What is a reduced diameter tube used for versus an original tube?
A big part of building a semiautomatic version of a full automatic firearm is
making it so that it cannot be readily made to fire in full automatic mode. Of
course, anybody CAN convert anything into full automatic given machining and
welding skills and time, but the idea is to make it difficult, so that the home
tinkerer cannot achieve it with hand tools and an hour or two of time. A reduced
diameter receiver tube helps with this by not allowing a drop-in bolt from a
full auto kit to fit. The bolt used for the build must be reduced in diameter to
fit the undersized tube. So, if someone gets your home build and decides to
convert it to full auto by simply getting a second kit and swapping some parts,
namely the bolt, they will fail, as the bolt will not fit in your tube.
What is a blocking rail?
As mentioned in the above question, wherein a semiauto build of a full auto gun
cannot be readily convertible to full auto, some modifications will need to be
made. Ideally, a reduced diameter tube would be used. However, this is not
always the easiest option. This is where the blocking rail comes in. It is a
round or square, or even flat but wide, key that is permanently welded inside a
standard diameter tube, before it is final assembled, running along sufficient
length to ensure that an original, unmodified bolt from a full auto kit cannot
enter the receiver far enough to fire the cartridge in the chamber. Ideally, it
is physically in the way of part of the full auto mechanism that was in the
original design. The original bolt would have a slot cut along its length so
that it will fit over the rail and move fully forward in the receiver. If you
have the rail in the way, then the slot is cut through the important area, such
as the original sear notch. This way, a full auto bolt cannot be made to work at
all. As the receiver is assembled, the rail is too difficult to remove without
extensive damage, rendering the gun useless. The rail is also helpful in that it
physically blocks the full auto sear mechanism parts from reaching the bolt,
provided its in the way as it should be. Another benefit of the blocking rail is
that it can be used in almost any shape of receiver, it is not limited to tube
receivers.
What is a disconnector, and why do I need one?
A disconnector breaks the firing cycle by interrupting the connection between
the trigger and sear, i.e.., "disconnecting" the trigger. This keeps the gun from
firing again and again, without the need to pull the trigger for each shot. In a
system that would fail to fire again and again, it assures that the firing
mechanism is reset, so that when the trigger is released, it will be ready to
fire when the trigger is pulled again, eliminating the need to re-cock it
between shots.
The BATFE defines full automatic as the discharging of more than one shot per
pull of the trigger. Therefore, you need a disconnector to keep the gun from
being an illegally made full automatic weapon.
What is a reweld?
A reweld is when the parts of a demilled receiver are placed back together and
metal shims are used to recreate the original length of the receiver. Rewelds
can be legal provided that provisions are in place to prevent the re-insertion
of fully automatic parts prior to welding them back together. Rewelds are legal
because the demilled parts are not actually parts but legally scrap metal. Make
sure that any modifications to markings and provisions to prevent the
installation of fully automatic firing parts are done BEFORE you reweld ANY
previous firearm especially those that could be a select fire or fully automatic
weapon.
What is demilled?
The ATF publishes guidance on how to properly destroy weapons in order for them
to be no longer legally considered a firearm. These standards are considered the
minimally acceptable method for legally destroying a firearm. Once demilled,
weapons are often made into "parts kits" which may or may not come with the
components that were "destroyed" in the demilling process. Any weapon that has
not been demilled properly is subject to confiscation by the ATF at a minimum.
It has happened before where companies have shipped parts kits that were not
properly demilled.
What makes an smg build a pistol build?
The problem with most smgs are that they typically have barrels somewhere
between 6" and 11" in length. This is coupled with usually having a stock. The
stock adds greatly to the guns practical accuracy. The problem with a semiauto
conversion build is that in order to qualify as a rifle, which it would be
classified as since it has a stock, it must have a barrel with a minimum of 16"
in length. The other problem is that as a rifle, it falls under 18 U.S.C. Sec
922 (r). This law defines the importability and assembling of "no sporting"
rifles and shotguns. It further goes to say that in order to qualify as a US
made rifle, and avoid this law, it must have a minimum number of US made parts,
which are from a specific parts list given in the law. The other parts of the
gun do not count one way or the other. Many guns sold as kits are somewhat of
oddities here in the US, and little to no US parts are available. Between
attempting to find a 16" barrel, or permanently attaching something quite long
to the barrel to reach 16", and finding or making US replacement parts, a kit
can be difficult to complete and be legal. An alternative is to build the gun as
a pistol. It already has a short barrel, and usually is relatively short
overall. The smgs usually fire a pistol sized cartridge, so handling them
without a stock isn't a big deal. The best part is that 18 U.S.C. Sec 922 (r)
doesn't apply to pistols, so other than the parts required to convert the gun to
semiauto, no US made parts are needed.
However, the stock needs to be left out, as does the mounting hardware. It
cannot be readily possible to mount a/the stock to the weapon.
What is an "80% receiver"?
Legally, There is no such thing as a "80% receiver", in the eyes of the ATF, a
component is either a receiver/frame or it's not a receiver/frame. Manufacturers
either submit a sample to the ATF and they make a determination or they follow a
previously approved non-receiver component specification. In the hobby an "80%
receiver" is a partially completed receiver that may be transferred without
serial numbers or the use of an Federal Firearms License (FFL) because it has
not reached the point where it is legally a receiver. As soon as the component
does reach the point where it becomes a receiver it must be transferred in
accordance with federal law. This could be as simple as bending a flat piece of
metal into shape or drilling a few holes. One should assume that any change to
an "80% receiver" may make that component legally a receiver unless the ATF
rules otherwise.
What is 922(r)?
922(r) is the section of law (part of the GCA) that prohibits the import or
assembly of weapons that are "not suitable for sporting use" that have more than
10 imported parts. It is a violation of the law to assemble any weapon that
could not be imported under the "sporting use" clause. The ATF takes a very
liberal interpretation of the law, so that it would be advised that no one
should build an weapon using 10 or more of the imported parts listed in 27 CFR
478.39 without a letter from the ATF stating the weapon meets the definition of
"sporting use."
* (1) Frames, receivers, receiver castings, forgings or stampings
* (2) Barrels
* (3) Barrel extensions
* (4) Mounting blocks (trunnions)
* (5) Muzzle attachments
* (6) Bolts
* (7) Bolt carriers
* (8 ) Operating rods
* (9) Gas pistons
* (10) Trigger housings
* (11) Triggers
* (12) Hammers
* (13) Sears
* (14) Disconnectors
* (15) Buttstocks
* (16) Pistol grips
* (17) Forearms, handguards
* (18) Magazine bodies
* (19) Followers
* (20) Floorplates
922(r) compliant means that no more than 10 of these parts on a weapon are
imported.
What is NFA?
The NFA is the National Firearms Act, a 1934 law which provided for the
registration and taxing of certain weapons. This included Machine Guns, Short
Barreled Rifles, Short Barreled Shotguns, Silencers and other weapons.
(Basically everything EXCEPT handguns, rifles, and shotguns which have specific
legal descriptions.) Any weapon subject to this act must be transferred using
the appropriate ATF Form (a form 4 for non licensees, e.g. those without an FFL)
and have the appropriate tax paid prior to transfer. It is illegal to transfer
these weapons to another person without paying the tax and having an approved
form.
What is GCA?
The GCA is the Gun Control Act, a 1968 law which created the licensing scheme
that we operate under today. It also created a number of restrictions regarding
the transfer of firearms interstate and 18 USC 922 covers all the prohibited
acts under the GCA in general. The GCA also known as Chapter 44 of Title 18 has
been amended and changed over the years. Some of the changes have included the
FOPA (detailed below) and the expired assault weapons ban of 1994. If you are
looking for a federal law regarding firearms, it is likely in Chapter 44 of
Title 18. This includes 922(r)
What is FOPA?
The FOPA is the Firearm Owners Protection Act of 1986. In light of the abuses of
the GCA by government entities, congress passed this law that was initially
aimed at securing the rights gun owners and license holders. Like most laws, it
was perverted during the process and in the middle of the night an amendment was
added by the democrats which basically banned machine guns for all of us. Since
the number of legally transferable machine guns is essentially fixed the prices
have skyrocketed. It did, however, secure the right to travel anywhere in the
country with a firearm without fear of prosecution. For instance, it is legal,
to travel from Pennsylvania to Florida with your firearm even if you pass
through Washington D.C. provided your firearm is secured in the manner
prescribed by law. It also limited the ATF in the number of inspections that
could be conducted on compliant licensees.
Do I need serial numbers on a home built receiver?
No, you do not need to place any identifying marks on a home built receiver
unless you wish to transfer that weapon to another person at a later date or
register the weapon as an NFA firearm.
Can I build a machine gun?
No, you cannot. Exceptions exist, but if you are asking the question, more than
likely you're not the exception.
Is it legal to own a machine gun?
Absolutely legal, you must find one that was produced prior to 1986 and be
prepared to spend $200 for the transfer tax in addition to the price of the
weapon (expect it to be roughly 10x the cost of a semi-auto version of the same
weapon.) Other than the Form 4, there is no special license required on the
federal level for ownership of a machine gun.
Can I build a silencer, short barreled rifle, or short barreled shotgun?
Yes, but you must fill out and have in your possession an approved Form 1 from
the ATF before building, and you will pay $200 for the privilege.
Can I buy a silencer, short barreled rifle, or short barreled shotgun?
Yes, but you must fill out and have in your possession an approved Form 4 from
the ATF before you can acquire the weapon, and you will pay $200 for the
privilege.
What makes a gun F/A ?
First, F/A is an abbreviation for full auto, or full(y) automatic fire. The
BATFE defines this as a firearm that will discharge more than one shot by a
single pull of the trigger. Any more than one, it doesn't matter how many.
Basically, for the average person, full automatic fire is when the gun fires
itself after the shooter initiates the firing, and stops when the shooter
interrupts the shooting. By pulling the trigger, the gun fires, either because a
round is in the firing chamber and the action is cocked and ready for release,
or because, in an open bolt design, the bolt is cocked back, and releases to
chamber and fire a round. In either case, after the round is fired, the action
is operated. It opens and extracts the fired case, ejects it, and chambers a new
round, or, in the case of an open bolt design, the bolt is ready at the open
position to close once again, chambering and firing another round. In full
automatic fire, instead of stopping after the first round is fired and ejected,
the cycle continues, simply starting where it had originally started, firing
again. It will continue this cycle, firing, extracting and ejecting, chambering
and firing, until the trigger is released, the gun runs empty of rounds, or it
malfunctions.
In semiautomatic fire, the cycle is the same, except it is automatically
interrupted after each cycle. This is the job of the disconnector. Because of
this, the trigger must be released, and then pulled again, for each shot to be
discharged. In a closed bolt design, the firing itself is interrupted, so that a
new round is chambered, but not fired. In an open bolt design, the cycle will be
interrupted at the point where the bolt is held back, after ejection of the
empty case, ready to close, chamber and fire the next round.
It might be realized here that the open bolt design is quite simple, requiring
very few parts, as the bolt just moves back and forth, the firing pressure
pushing it back, and the recoil spring pushing it forward. All it needs is a
catch to keep the bolt back, and pulling the trigger releases it to go forward,
starting the firing cycle. The BATFE has realized this also. It is a rather
simple alteration to either deactivate or remove the disconnector, and the gun
will be a fully automatic weapon. Therefore, most open bolt designs are
considered to be fully automatic firearms to begin with. In most, if not just
about all, instances, the deactivation or removal of the disconnector in a
closed bolt design will render the gun a single shot, as it will not reset
itself and be ready to fire with another pull of the trigger. Also, it will not
continue to fire as a full automatic firearm.
The simplicity and inexpensiveness of manufacture leads to many of the
sub-machineguns that are cut up and sold as kits being of the open bolt design.
However, to be legal to make into semiautomatic firearms, they need to be
converted into closed bolt designs.