Enfield light harpoon rifle: Possible project.....

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PAINTBALL GUY 3

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Hello all.

I come here today with an idea, one that I know is nothing new. I've been given a Lee Enfield that's, to put it lightly, a "hack job". Action is still very good, she's just a tad mistreated. What I would like to do with her is: make something unique of out of an ugly duck and gift it back to a very good friend of mine.(Who is also the original giver.:p) And I think a harpoon launcher would be quite a unique piece. I've been searching on the Greener light harpoon guns, but not much is said about them other then one was used in the Movie Jaws. I just have a couple simple questions that I'd like to theorize over.
(search: Greener light harpoon gun)

1. So we're talking about setting off a round with a "really" heavy bullet in front of it. I can see that being something that, if proper precautions are not taken, may put undue stress on things. Especially on the length of barrel to be turned down to except a harpoon. I cant see making a harpoon out of a lighter metal like aluminum, so steel is key. And the length of the harpoon is a factor in both weight, as well as flight? Thoughts on these?

2. I guess the burn rate of the powder used would matter quite a bit? (and may also answer question one) I want to stay with the .303 chambering and load my blanks, so that experimenting with power levels and ranges can be done. I cant see crimped blanks being very "reloadable". Any ideas as to what powders could be used for an application like this?

3. And I guess this is the most important question (yet somehow made it's way to #3 on the list): anyone foresee any legal issues? I'm thinking it would still be considered a firearm, yeah?

Tool's at my deposal:

South bend Heavy 9" lathe (16" work length)

Mig/Gas/Stick welders.......welders.

Misc. other shaping and forming hand tools

In other words: a well equipped shop.;)

Thanks all.

Ti

P.S If I need to elaborate, please ask that I do so.
 
There are two ways of launching oversized projectiles - a rod down the bore, or a hollow tail over the barrel.
These function in the same way as a spigot grenade launcher, the hollow based projectile slides over the barrel. The harpoon is blown off the barrel. Very much like a rifle grenade.
The harpoon is most likely a lot lighter than a grenade, which would reduce pressures.

Do not under any circumstances consider using military noise making blanks. The military used different blanks for launching grenades or line throwing.

You would be sailing into uncharted waters if you want to play with this idea. Lots of potential for harm.
 
I've been given a Lee Enfield that's, to put it lightly, a "hack job". Action is still very good, she's just a tad mistreated. What I would like to do with her is: make something unique of out of an ugly duck and gift it back to a very good friend of mine.
Click to expand...

You had me right up until "harpoon launcher" :D

How about something more historically significant ???

delisle1.jpg


Just a suggestion ....... :cheers:
 
tiriaq said:
There are two ways of launching oversized projectiles - a rod down the bore, or a hollow tail over the barrel.
These function in the same way as a spigot grenade launcher, the hollow based projectile slides over the barrel. The harpoon is blown off the barrel. Very much like a rifle grenade.
The harpoon is most likely a lot lighter than a grenade, which would reduce pressures.

Do not under any circumstances consider using military noise making blanks. The military used different blanks for launching grenades or line throwing.

You would be sailing into uncharted waters if you want to play with this idea. Lots of potential for harm.
Click to expand...


Yes, there was one site I found (a marlin fishing forum) where a fellow had turned an H&R single shot gun into a harpoon gun by boring out the choke and stuffing his "harpoon" down this thing. I would rather take the exterior approach thou, for slimplicity and aesthetics.

I dont even want to bother with production blanks because, as you seem to indicate, there is an unknown. With loading my own, I could work around with the loadings untill I reached a comfortable charge. Now, I'm not a reloader as of yet. (thou I do have unconditional access to reloading equipment) But I would think that a slower burning powder would be safer to use as the harpoon would need time to "speed up" do to the weight. Seem like a fair assessment?

I thank you for your concern Tiriaq. I understand that this is not a subject that's in your average "how do I " thread. As with any altercations done to firearms, there is a level of danger. But It's been done, that is for sure. If Greener did it with Henry Martinis, it should be feasible to assume that the same could be done with an Enfield, no?

Edit: Joe-Boy - You know, I've thought about doing something like that for a future project, changing over to .45 ACP and everything. It would be an awesome little carbine, thats for sure. But maybe for a later date......;)

Thanks.

Ti
 
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I shot a martini style Greener harpoon gun about 15 or so years ago. It kicked like a mule. The one that I shot (commercially made) as I recall used a 38 blank in the head and had a hollow shaft with a firing pin that ran all the way down the shaft.

cheers mooncoon
 
Noise making blanks use a very fast burning powder, that would burst a barrel if used with a projectile.
.303 grenade launching blanks used a powder called "Ballistite".
With a spiggot launching system, the tail of the harpoon has to be able to hold pressure. I would suggest CrMo seamless aircraft tubing.
The only harpoon guns with which I have any experience were the two that were used in the first modern hunts to take bowhead whales in the Eastern Arctic. These were 8ga, and fired an explosive 1 lb bomb about 14" long. I prepared the bombs and launching blanks for the first hunt in Cumberland Sound. Launching and bursting charges were black powder.
 
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Mooncoon - That is very intresting. That would be similar to say a model rocket. Hmmm......

Tiriaq - Well, thats cool! ;) I’ll have to check around for that tubing. I know a fellow who, to put it lightly, is a god among men when it comes to building just about anything mechanical. And as such, has the supply’s to do it all with. He may have what I need.

And for the powder: So, you guys using black powder would tell me that a slow burn rate is necessary. So then a BP substitute should be fine, I would think?


Thanks.

Ti
 
joe-boy said:
You had me right up until "harpoon launcher" :D

How about something more historically significant ???

delisle1.jpg


Just a suggestion ....... :cheers:
Click to expand...

I'd be all over that in a New York minute... if we were allowed to own one :( Would be very useful when the 'yotes start eyeing the neighbour's chickens. Thwwwwwwip...! 'Yote down. And no one would know. (For those not familiar with this piece of history, google "De Lisle Carbine.")
 
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josquin said:
I'd be all ove that in a New York minute... if we were allowed to own one :( Would be very useful when the 'yotes start eyeing the neighbour's chickens. Thwwwwwwip...! 'Yote down. And no one would know. (For those not familiar with this piece of history, google "De Lisle Carbine.")
Click to expand...


So would I! But alas, anything like that has got to be a baby killing, gang banging, bank robbing tool of mass terror and destruction up here in Candy Land.........
 
PAINTBALL GUY 3 said:
So would I! But alas, anything like that has got to be a baby killing, gang banging, bank robbing tool of mass terror and destruction up here in Candy Land.........
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Too true. I don't have one and (as a result) I haven't been tempted to do any of those ghastly things you mention. But about a year ago the RCMP here found a grow-op and among other things found... a suppressed rifle.

I was just watching one of "hickock 45's" recent videos where he was shooting a CZ75b fitted with a suppressor. Seriously cool. But he has a 40-acre spread with his own range down there in Tennessee, so he can do those things.

:) Stuart
 
OK, so here's a question regarding the barrel. How am I gona take that thing off the receiver? The thread right below this one seems to indicate that removing the barrel from an Enfield is quite the task, needing special tools. True? My Enfield is a Mk 3, just to be clear.
 
PAINTBALL GUY 3 said:
OK, so here's a question regarding the barrel. How am I gona take that thing off the receiver? The thread right below this one seems to indicate that removing the barrel from an Enfield is quite the task, needing special tools. True? My Enfield is a Mk 3, just to be clear.
Click to expand...

IF you don't need to keep the barrel intact ..... chuck it up in the lathe and feed in a parting tool at the barrel shoulder/receiver junction, (without touching the receiver obviously ! ) about an 1/8" or so. This will relieve the tension on the threads and making spinning the barrel off a breeze.

If you want to keep the barrel intact, well it will be more difficult:D
 
The burn rate of the powder is actually not a big deal one way or the other. Far more important is the size of the apparent chamber where pressure builds up.

We see a perfect example of this between 9mm and .38Spl. Powder amounts which produce low pressure in the relatively large volume of a .38Spl cause magnum like pressures when used in the much smaller volume 9mm case.

So the key to making this harpoon rifle not explode in your face is to use a blank but at the same time to leave a goodly amount of volume in front of the blank so the initial burn and pressure rise which occurs before the harpoon really begins to move much or any at all has enough volume that it does not produce a massive pressure spike which is higher than the chamber can tolerate.

On a regular round the far lighter bullet begins to move even while the powder is still burning. This produces the effect of the chamber growing in volume as the burn progresses and that reduces the pressure rise. Again we see examples of this in regular cartridges where the lighter bullet options require more powder to reach the same pressure. In the case of a big heavy harpoon shaft stick in the bore this won't work. The mass of the harpoon will be such that it simply won't move appreciably during the burn. So you need to provide some room in the barrel near the chamber so that as the volume is large enough that you don't exceed what the barrel can survive.

When it's all said and done though I suspect you're going to find that you won't use even half the pressure that the chamber and barrel are capable of withstanding. The weight of the harpoon will give such a recoil even with lower pressure that it will easily be your shoulder that is the limiting factor.

In the end what you need is an internal ballistics/pressure calculator as a guide to sneaking up on a workable chamber size and load for your proposed beast.
 
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