Over powering a band gun

[Newbie_spearo]

Hi all,
I am about to start making my own 1.4m enclosed track tuna gun. I am in no rush as I have about 8 months if not a touch more till the tuna come back. My query is can I instead of having 3 16mm bands just use 2 20mm bands? would there be an issue or will it be pretty much the same to shoot? The reason for my question is that I'm hoping to use a Rob allen mech, but robs tabbed spears still only have 2 tabs and as a result I can only use 2 rubbers unless of course I can load 2 rubbers onto 1 tab? I realise using 20mm rubbers will make loading more difficult but I got enough powder in my cannons:martial for that and being a tuna gun I won't be reloading a thousand times, hopefully only a few if I can put a shaft in one. That's enough ranting from me, cheers!

Jono

 

[foxfish]

Sounds fine to me, 2 x 20mm at 2.75 stretch on a 1.4 gun is going to be difficult to load but will have plenty power.

 

[Newbie_spearo]

I've got long arms:t
Thanks fox

 

[kmo]

I would check with Rob Allen on using that much power with his mech. What size spear are you hoping to fire?

 

[Newbie_spearo]

I spoke to jeremy at RA in SA and he said he would'nt load 4 16mm on their current mech. I'm waiting for their stainless mech to come into production, not sure if it will be any different with regards to the load it can take but I'm doing my homework so I can do things once and not mess around.

 

[foxfish]

How do you plan to construct the gun? What about the track - derlin or epoxy?

 

[Newbie_spearo]

Still deciding on how many laminates I want to use. But I will be buying the router piece from neptonic systems and will use wood for everything I can. Riffe seems to be the most likely trigger mech I will use. I was going to use 10mm laminates but I am now thinking I will go with a centre laminate of about 7mm, or the same thickness of the riffe mech and then use 15mm laminates and have the stock 100mm wide at the butt and 50mm wide at the front.

 

[foxfish]

So are you buying a bit to cut a round enclosed track or a bit to fit a derlin track?
I have fitted the trigger units slot into the laminate layout before you glue up, you best buy the trigger before you cut the lams then.
What type of wood?

 

[Newbie_spearo]

Buying a bit to cut an enclosed track. I plan on getting all my bits and pieces before I start any proper construction. I will mess around with pieces of pine first to make any mistakes with and then the final project will be US Walnut and American Ash. Nice contrast in colours. handle will be fashioned out of wood, I am lucky enough to have a member at my club who has built quite a few guns and is showing me a few tricks of the trade and helping me out a little.

 

[foxfish]

Is there a reason to choose Walnut & Ash? They are very dense & heavy woods, of course you might want a heavy gun?
I dont have any experience building big game guns so I am just assuming but dont you want high mass rather than high weight?

 

[Mr. X]

Did you ask Jeremy/Rob Allen if they make or would a 3 notch spear for you? I believe they make their own spears (and for other companies) - I believe they can be quite accommodating with special orders (for spearguns anyway).

If not, perhaps Mako their website show 3 band guns on their website and offer 3 pin spears:
MAKO Spearguns - Iconic Pro Railgun (Black)

Carbon Steel
Shark Fin or Pinned Tab shafts
3 Pin Tabs for guns 130 & 140
2 Pin Tabs for guns 100,110,120

 

[Newbie_spearo]

Fox, from what I have found out on google both walnut and ash are lighter than teak, and considerably cheaper over here. for the same size blank in walnut ash and teak I'm looking at $40 $20 and $80 respectively. The gun is basically going to be a cannon, so I'm gonna be sitting mid water focusing on some burly and when a fish comes in fire. I am in no way expecting it to be nimble and easy to maneuver. I will however make the stock as hydrodynamic as possible in shape, so kinda squid shaped.

Mr. X thanks for the tip, I will see what rob can do, I might even see if he can make a spear to fit the riffe mech? Not sure if it's as easy as that but I would much rather use robs gear and get it from him due to the price. I have family over there so getting the gear is no issue.

 

[jtkwest]

get the mech from neptonics. his triggers are solid! you could not over power that trigger with 7 bands. literally! i have used 5 so far and everyone loves them! fitting it is the easiest of all the brands i have seen. an imperial size 1/2" router bit is the exact size for the trigger slot, making it very easy. alexander and kitto are two other american brands thatare really good. another thing, teak is more resilient to salt water than pretty much anything. if you use the wood you mentioned you will have to really coat it with varnish or epoxy to keep the water out. especially in the trigger slot area and all the holes drilled. teak doesnt have that problem all you have to do is oil it once in a while. if you want to see a gun done the way you are talking, look at hamilton spearguns, he is making a very similar gun with mixed laminates. really really beautiful guns, very expensive also. i myself am switching from teak to bubinga. this wood is a little more dense than teak but at 10$ a board foot, compared to 40$ a board foot for teak. i am even considering mohagony, any way GOOD LUCK!

 

[nigelr]

Have you looked at using jarrah? Should be able to get some prime quality for a good price. Strong and resilient, very good to work and very attractive as well.
Should be easy to find in Melbourne.
Cheers and good luck with your project.