my weapon of choice and testing this one on the stringer.

Offline Dustinfulmer1

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Re: 50cm Rollergun for NorCal
« Reply #9 on: March 10, 2014, 07:28:23 AM »
Needs more tuning and testing. 

First shot was with the tip resting on the forehead of a 34" ling

Correction, she was 36" ;)

Offline phil herranen

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Re: 50cm Rollergun for NorCal
« Reply #10 on: March 11, 2014, 10:35:01 PM »
that gun is never going to work very well as is, its not using the full potential of the bands, or the roller concept, and there is a lot of parasidic drag from the extra roller and loading loop . 

if it was my gun i would put the "band roller" at the muzzle  , anchor the bands where the rear rollers are now , and make a new band that has about 30# to 40# at the muzzle . you can keep the muzzle loop bit make it just large enuff to get the band started . st up like this the shaft will fly .

phil

Offline Joshua R.

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Re: 50cm Rollergun for NorCal
« Reply #11 on: March 11, 2014, 10:42:28 PM »
Awesome!!  Thanks Phil.

Offline phil herranen

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Re: 50cm Rollergun for NorCal
« Reply #12 on: March 12, 2014, 09:12:03 AM »
i looked at the pics a little more and the muzzle will need a few tweeks also , it may be more work than its worth . in the mean time to make it better how it sits now .

measure the length from the band anchor ,all the way around the roller back to the muzzle , figure out the 3 to 1 rato for length  subtract about 5" and attach the band directly to the muzzle , have wishbone set up like you have it now ,but with a shorter loading loop (just long enuff for a finger or 2 to fit in to get the pull started ) give me a call or stop by if you are near my place and i will help you tune it up .

phil

Offline Lawdog (AKA "Ling Dinger")

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Re: 50cm Rollergun for NorCal
« Reply #13 on: March 12, 2014, 09:44:55 AM »
Needs more tuning and testing. 

First shot was with the tip resting on the forehead of a 34" ling

Correction, she was 36" ;)

Always telling people its two inches longer than it really is....!
"Josh Russo ruined my life"

 

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