Full auto behaviour, a technical idea

[BlackFalcoN]

Lately I've been dreaming about creating a way to convert a semi-auto weapon into full-auto behaviour, without having to modify/replace any mechanical parts of the weapon.

A semi-auto does the firing/loading sequence for the firer almost as quick as he can pull the trigger, so squeezing the trigger really-really fast, should result in really really much bullets leaving the muzzle.
Thus, a device that could squeeze the trigger much faster than a standard Mark1 human finger, would be the solution to achieve 'full auto' fire ( technically it's not full-auto, since every pin strike has to be achieved by pulling the trigger -- but the result at the muzzle end /target is the same :D )

Since Google is my friend, I found out that such a device already existed, called the 'GAT Trigger System'.

This basically is a device that is clamped on the trigger guard of the weapon and that pulls the trigger for the user.
The user just has to rotate a crank on the side of the device, which should result in four trigger squeezes for every rotation made by the user. ( inspired by the old Gattling Gun)

A video of the device can be seen here: http://www.gungarage.com/hellfireggr.wmv ( 2:40 - 4:10 )
( Just ignore all the other (crap?) products and sales-talk in the video :rolleyes: )

Since insane trigger-pulling is replaced by insane crank-rotating, (resulting in inaccurate fire, since both hands should grip the gun to deliver accurate fire IMHO :confused: ) I was wondering if it would be possible to replace the crank wheel on the side by a pulley (gear without teeth), and rotate the pulley with a small motor attached under the GAT-system. (connecting the two by means of a belt). The motor would be started/stopped by a pressure switch, that could be mounted in the grip of the gun.

A visualisation made in MS PBrush of this idea can be found here:
http://img93.imageshack.us/img93/7495/gat1qe2.jpg

In this example, I'm using a small cheap 12 volt, 1800 rpm motor, which transfers it's rotation power to the GAT System via a 1:6 pulley setup ( resulting in 300 rpm on the GAT -- but since every rotation is four trigger pulls, that would theoretically allow the trigger to be pulled at 1200 pulls per minute )

If this idea is technically doable, then it would allow to convert any semi-automatic weapon (pistol, a civilian semi-only rifle, shotgun, ... ) into full-auto behaviour in just minutes, without having to alter the internals of the weapon in any way.
The weapon will still allow to be used in single shot mode on the spot, requiring you only to pull the trigger as before (instead of pressing the full-auto pressure switch)

However, I would like some input and advice in this design.

1) Is there anyone who has experience with the unmodified GAT-unit ? Any review, comment would be useful
(I'm not talking about other trigger systems made by the same manufacturer, which are considered to be pieces of shite by most reviews I read on them. )

2) Will the GAT-System allow this modification ?
I can only watch the GAT on pictures on the internet, I'm fairly certain the crank is attached to the unit by means of a nut that can be unscrewed. Is this really the case ?

3) How much force is required to rotate the crank ?
Would it be more/less than the trigger pull (lbs) of the gun ?
( Since I see the crank being turned by a single finger, I assume the force is not that great, but again, I don’t have experience with these units, so clarification is needed )


Any suggestions on this idea / design would be greatly appreciated.

If the general idea behind this is technically sound and doable, I will dream about realizing this setup soon.

[cletus]

Your idea is intriging but may wind up too cumbersome for a standard rifle. It would be right at home on a tripod mounted semi auto belt fed like a 1916 browning.

Imagine running a 250 round belt of 30/06 downrange in less than a minute all perfectly legal. You should have your motor run on 12 volt DC, that way you could utilize your vehicles electrical source also a car battery would fit snugly in a20mm GI ammo can.

++++

Please notice the changes made to your post. Follow standard grammar rules, like CAPITALIZING the begining of EVERY sentence, as well as abreviations, such as GI. Thank you.

NBK

[nbk2000]

Electrically powered devices are illegal.

But fuck it, eh? :)

[billybobjoe]

The McMaster Carr part number is eluding me, but a pneumatic rotary actuator. It measures about 3 cm by 3 cm by 6 cm, and has two 1/8" hose barbs sticking out of it. It also has a 5/16' shaft with small key way. So it pulley would be a piece of cake to attach, and it would be powered by a 20 oz co2 tank or similar. Now I realize this adds another few steps, and a lot of complication, contrary to K.I.S.S. But a palmer low pressure regulator set to 60 psi, some 1/8" hose and an inline blowgun and then discharging into the atmosphere shouldn't be too overly complicated to built. And much higher rpms could be achieved. Maybe this would be a loop hole, if nothing else some food for thought.

[tomu]

Years back devices like the GAT trigger were sold which worked like a clockwork. The user wound them up before use and after pulling a trigger on the device the spring actuated system fired the gun very much like a full auto.

I'm not sure this device are still legal, I guess a look at shotgun news would reveal the availability.

[BlackFalcoN]

cletus - It all really depends on the size of the DC motor that is utilized.
Since the connection between the pullies is by belt, the motor could be placed anywhere relative to the fixed GAT-system, as long as the belt was adjusted in length.
If the DC motor isn't too heavy and the weight of the motor is well placed so it doesn't imbalance the gun, a mobile system could be realized.

NBK - It all depends on your location and local gun laws.
The device doesn't alter the original gun in any case. All it does is replace finger motion.

So if we would call it a 'cybernetic finger prosthesis for the shooting impaired' (patent pending :p), then what government could possibly oppose that ? One can't be blamed for trying to help his disabled shooting buddy right ? :D
( if they do oppose, well yeah -fuck it-, we are just discussing the theoretical design of this unit, it's still up to the sole reader to check with his local gunlaws if it is allowed to construct it and decide whether he wants to actually construct the device)

billybobjoe - higher rpms would be nice, but since the GAT system multiplies every rotation by four, 100-300 rpm is all that's really necessary on the GAT-shaft, because most guns aren't going to surpass 1200 rounds per minute fired anyway. 1200 rpm = 20 bullets fired PER SECOND (imagine the bolt travel and recoil on some guns :eek: ). This would clear out even the biggest magazine/belt/box in seconds.

Your design with an actuator would work I think, but it does have some drawbacks such as availability of parts, ease of construction, and availability of air / CO2 tanks. Imagine being in a tactical situation where you suddenly find your CO2 tank being empty or punctured. It's a good alternative / extension however for those who would prefer it.
Batteries are more common and easier to use I think, and would allow for a 'juice meter' to be attached, so you can check how much current is still available.

It would be really nice if we could figure out how much force is required to rotate the crank on the GAT system, so we can have an idea about what DC motor would be necessary.


An improved version of my design would incorporate a stepper motor, so the rotation of the pulleys could be controlled EXACTLY, allowing for multiple burst and speed options as well as single fire shots etc. However, this would involve extra electronics and a more complicated design, so I didn't mention it in the original design for the sake of keeping it simple and being realizable for the average user. However a stepper motor design would be far superior in the area of controllability to the 'basic' DC-motor design.

[Docca]

technically it's not full-auto, since every pin strike has to be achieved by pulling the trigger

Wrong, in the U.S., anything other than the hand crank will generally be prosecuted as possession of an unregistered class III weapon. 5 federal years, no parole.


I was wondering if it would be possible to replace the crank wheel on the side by a pulley that could be mounted in the grip of the gun

Possible, but I wouldn't advise it for a number of reasons (preceeding and following).


that would theoretically allow the trigger to be pulled at 1200 pulls per minute

The full auto version of the M-14 was abandoned by the U.S. military (and everyone else) because it was uncontrollable at that rate of fire.


How much force is required to rotate the crank

The most force is going to be "starting torque", running after it's started shouldn't be a problem. 300 watts would probably do it.


Electrically powered devices are illegal

In the U.S., powered devices will generally be treated as class III. A hand cranked Gatlin gun is not class III, a GE minigun is class III, even if you use pneumatics or a weedeater as an alternate means of operating it.



a pneumatic rotary actuator, maybe this would be a loop hole

No, see above.


I'm not sure this device are still legal

I'm pretty sure that would fall under "powered device".


It all depends on your location and local gun laws

True, although I can't imagine where a local gun law will not apply. In the U.S. it's a federal felony.


then what government could possibly impose that ? One can't be blamed for trying to help his disabled shooting buddy right

The BATFE will.


higher rpms would be nice, but since the GAT system multiplies every rotation by four, 100-300 rpm is all that's really necessary on the GAT-shaft, because most guns aren't going to surpass 1200 rounds per minute fired anyway. 1200 rpm = 20 bullets fired PER SECOND (imagine the bolt travel and recoil on some guns ). This would clear out even the biggest magazine/belt/box in seconds

True, but see the M-14 explanation above. A better rate of fire would be around 600. A better weapon weight would be approaching 20 lbs (see M-60).


However a stepper motor design would be far superior in the area of controllability to the 'basic' DC-motor design

True.

[Jacks Complete]

You won't require anything like a 300W motor! That's 25A at 12V.

Get yourself to an auto scrapyard, and blag or buy a Range Rover electric window motor. Huge amount of torque from the gearbox that is built in, runs on about 3 amps max, enough power to cut the head off a kid when installed as normal, but you will never stall it in this application. Cut off however many teeth from your main gear, and you should be good to go.

Overdrive it with 24 volts if you want a higher RoF.

The other way would be a simple spring driven motor with a winding toy. You wind the handle, then press the button and it hammers the trigger for you.

Whoever asked how much torque/force you need, it will depend on your gun and the trigger weight required for let-off, as well as the travel in it. I had a dream about a standard servo that could be clipped to a trigger guard and used to pull the trigger should someone invent a clever wireless system that would allow action at a distance. The servo arm was wired direct to the trigger, and the entire device could move fairly freely between the two anchoring points. Not going to be fast enough for this idea, though.

[john_smith]

A central locking door/trunk solenoid (like on old Holden Commodores/Opel Records, probably a shitload of other cars too) with a 555 multivibrator circuit perhaps?

[furdog]

I hope I have got the idea of this conversation right. If the discussion is about full auto weapons that can be fired by a electric motor. Would that be illegal?

Paragraphs are your friend

I would not try or attempt this for various safety reasons, but I once knew a guy who took a GAT trigger the kind with the turn handle. He took the handle off and attached a electric 12 volt dc motor to the trigger and then to a battery . He then somehow made it work like the touch sensitive flashlights you mount on a gun. Never less when he squeezed it went full auto! No idea how safe this is! I guess this would be illegal? If I am wrong on the conversation then I apologize.

[BlackFalcoN]

I hope I have got the idea of this conversation right. If the discussion is about full auto weapons that can be fired by a electric motor. Would that be illegal?

The idea is to take a semi-automatic weapon and create a setup which will recreate a super-fast finger-action motion by means of the push of a button.
Mechanically the weapon will be semi-automatic, but since the RoF will be much higher, the behaviour will resemble a full-auto.

This design can be realized electrically or pneumatically as described above.

The actual creation of this design would be illegal in most parts of the world, so there's no use in repeating that over and over.
(This idea is for theoretical discussion only and yada yada yada... :rolleyes:)
Only build it if your law allows it and you have the right paperwork done etc. :)

Full-auto on most heavier calibre weapons will result in lousy accuracy, but one can imagine tactical situations where accuracy would be of less importance and superior firerate would offer a great advantage...

Also, the full-auto setup mounted on a .22LR rimfire would greatly improve the lethality of such a weapon.
The recoil of a full-auto Ruger 10/22 for example would be very manageable. (effective full-auto fire would be limited to 75 ~ 100 yards, but in most CQB situations that would prove to be sufficient.)

[Tectonic]

It isn't used for real firearms, but there's a thing called the "Firestorm Crank" used for Paintbal Markers, that basically does the same thing as the "GAT Trigger Systerm". The Firestorm Crank is also a few dollars cheaper, I believe if you're a penny-pincher.

Though, I don't know if something made for Paintball would work on a real firearm, but of course redneck-engineering, or nigger-rigging could definitely play a role in getting it to work.

Firestorm Crank (http://www.specialopspaintball.com/shop/product_detail.asp?SKU=201+0014&BRAND=EQUALIZER)

GAT Trigger System (http://www.deltaforce.com/catalog/uniquetriggersystems.html)

[BlackFalcoN]

The cheapest I was able to find the GAT was 34.95$ after some googling around.

The Firestorm crank looks very similar in design and performs the same task as the GAT.
Since the triggerpull on a paintballmarker isn't that different from most firearms, it will provide a viable alternative for the GAT I think.

Not sure about the mounting clip that keeps the Firestorm unit clamped to the triggerguard, since it was designed for paintballmarkers.
But like you said, anyone should be able to fix that with some creative engineering. ;)

[Tectonic]

On my Tippmann 98 Custom (Paintball Marker) the trigger pull is 3lbs, but can be modified to be as light as a mouse-click by cutting the trigger return spring and bolt spring.

For Paintball, The Firestorm Crank mounts easily with two screws to the trigger guard. However, again, that make some some thought to get it to work on a firearm.

Someone should give it a shot!

[Eoin]

The simplest 'full auto' for a semi is to tie a piece of strong line to the cocking handle, providing that it travels with the breech block or the carrier; pass it back through a loop tied around the stock, behind the trigger, then forward to the trigger.

Adjust the line so that when the cocking handle is fully forward it has just pulled the trigger.
Thus every time the breech closes the trigger will be pulled.

Fire can be selective by having enough slack in the line so that 'full auto' only comes in when the hand is closed tightly against the stock.

This system works best when the loop behind the trigger is a fixed metal ring, but if it is desired to not alter the firearm in any way then use the line loop.

This system is probably illegal too but has the advantage of being quickly disengaged and then becomes only a couple of bits of fishing line tied around the stock

[BlackFalcoN]

It isn't used for real firearms, but there's a thing called the "Firestorm Crank" used for Paintball Markers, that basically does the same thing as the "GAT Trigger System". The Firestorm Crank is also a few dollars cheaper, I believe if you're a penny-pincher.

I've looked into the Firestorm Crank a bit deeper and here are my findings:

- The Firestorm is roughly the same in design as the GAT but has the added benefit that it's ambidextrous. The unit has mounting-points to the left and the right for the crank to be placed upon. This leaves one side unused by the crank and allows for a pulley to be attached to the unused side for our design.

- The Firestorm can be had for as much as 25$, where the cheapest I found the GAT is 35$ (every penny saved, counts ;) )

- The Firestorm comes in 4 versions: the FC 101, 102, 103 and 104
Model FC102 (Tippmann A5) is the most versatile for use on firearms as it's the most generic version of the four.
It fits most other paintball markers and will fit most firearm trigger-guards as well according to other sites.
Version 101,103 and 104 are less desired, because they are created to fit the double-trigger housings etc. of various Tippmann markers, and probably will require some reshaping/ redesigning to properly fit a firearm.

- The Firestorm doesn't mention anywhere the words "GUN","FIREARM", "WEAPON" etc, which can be a huge benefit for international orders which have to go through customs.
No problems should be expected on paintball-marker parts.
(where the order of firearm parts (terrorist devices :eek: [baahs sheepishly]) could raise a big red flag )
If questions do arise regarding the purchase of a 'gattling system', you can easily justify it since you're just going to use it on a paintball marker, right ? :p


If somebody has experience with the Firestorm, please post your comments in this thread.

[BeerWolf]

The simplest 'full auto' for a semi is to tie a piece of strong line to the cocking handle...This system is probably illegal too

The BATFE already ruled that shoelaces are machineguns in the USA.

Heres a copy of the ruling:
http://www.jpfo.org/shoestring.jpg

[Joat]

From the The National Firearms Act Title 26, United States Code INTERNAL REVENUE CODE
5845. Definitions
(b) Machinegun. -- The term "machinegun" means any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger. The term shall also include the frame or receiver of any such weapon, any part designed and intended solely and exclusively, or combination of parts designed and intended, for use in converting a weapon into a machinegun, and any combination of parts from which a machinegun can be assembled if such parts are in the possession or under the control of a person.
Basicly the way I read it if it acts like a machine gun it is a Machinegun.

In order to build anything defined as a Machinegun under this law if you are not a FFL SOT,(lots of paper work, finger prints on file and opening your business to the BATFE to search anytime they like.) you must fill out an application and pay the $200 making tax first. But all applications to make machine guns will be denied.

The closest thing to full auto that is legal that I know of is the Akins Accelerator™ there web site is:
http://www.firefaster.com/
All it does is let the receiver move back when fired so that when it moves forward again the trigger hits your finger and fires another shot.

Of course the law only applies to people in the USA and state laws could be more restrictive. I'm not a lawyer so don't take this as legal advice.

[w22shadow]

I have done some research on this subject myself. It makes much more sense on the 1919A4, IMO. It certainly is not legal though; the motor would be considered the "trigger" on any such device.

Links:
Emory Jones' "Crank Fire Adaptor"
http://img105.imageshack.us/img105/7942/20809dcp0003ez0.jpg
http://img154.imageshack.us/img154/14/20809dcp00061gb7.jpg

Videos:
1919A4 Gatling Crank Adaptor
http://rapidshare.de/files/30955539/1919A4_Gatling_Crank_Adapter.mpeg.html

'Allied Armament' Crankfire Systems Crankfire (Bottom of Page)
http://alliedarmament.homestead.com/1919A.html
(The video is 404. :( NBK)

Good luck, anyhow. :)

[Diabolique]

I encountered a spring device placed behind the trigger, in some of my older firearms catalogs, that kicked the trigger finger forward when the rifle fired. It resulted in one pull of the trigger by your finger for each shot fired. It may have become prohibited by the BATFE (their name keeps growing with every prohibition they take on).

[BeerWolf]

If you're going to put on external electrical devices to simulate FA fire, why not just put a solenoid on the trigger, instead of motors?

Perhaps you could go to the junkyard and find one of the solenoids on a carb'ed car that increases the idle for the A/C. They take 12VDC, and have a 1/2" throw at several pounds of push.

If you put a switch on the stock that was closed by the operating handle at the front of it's stroke, and hooked it in series with the solenoid, it ought to fire at cyclic rate.

(edited for a silly spelling error)

[Docca]

Perhaps you could go to the junkyard ... 12VDC, and have a 1/2" throw at several pounds of push.

If you put a switch on the stock that was closed by the operating handle at the front of it's stroke, and hooked it in series with the solenoid, it ought to fire at cyclic rate.

Illegalities aside, that's a very good idea.

What I'd like to point out is that you would need to trigger it with something that is just finishing its stroke after the bolt is locked.

The thing that people forget (or more likely never knew) when doing these sorts of experiments is that the bolt must be locked closed before the shell is fired. Otherwise you have an out of battery discharge (it's a bad thing, google it).

On many weapons, the operating handle would work - e.g. the M-14 / M1A; on some weapons you'd need to catch something else (bolt carrier) - e.g. M-16 / AR-15. Whatever you work off of, it had better not fire the round before the bolt is locked.

Weapons that operate by blowback are a different subject - I can't tell you much about them (sorry).