Question about machine guns.

[the naked prophet]

Okay, so I know the definition of a machine gun, according to the BATFE. A gun which fires more than one shot for a single pull of the trigger without manual reloading (or anything which could be easily converted into a machine gun, or any part which could convert a gun to be a machine gun).

I remember the "shoestring letter" in which the BATFE says a shoestring is a machine gun because you can pull the string and the gun pulls the trigger repeatedly, making the string the effective trigger.

But then there's the recoil stock for the Ruger 10/22 like was discussed earlier. Because you pull the trigger, and the stock just allows the gun to move back far enough to reset the trigger, you can fire very fast like full auto, without it being a machine gun.

But what about a device that you could install in your gun that would push the trigger forward when the gun was in battery? As in, you pull the trigger, the gun fires and cycles, and then pushes the trigger forward so your finger pulls the trigger again. Would that be a machine gun, in your opinion? I know that if I decide to build one, I should send a letter to the BATFE to see if they think it's a machine gun, seeing as it's them who'll burn down my house and whatnot if they think it is.

Any opinions?

 

[saltydog]

You mean:

What is needed is a (some link) or (some type of mechanism) between the bolt carrier (on return to the forward position) and the trigger --> to allow the trigger to return to the pull state.

Even though you keep full tension on the trigger, it should still be legal under the law as a (one shot) single pull of the trigger even though the bolt carrier (some link or mechanism) returns the trigger (at the right time) to the pull position. Thus trigger moves back by finger (firing weapon) and forward by link of some sort (return trigger to fire). Hence weapon will fire as fast as the carrier will allow!

So I guess the key is to return the trigger to firing position with the aid of a link or device using the carrier as the controlling element while maintaining finger presure to fire weapon?

 

[Roadwild17]

I believe theres something called a hellfire trigger system that may be of interst to you.

 

[The Drew]

I think you're gonna have a harder time making this work than having it pass initial ATF muster...

Bottom line is this, the BATFE makes up rules as it goes along... They interpret, and if they don't like your product, they'll declare it a machine gun or some other NFA item.

I suspect something similar for those 10/22 stocks eventually...

 

[saltydog]

I believe theres something called a hellfire trigger system

I think he is talking about a device internal to the weapon that returns the trigger to the firing position at the right time for the next pull. Not an auto sear as an auto sear works independently of the trigger thus classifying it as a machine gun.

 

[orangelo]

There is one called the Akins Accelerator. So far they seem to have BATFE approval but who knows how their decisions might change on a whim.

It is basically a stock that has a sliding action block that you attach the barreled action to. When the gun fires the entire action recoils backwards along with the trigger. After the recoil is over a spring pushes the entire action including trigger forward again. Your finger will still be in the same place and as the trigger/action is pushed against your finger it will fire again and repeat the whole process.

http://www.firefaster.com/faq.html

 

[Tyril]

This is a common application used in some paintball markers.

Most use a pneumatic ram that resets the trigger forward utilizing blowback gasses from the propellant charge.

http://www.pbreview.com/products/reviews/1812/

In practice, this means that the user merely has to put a constant pressure on the trigger, which reciprocates under the finger - firing the marker in a full-auto manner.

Pull harder, it shoots faster. Put too hard, and it only fires once. Takes a little getting used to, but fun in that application.

Ignoring legalities at the moment, it should be simple to create in a firearm with a gas-system. Simply route some of the gas into a regulator, and attach a piston. Timing would be difficult, but that's a tuning matter.

Before starting any such project, I would advise getting a letter from the BATF, stating that at this time, the device is either a firearm, or is not.



-mike

 

[Father Knows Best]

I could be wrong, but I seem to recall seeing a letter from BATFE stating that a trigger reset device that allows a firearm to continue firing as long as there is constant pressure on the trigger would render such a firearm a "machinegun" under the NFA, and installing one is therefore illegal.

 

[the naked prophet]

I certainly wasn't planning on starting any project without a letter from the BATFE.

I used to modify paintball guns, back in the day. I built reactive trigger (that's what tippmann called them) systems for my project stingray and then for some spyders. They worked okay. Not as well as the tippmann.

I was thinking more of a mechanical system, such as a linkage inside the body of an AK, with a "tab" that protrudes up and gets squeezed by the bolt carrier as it returns to battery, and as it gets squeezed it would push the trigger forward. It might need a beefier recoil spring though.

 

[saltydog]

I could be wrong, but I seem to recall seeing a letter from BATFE stating that a TRIGGER RESET DEVICE that allows a firearm to continue firing as long as there is constant pressure on the trigger would render such a firearm a "machinegun" under the NFA, and installing one is therefore illegal.

If you could provide a link to this BATF letter then the question will be answered.

 

[Father Knows Best]

Yeah, I know. I've looked, but can't find it. I may be thinking of the infamous shoestring letter, but something in the back of my mind tells me that the "trigger reset device" questions has been specifically addressed by ATF. I'll keep looking.

 

[MisterPX]

You can also use a rubber band, but you'd have to work on trigger pull pressure. What you want is the afore mentioned "response trigger" used in paintball guns.

 

[Low-Sci]

The Response Trigger is a decent idea, but it probably breaks the rules for legal semi-auto function.

What wouldn't is an electronic trigger. Paintball players use them, in tournaments, almost exclusively now. The idea is that the trigger pull is like a mouse-click, sometimes much lighter, and if you learn a technique with your fingers called drumming, you can fire ridiculously fast. Faster than a Response Trigger would let you shoot, probably, and without any air supply attached to the gun. Some tournament players can trip a trigger like this and fire easily over 10 shots per second. And its only semi-automatic. It would be completely legal, because the pressure on the trigger isn't constant. You still have to pull it once for every shot, but its so light and fast that it doesn't really matter.

 

[the naked prophet]

The problem with electronic triggers is that you end up pulling the trigger too fast. I used to work on custom boards for those too, by the way. An average player could fire around 8-10 shots a second with a mouse-click trigger in a normal firing position (although the average player estimated it at 15-20 shots per second ) and up to maybe 15 if he holds the gun in an awkward position (ie. not aiming, just going for maximum ROF). Using the drumming technique, experienced players could fire faster than the gun could cycle or the balls could feed - at first this would end up chopping balls in half. New circuit boards were invented that prevented the gun from firing if it wasn't completly ready to fire. But then you end up pulling the trigger once and firing, then pulling the trigger again just before it was ready to fire, then having to pull the trigger again, so you just pulled the trigger three times and fired twice. Although you can pull the trigger 25 times per second, the gun only fires 16 balls per second while it may be capable of 20.

This is where it gets complicated. The newer boards used "firing modes" or "buffers" so that if the trigger was pulled faster than the gun could cycle, it would buffer the "missed" trigger pulls and fire them as soon as the gun was able. Basically, the circuit board switched it to full auto mode as long as you kept pulling the trigger faster than a certain rate. That's how they really shoot that fast. I thought it was silly, and it was impossible to catch people cheating, especially with custom made boards that had "hidden" fire modes that the refs couldn't find. Last I remember before I switched to stock class paintball (pump action guns, 12 gram gas canisters (instead of 20 oz tanks, etc.), and horizontal gravity-feed 10 round tubes (aka "rock and cock" because you had to tilt the gun while pumping to feed a ball) they did away with the "no full-auto" rule at most places, and instead placed a bps cap of like 10-15 bps. That they could measure with acoustic equipment.

Anyway, my point is that an electronic trigger would be waaaaaay too easy to modify to full auto (like an open-bolt gun) and would get ruled a machine gun. Then, if you had circuit boards in your house, and a computer mouse, you could get charged with having the components to manufacture a machine gun

Not to mention that the trigger pull is the part of shooting most likely to throw off your shot. And concentrating on pulling the trigger as fast as you can is going to throw off your shot more than the recoil.

 

[Low-Sci]

Yeah, that's a good point. I realized that immediately after posting, I had forgotten about buffering. And then there's the whole "readily made or remade" problem.

On the other hand, if you put enough engineering into the feed system and the board to make it not-so-readily made or remade, you'd be in business.

And since bullets and cartridges aren't nearly so fragile as paintballs, it means you can use some hefty springs to slap them into place, something that you can't really do with paintballs, and that would eliminate a great number of those trigger overspeed issues. Belt-drive Halo loaders, warp feeds, and most recently the Q-Loader are all attempts at increasing the feed rate without brutalizing the paint.

I'm not saying it wouldn't be complex, and you'd still probably have to re-engineer the ergonomics of the rifle so you could shoot that fast and still aim the thing. But if you did it right, it'd definately be worth a shot.

 

[bamawrx]

Forget it. I have a design that does that very thing, and its very good. BUT, upon further review the ATF has a little thing they call the "cork test". You won't read about it anywhere, but its real. A forced reset will fail the cork test and will be considered a machine gun. PM me if you want more details.

 

[saltydog]

Forget it. I have a design that does that very thing, and its very good. BUT, upon further review the ATF has a little thing they call the "cork test". You won't read about it anywhere, but its real. A forced reset will fail the cork test and will be considered a machine gun. PM me if you want more details.

Well, there goes this thread. I saw some good ideas's here.