Gamo PR-15 360 m/s lead ball .177

[JAS]

Hi everybody! Please be nice to me, English is not my main language. :)

I had a old Gamo BB-gun that was kind of lame. Thougt I'd tune it up!

I stripped down the gun totally and flipped the barrel so the 'chamber' pointed backwards into the gun. (Many of the airguns on the market has a bigger hole in the end of the barrel to prevent damage to the rifling. On this particular gund this 'chamber' is very big, and can be used to fill with energetic materials.)

With the barrel flipped, I reinforced the loading block in the back of the gun with a steel plate, cause it was made of some composite material that would easily melt when I fired the gun.

With all that fixed and lined up I installed a 9V battery where the pressure chamber used to be, and installed a 'click' switch connected to the trigger.

To load the gun, I open it as usual, but instead of traditional pump action I load the 'chamber' with a bullet and after that a mix of PYRODEX and a tad of aluminum(to speed it up a notch). I put a thin twinned line of steelwool inside the chamber with the end of the wires in such a position that it connected to the circuit when I closed the gun. I have tried other high resistant element wires of different kind but the steelwool seems to light faster.

When I first testfired the gun I clocked the bullet with a chronograph to 360 m/s, this was with pure pyrodex. When I added the aluminum it went out of scale.. ERROR. Probably around 400 m/s. Thats about 1312 feet per seconds!

I have now tried different mixes and I pre-load some kind of homemade cartridges of tissue paper so the loading of the gun is kept as simple as possible.

I have documented some of the rebuild and can upload pictures in a while if anyone is interested!

It may sound like a difficult task but it is not that hard. Took me ten hours to get the basics done.

This gun stances nicely cut holes in an 1mm steel plate! Good for a ten year old toy pistol!

[stupid939]

I am sad to say that this may be the first banning I have been around for.

You should have read the rules before joining the forum and starting a post. If you are going to start a fresh post, and you are new, you should have something really important to share.

Personally, I think that this would be an OK post if you provided pictures and a more detailed description, but the admins may have a different opinion. If I was you, I would put up some pictures and describe it in more detail. You may still have a chance of staying around here, and good luck.

[nbk2000]

If you can provide pictures, and improve your grammar in the future, than all will be forgiven.

Otherwise...

[JAS]

If you guys give me a couple of days I'll make a proper write-up with pictures. As for the spelling, I think I'll come in to it. It was some time ago I wrote or spoke english. I'll do my best since this is the only forum of its kind around.

I posted this because I thougt it was a fairly simple conversion other may like to hear about and I had nothing useful to contribute with in the watercooler.

[zaibatsu]

I would be interested in seeing something similar to this 'http://www.ctmuzzleloaders.com/mlexperiments/electric_ml/electricml.html' but in a more easily replicated design. The problem I see with your design, as with most electrical ignition sources is how to set off the charge. Steel wool is at best a primitive means, and sparks won't ignite pyrodex. Also, how is the chamber sealed?

[file]

Maybe a coiled fillament like in a lightbulb might work to ignite the pyrodex

[zaibatsu]

I'm sure it would, the problem isn't ignition, any hot coil of wire will do that fairly well. The problem is replacing the ignition source with each shot. Without a reusable/self contained ignition source we are no further ahead than a matchlock rifle. However as the link I've given demonstrates the hot gas erosion problems provided by such a system. If they were relatively simple to produce, I wouldn't see a system that lasted 100 or so shots before needing to be replaced as such a hassle for the hunting of small game.

Any form of ignition where the element burns out after one shot and requires replacement is asking for trouble with accuracy, which I would think should be in the region of 1.5" or less from the point of aim at 50m, or around about 6MOA.

[mydnight]

I have no idea if this would work, or if it would be destroyed during the firing process, but would glow-plugs for a diesel engine work well? They are designed as re-usable electrical ignition sources.

[Cobalt.45]

Along that same line, a glow plug from a model aircraft engine would be much smaller, reusable, and cheap.

[ShadowMyGeekSpace]

One problem I see with the whole thing, is pyrodex leaves behind residue(lots of it) that could interfere with the igniter.

[festergrump]

I think a glowplug would be impractical because it would require too much time for it to heat up enough to ignite the propellant. (and people think flintlocks had a delay!). Remember, the old deisel engines that used glowplugs required turning the ignition switch to the ON position for a good while before turning over the engine. This was because they took a long time to heat up.

The smaller glowplugs Cobalt mentions might work better, but once you took your first shot you'd be a fool to load more BP or Pyrodex onto a hot glowplug for the next shot.

The steel wool idea would be slightly better as it burns up upon ignition and more would need to be fed in for the next shot.

The only thing I can think of better than this for ignition would be a percussion cap, and SMGS's thoughts about residue left behind would interfere alot more with such a small bore. Most folks who shoot frontstuffers give the bore a wipe after every couple of shots to remove the fouling, and that's with 1/2" bores or larger even! .177 is gonna foul out alot faster.

My thoughts are to just start over and build yourself a muzzleloader from the ground up. Can't be all that expensive. I kind of hate the idea of that modified breech plug/mechanism failing and launching right towards your face, too. (doubt you'll be set up to chronograph THAT projectile!).

[Cobalt.45]

And, with electrical ignition (via a resistance-type element scheme) will make the "lock time" so long that accuracy would surely suffer.

Truth be known, the whole idea is somewhat lame, but who knows where the next good idea may come from?

Often, brainstorming things such as this will spawn an idea that has applications outside of the intended area of inquiry.

[mike16]

I have a .22 cal break barrel air rifle which has been transformed to fire 30grain pellets using plain guncotton inside the barrel and a disposable nichrome wire attachment for ignition, and then a breach plug behind that.

When the barrel is closed it is locked with a 4mm steel bar pushed through a hole drilled in the breach block.

The barrel is about 6mm thick DOM type, its a Weihrauch rifle and will hold a lot of pressure.

It uses A 6V 750mAh rechargable battery wired to a two stage trigger, when fired it has no noticible lock time, it fires instantly when the wire on the back of the trigger touches the wire behind it.

The nichrome wire ignitor is designed to be completly disposable and is replaced after each shot.

I have yet to test accuracy and I do not know the velocity I'm getting.

I'm using about half a gram of guncotton for each shot, it sounds a bit louder than a .22WMR

[akinrog]

I think a glowplug would be impractical because it would require too much time for it to heat up enough to ignite the propellant. (and people think flintlocks had a delay!). Remember, the old deisel engines that used glowplugs required turning the ignition switch to the ON position for a good while before turning over the engine. This was because they took a long time to heat up.


It takes a long time to heat up because the glow plugs are used for heating the precombustion chambers of the diesel engines. Otherwise when they are energized they almost immediately glows with the major drawback that they need an enormous amount of current for glowing. Regards.

[stupid939]

I found this link on another thread.

http://www.geocities.com/elmgrove1765/

The guy who made this 4-shot pistol used model aircraft glowplugs and he said that they ignited "A bit slow - about 0.25-0.3 seconds."

He stated that if you cleaned the the plugs carefully, you can get up to about 15 shots per plug. Of course he used a CR123 lithium battery, so it takes a little while for the plugs to heat up. So, you can use them, but they may not be as easy to maintain.

[festergrump]

It takes a long time to heat up because the glow plugs are used for heating the precombustion chambers of the diesel engines. Otherwise when they are energized they almost immediately glows with the major drawback that they need an enormous amount of current for glowing.

It doesn't solve the problem of loading the powder for the next shot, but it DOES pose a challenge for proper current, though, and also reinforces my thoughts on delayed ignition. Hmm... yet another obstacle for this avenue of ignition nobody'd yet mentioned... the 9V current simply won't do. :(

The four-shot pistol that Stupid refers to might allow the plugs to cool down enough for a reload, but then again, there also is the delay problem staring us in the face.

I agree with Cobalt that from discussion comes invention (though it might relate to something entirely different in nature, or so I interpreted part of his post) and discussing this might work out for the best, somehow. :cool:

If there's ever been a great collection of minds all partial to one objective or idea... I think RS is the place to hash them out. ;) You cannot re-invent the wheel but you certainly can improve upon it. The best question to ponder is: Is the BP rifle/pistol/cannon where to return to in history to promote improvements or should we be looking more toward what we now have available technology wise?

I thought this thread began as a somewhat lame attempt at hurting oneself with a shitty pelletgun and some BP substitute... :eek: Please, people, help prove me wrong.

[FUTI]

I think that electrical ignition of any propelant is posible. It could provide faster firing rate (thats my opinion) of ammo and military would be very happy to have that, but fact that you need to make a ammo posible to "ignite" under relatively low voltage/current doesn't look like safe procedure to me. So i think that already is described in some place we didn't look so far, forgotten as unsafe as hell process.

[Cobalt.45]

I have a .22 cal break barrel air rifle which has been transformed to fire 30grain pellets using plain guncotton

That would take care of the residue problem, and might have good power to boot.

So, with a small glow plug or steel wool and a "hot" battery, and highly nitrated gun cotton for propellant, a rifled barrel shooting a 30 gr. pellet, we've almost made up something that probably wouldn't hold a candle to a .22 short.

But, the thing is, something just as "jury rigged" as this could: Put food on the table, put an assailant in the ground and wouldn't be "visible" to law enforcement, as it doesn't exist as far as the BATFE is concerned.

It sure would be better than nothing. This, along with a bow and arrows, a sling, a sling shot, a fishing pole and a frog gig could keep a fellow eating damn good around where I live!

[Mr Clemensen]

I had a old Gamo BB-gun that was kind of lame. Thougt I'd tune it up!
...
This gun stances nicely cut holes in an 1mm steel plate! Good for a ten year old toy pistol!

I never thought an airgun like this would be able to manage that kind of power, I would very much like to see your pictures of this modification, just for the fun of it.

[festergrump]

Think I'll be eating a few of my own words, now!

http://www.cva.com/products/rifle_electra.htm

Not just some basement/garage idea, anymore. This ignition system is past R&D, in production now, and uses... a 9 volt battery. :o

I want very badly to take one of these apart and see how exactly it works, however, I lack the $458 at the moment. I'd probably find out that it works on the mini-glowplug idea, too, much to my further chagrin...

Keeping in mind the "hot glowplug + fresh powder = BAD idea" thoughts, a certain TV commercial for a battery powered soldering iron comes immediately to memory:

http://www.asseenontv.com/prod-pages/heat_cold_soldering_set.html

Hmm, "Three seconds and cold to the touch" is not bad at all! :cool: It'd take me at least that long to measure out another charge for it.

[tomu]

This might be of interest to anyone intending to build an electrically fired BP gun:

http://www.ctmuzzleloaders.com/ctml_experiments/electric_ml/electricml.html


Another link to the patent claim of the CVA "invention":

http://www.freshpatents.com/Electronic-ignition-system-for-personal-black-powder-firearms-dt20050901ptan20050188872.php

It looks like a cap-discharge system to me nothing really exiting.


And I wonder if this little gadget would be usefull in getting the BP going:

http://www.technologie-entwicklung.de/Gasturbinen/KJ_Starter/kj_starter.html

Look for "The Zapper".

How about using a Dazer like this as an ignition system:

http://www.uoguelph.ca/~antoon/circ/hv/dazer/dazer.htm

[mike16]

This post is to describe how my "converted" air rifle works using my nichrome wire igniters I have described in another post.

Summary:

>22 cal, it fires 30 grain "piledriver" pellets back to front so they are hollow point. (I use pellets because jacketed bullet heads are very expensive here in the UK).

>It uses highly nitrated, fast burning guncotton pressed into an aluminium case which is sealed into the breach with a steel breach plug, only some, maybe 5% of the hot propellant gasses escape out of the breach.

>The priming system is electronic, I have two wires behind the breach which are connected to the wires on the nichrome igniter, when I pull the trigger back to the second stage, it presses a small button which sends the current from a 9v battery to the nichrome wire, immedietly igniting the guncotton.

OK, firstly here are pictures of making the cases:

Guncotton:http://i155.photobucket.com/albums/s300/kpppppk/Picture007-1.jpg

Some nichrome igniters:http://i155.photobucket.com/albums/s300/kpppppk/Picture008-1.jpg

The aluminium cases which are 40mm long:http://i155.photobucket.com/albums/s300/kpppppk/Picture009-1.jpg

A igniter is primed with guncotton by threading a peice through the nichrome loop:http://i155.photobucket.com/albums/s300/kpppppk/Picture011-1.jpg

The igniter is then stuck to one end of the case with a small peice of selotape:http://i155.photobucket.com/albums/s300/kpppppk/Picture013.jpg

The case is then rolledaround itseld to a diametre of about 5mm:http://i155.photobucket.com/albums/s300/kpppppk/Picture015.jpg

The case is filled with guncotton by pushing it into the case:http://i155.photobucket.com/albums/s300/kpppppk/Picture019.jpg

And the back, when the case is full I stop adding guncotton:http://i155.photobucket.com/albums/s300/kpppppk/Picture021-1.jpg

Here are some finished cases:http://i155.photobucket.com/albums/s300/kpppppk/Picture026.jpg


I would guess that each case is filled with around 4-5 grains of guncotton, I don't know exactly as I don't have a weighing machine.

Here is a picture and a diagram of what the setup looks like in the bore:http://i155.photobucket.com/albums/s300/kpppppk/Picture023.jpg
http://i155.photobucket.com/albums/s300/kpppppk/rifle1.jpg

The barrel plug:http://i155.photobucket.com/albums/s300/kpppppk/Picture024.jpg

The pellet:http://i155.photobucket.com/albums/s300/kpppppk/Picture025.jpg

To load the rifle, the pellet is put into the breach then pushed about 2.5 inches into the barrel with a small screwdriver, then the case and barrel plug are pushed into the barrel behind the pellet.

Here is a diagram and pictures of how it works:http://i155.photobucket.com/albums/s300/kpppppk/gundesign.jpg
Case is pushed into the breach:http://i155.photobucket.com/albums/s300/kpppppk/Picture031-1.jpg
then pushed right into the barrel:http://i155.photobucket.com/albums/s300/kpppppk/Picture032.jpg
The barrel plug goes in directly behind it, and pushed in:
http://i155.photobucket.com/albums/s300/kpppppk/Picture034.jpg
http://i155.photobucket.com/albums/s300/kpppppk/Picture036.jpg
The breach plug is a tight fit onto the bore, so its a good seal.

The barrel is then closed and the two wires connected:http://i155.photobucket.com/albums/s300/kpppppk/Picture039.jpg

Here is a picture of the trigger unit with:http://i155.photobucket.com/albums/s300/kpppppk/Picture041.jpg
When pulled back the 1st stage, it touches the button, when pulled back more, it presses the button which fires the rifle:http://i155.photobucket.com/albums/s300/kpppppk/Picture042.jpg
Pictures of two used cases, notice how they have expanded from the pressure of firing:http://i155.photobucket.com/albums/s300/kpppppk/Picture049-1.jpg

Here are pictures of the rifle:
http://i155.photobucket.com/albums/s300/kpppppk/Picture045.jpg
http://i155.photobucket.com/albums/s300/kpppppk/Picture046-1.jpg

After firing the rifle, you open the barrel and pull out the old case to reload, sometimes the taped wires get detached from the case, so I use a small hook to stick inside the barrel and pull them out.

As I have don't have a chronograph, I don't know exactly how fast these pellets are going, but when I fire the rifle, I can hear the sonic crack, so I'm geussing they are probably moving at aroung 1500ft/s.
The accuracy is not perfect though, at close range within 50 yards, I can hit within 3 inches of the target.

[mike16]

After I completed my converted air rifle, about 2 months ago using the electronic ignition system, I thought what if I used this lightweight low voltage ignition system on a new device, maybe something smaller, maybe a pistol design.

I was lucky enough to have 16 inches of spare .22 calibre german made air rifle barrel, which I decided to cut into two sections, one was 7.2 inches long and the smaller was 5 inches long.

Here is a picture of the two barrels:http://i155.photobucket.com/albums/s300/kpppppk/1Pictureofbarrels.jpg

After the barrels were cut, the muzzle was filed and polished with a file, and the muzzle crown was cut with a large drill bit.
Here is a picture of the muzzle:http://i155.photobucket.com/albums/s300/kpppppk/Picture007-2.jpg


Anyway I found a plastic toy pistol, took it apart and cut a few bits inside so that I could fit a 9volt battery inside the handle and the barrel could slide into the top.

Here is a picture of the plastic pistol taken apart ready to be reassembled and have the wire stuck on:http://i155.photobucket.com/albums/s300/kpppppk/3Startingmaterials.jpg

The barrel slides into the plastic pistol and is a tight fit to prevent it from falling out:http://i155.photobucket.com/albums/s300/kpppppk/14Barrelslidingintoplace.jpg

Here are more pictures:http://i155.photobucket.com/albums/s300/kpppppk/15Barrelinplace.jpg

http://i155.photobucket.com/albums/s300/kpppppk/Picture015-1.jpg

The trigger works exactly like that on the rifle, but uses bare copper wires instead of a push button, as I do not yet have any spare push button switches:http://i155.photobucket.com/albums/s300/kpppppk/17trigger1.jpg

http://i155.photobucket.com/albums/s300/kpppppk/18trigger2.jpg


The firing mechinism works exactly like the converted air rifle, with a case inside the barrel full of guncotton, a breach plug behind that, but as the breach end of the barrel in this case is exposed, I have drilled a 4mm hole 3mm from the end of the barrel , so that I can fit a steel “breach plug stopper” to keep the breach plug from being fired out the end of the barrel from the pressure upon firing.

Here is a diagram and picture to help describe this:http://i155.photobucket.com/albums/s300/kpppppk/4Planofdesign.jpg

This design uses slightly shorter 35mm cases full of guncotton and fires the same 30 grain pellet, Here is a picture of the case and setup:http://i155.photobucket.com/albums/s300/kpppppk/5Pictureofdesign.jpg

Here is a picture of the breach plug and breach stopper:http://i155.photobucket.com/albums/s300/kpppppk/7Breachplugandstopper.jpg

The breach plug is 5mm wide, made from part of a 5mm steel drill bit and is a snug fit inside the barrel.
Here are pictures of the loading procedure:

Case pushed inside barrel behind pellet:http://i155.photobucket.com/albums/s300/kpppppk/8Casepushedinsidebreach.jpg

Breach plug pushed into the barrel behind the case:http://i155.photobucket.com/albums/s300/kpppppk/10breachplugpushedinbehindcase.jpg


Breach plug pushed 10mm into the barrel and the plug stopper is pushed into the hole so that it is directly behing the breach plug:http://i155.photobucket.com/albums/s300/kpppppk/11Breachplugpushed1cmintobarrel.jpg
http://i155.photobucket.com/albums/s300/kpppppk/13.jpg

The safety switch is checked and the two wires connected tone the igniter.

Here is a picture of the rifle and pistol together, with a few ready to use cases:http://i155.photobucket.com/albums/s300/kpppppk/Picture032-3.jpg


One thing I like about this pistol is that it is all plastic, only the barrel is the metal part, and the barrel can be switched with a new one or simply removed from the plastic casing very easily and quickly, it simply slides out.
Here is a video demonstrating the barrel removal:http://s155.photobucket.com/albums/s300/kpppppk/?action=view&current=Interchangablebarrels.flv


Here is a video showing how the guncotton ignites when the trigger is pulled:
http://s155.photobucket.com/albums/s300/kpppppk/?action=view&current=GuncottonIgnition.flv

All of the pictures and a complete document with pictures has been uploaded to rapidshare.com :

Pictures only:
http://www.rapidshare.com/files/27311968/Pistol_plans.rar.html

http://www.rapidshare.com/files/27167812/Rifle_Pictures.rar.html

http://www.rapidshare.com/files/27211136/nichrome_igniters.rar.html

Here is the link to all three completed documents with pictures included within the documents for the nichrome igniters, rifle pictures and pistol plans:

http://rs142.rapidshare.com/files/27349010/guncotton_projects.rar

Soon I will get some videos uploaded of the rifle and pistol firing.