Enclosed track speargun

Here it is, Hau's new hole gun. The first RA 15 cm. I think this barrel will work very well. It is really stiff, and while the OD is just a tiny bit large, it can easily be sanded down to fit inside the skirts on the barrel and muzzle. The track is cut with a 0.305" diameter ball, leaving nice a nice fit on a 9/32" shaft.

I would need to machine the skirt just a little wider to extend the track all the way back into the handle, but that would be easy to do.

Here you can see the faint lines left over from whatever they use to wrap the outside when fabricating the barrel.

Things went pretty much according to plan on this little test piece. I do not see any "show stoppers" at this point that would keep me from making a longer barrel the same way. I used a scrap of the standard "ghost green" G10 for this test, but Griswold has some black material that i would use for the real deal.

What do we need to change / improve Hau?

Joking aside, this is it? A CF pipe with a track glued on top?

We can make it more complicated by wrapping additional CF around the whole thing, but I really don't see the point. The additional CF would add weight, and would have to be removed at each end to fit into the muzzle and handle. It will take some semi-destructive testing to make sure that the bond between the track and tube is adequate, but I think that it will be.

There is more than one way to do this, to be sure. I like the way I did the CF track on my recent gun, but that is VERY time consuming, and couldn't be done to match existing RA handles or muzzles. On the other hand, I could modify a barrel like this in about 8 hours total work time and put an existing muzzle and handle on for a quick turnaround. So I guess it's all about what you really want from the end product.

Hau - I don't have a 9/32" spear with a Euro notch to check it with. a standard 9/32" Riffe shaft fits nicely, but I didn't try to engage it in the mech.

Where are you going to get a 9/32" spear with a euro notch and shark fin tabs, by the way?

I can shape the round notch on an American shaft.

What is the track made of? If the material is ideal is it available in black? What is used to bond the track to the barrel? Can the track be shaped to provide a smoother profile between the track and the pipe?

Quote from Dan

I can shape the round notch on an American shaft.

What is the track made of? If the material is ideal is it available in black? What is used to bond the track to the barrel? Can the track be shaped to provide a smoother profile between the track and the pipe?

The track is G10, which is a high pressure epoxy laminate. It should work like a poured epoxy track on steroids. The standard color is the ghost green, but it is available in lots of colors on a custom order basis. But you would have to buy a whole sheet, which is pretty expensive. Since the G10 is epoxy based, and the carbon fiber tube is epoxy based, I just used West Epoxy to glue them together.

If Hau has trouble finding the right shaft, I could machine a couple of standard Riffe shafts with the proper Euro notch.

Quote from Dan

Can the track be shaped to provide a smoother profile between the track and the pipe?

Somewhat, but I can't do much without getting thin on each side of the track. I need to start with a 5/8" wide stick because that is the size that Griswold has in black. Keeping it square also makes it much easier for me to accurately hold it in my mill for machining. That is particularly important with a longer barrel, where I must cut, reset, and cut several times.

Doesn't Riffe makes a 9/32 euro shaft with sharkfins already? Or is the notch different on the rob allen guns? Sorry for the questions but I don't have any experience with rob allen spearguns.

Also if you could blend/fair the ends of the G10 to the muzzle/handle it would look better. I know it's a prototype so you probably though about that already.....:)

Quote from psychobilly

Also if you could blend/fair the ends of the G10 to the muzzle/handle it would look better.

Agree 100%. I will definately fair it on the real gun.

have u lightlly tested the strngth of the connection between the rail and the barrrel? like jsut a tug or two?

I haven't hit it with a hammer, but I did my absolute best to break it off by hand and could not.

well thats all thats probably necessary id think..

Quote from hau

sdeisen---IMO, I think that many here would agree that the worst case REAL LIFE senareo for an enclosed track gun is when the shaft is fired and the shaft hits something solid before the shaft TOTALLY exits the enclosed track. IMO, this is when the enclosed track is stressed the most and when most enclosed tracks tear out. What that means to me with this 120cm ETPGB is that I cannot shoot the ETPG towards any hard coral back stop LESS than 40in from the end of this gun without concern for the safety of the ET.

What size bands and how many?
Don