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Gun Build Idea

Thread Status: Hello , There was no answer in this thread for more than 60 days.
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Mikegfx4

New Member
May 2, 2013
8
0
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So Ive been interested in spearfishing for a long time now and have been surfing threads about different guns. I never really loved the wood guns as I am much more of a metal working person. So I decided to make up a design of a sort of tube gun and this is what I came up with. I plan on mostly using this for freshwater ie: carp, catfish, whitebass etc


There will be a grip mounted on the back just havent found a cad file of one, it is designed to accept a m16 style pistol grip.

Figured I would throw it up here to see if anybody had some incite on possible problems.

Everything is made of aluminum other than the trigger, shaft catch, and hardware.

I figure I will need about a 15" band probably only one. I found this by finding the length from the muzzle to the knock to be 26.87" dividing by 2 and adding 2" which ends up at about 15", I found this formula on Spearboard.
How thick should this band be?

I have seen some guns that dont have a rail along the entire length of the gun, how badly does this effect accuracy? I was also thinking of buying a rail like the one in the link Rail is first on list

Also any ideas on how to seal off the tube? I was thinking rubber inserts with an epoxy or locktite of some kind.

Let me know what you think.
 
Have you done any buoyancy calculations? Seems like it will be seriously negative. Or maybe that is what you want?
 
No I haven't done any calculations as far as buoyancy goes. I would imagine it is going to sink which im not to concerned about because I dont plan on going to deep or being down for to long. But do you have any ideas to lighten it up tin man? I was thinking of possibly putting some wood on it, like the rail and maybe some wings or something if it is really really bad. Or I was also somewhat considering buying a CF barrel from the same website with the rails on it, but at that point i might as well just buy a new gun because its going to get pricy with the CF. Any ideas are welcome though, its just an idea at the moment but i do want to build it in the end.
 
You might consider using some plastics or G10 in places, instead of aluminum. Small guns are always challenging to keep the buoancy right, because there just isn't much reserve to play with. To keep cost down, you can always just buy a CF tube, and use one of the JBL tru-glide adhesive rails.
 
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Do you have any links to a place to buy cf tubes? Also do you think that only one band would be enough for the fish mentioned? How thick?
 
I have bought here before, because they are one of the few places I have found that offers shorter sections:

Medium Carbon Fiber Tubes

I don't have experience hunting the freshwater fish you mentioned, but from what I know of them I would guess that a single band would do fine.
 
Those are decent prices. Maybe an upgrade in the future if I want to and really like the system.
 
Did some more work on the design today. here is an updated picture with the rail and a new front. Found out the total weight (calculated by solid works) would only be 2.52lbs which to me seems extremely light but that's what it tells me.
 
You may have some trouble getting a wood rail to adhere well to the aluminum barrel. Aluminum grows with temperature, where wood (mostly) does not. Conversely, wood changes more with moisture, where aluminum does not.

Where will your shooting line be attached? If at the rear of the shaft, will the loop / crimp pass through the muzzle hole as you have it drawn?
 
I was planning on putting the shooting line just in front of the muzzle of the gun or prossibily having a slide ring so that it stays in front of the muzzle but can slide back when needed. I'm still trying to decide on a line release method also. And yes attaching the wood to the barrel is an issue I'm not sure if I'm going to Make the rails out of wood yet or what so it may not be an issue in the end but I was also thinking of using some small self taping screws from the wood to the barrel and then somehow sealing the barrel off again. Do you by chance have the measurements for that adhesive rail by jbl so I can tweak the model to fit that?
 
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They make two sizes, to fit 1" and 1.25" diameter barrels. I have a 1.25" size here. It is 0.77" wide at the base, and 0.26" tall. The lowest point of the track is 0.050" high (above the tube).
 
I would imagine that the height off the tube would be the same for both tube sizes. Ill see if i can tweak the design so that it is the right height for that.
 
Head down to Neptonics, I buy a lot of stuff from there, they have excellent trigger mechs and handles ect, Check out the Ulusub handle or Have a go at carving your own wooden one :) With that weight, it will have a larger recoil...much larger being only a couple of lbs. Speargun and Freediving Equipment
 
I would love to just buy a trigger mech but it is hard to do because I would have to desgin arround that and I dont have one to get the measurements off of in the first place.
 
I know that one of my mates built his gun around the trigger mech, he made a CF rail gun and I think it worked well. But thats the fantastic thing about building your own, you can build it how you like! :D
 
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