Minimum rifle barrel length (what defines a 'permanent muzzle attachment')?

[Njal Thorgeirsson]

Hello,

As I understand it, a permanent muzzle attachment adds to the legal length of the barrel. So a 14.5" AR barrel is still a non-SBR if it has a 1.5" flash hider.

But what is the legal definition of a 'permanent muzzle attachment'? Does it have to fully circle the muzzle? For example, could I weld a (mosin) bayonet onto a 6-inch mosin barrel?

Thanks!

 

[tyeo098]

Interesting question.

'Permanent' is defines as 4 equidistant tack welds, or a circumference weld.

The 'barrel' has to be 16+ inches, so a bayonet does not count as part of the barrel, and is not legal. Muzzle devices contain/redirect gases from the barrel and when welded on become part of the barrel. A bayonet does neither.

Not sure what the actual definition of 'muzzle device' is, but I'm pretty sure an ATF agent wouldn't find your setup funny.

 

[CoRoMo]

So a 14.5" AR barrel is still a non-SBR if it has a 1.5" flash hider.

Only if permanently attached.

But what is the legal definition of a 'permanent muzzle attachment'?

See the link and text that I copy/pasted below.

Does it have to fully circle the muzzle?

See the link and text that I copy/pasted below.

...could I weld a (mosin) bayonet onto a 6-inch mosin barrel?

Absolutely... but that would not suffice as a true extension/continuation of the barrel.

'Permanent' is defines as 4 equidistant tack welds, or a circumference weld.

Can you cite this?

Here's what the ATF's handbook says...

http://www.atf.gov/files/publications/download/p/atf-p-5320-8/atf-p-5320-8-chapter-2.pdf

2.1.3 Rifle.
A rifle is a firearm designed to be fired from the shoulder and designed to use the energy of an explosive in a fixed cartridge to fire only a single projectile through a rifled barrel for each single pull of the trigger. A rifle subject to the NFA has a barrel or barrels of less than 16 inches in length.

The ATF procedure for measuring barrel length is to measure from the closed bolt (or breech-face) to the furthermost end of the barrel or permanently attached muzzle device. Permanent methods of attachment include full-fusion gas or electric steel-seam welding, high-temp erature (1100°F) silver soldering, or blind pinning with the pin head welded over. Barrels are measured by inserting a dowel rod into the barrel until the rod stops against the bolt or breech-face. The rod is then marked at the furthermost end of the barrel or permanently attached muzzle device, withdrawn from the barrel, and measured.

Apparently, a blind welded pin suffices and happens to be the very 'least permanent' (most easily reversible) method known. It therefore, also might be the most popular/recommended method of permanent attachment.

 

[MErl]

CoRoMo, that really doesn't answer the permanently attached bayonet part. That is the really interesting question, what is the definition of a muzzle device.

Ok so ATF puts a dowel in the barrel and marks at the end. The end of what? The first point they can get a needle point sharpie to touch the dowel? The last point with a ring of metal completely circling the dowel? What about those twisted tuning fork flash hiders? Would a double bayonet with a spike above and below count? How about it it twists a little? At what point does a strike face become a bayonet?

 

[wildbilll]

Since the flash suppressors are of a larger diameter inside than the barrel itself, the length is obviously not measured reaching to a point down inside, it is the length that is even with the longest portion of the assembly, including the extension. I would say that the dowel length is that which, if a flat plate were attached to the end, would just touch the end of the assembly as the dowel finally reached the bolt face.

 

[Njal Thorgeirsson]

I mean the mosin bayonet does fully encircle the barrel at its attachment point. So the ATF definition of "permanent attachment" would be satisfied assuming it was properly pinned/welded. The document does not mention anything about the device fully encircling the barrel (with the exception of its attachment point). Thanks for the link CoRoMo! I think it pretty clear from that ATF document that they measure from the furthest point of the attached muzzle device (breech face to the tip of the bayonet). Additionally, the document makes no mention of required purpose- it doesn't say the device must redirect gas or anything like that.

 

[tyeo098]

Can you cite this?

http://www.titleii.com/bardwell/atf_letter40.txt

A seam weld extending at least one-half the
circumference of the barrel or four equidistant tack welds around
the circumference of the barrel are adequate for this purpose.

Some people are saying that in the 2007 revision this has been removed, but I have not seen the 2007 revision yet.

 

[rcmodel]

I think it pretty clear from that ATF document that they measure from the furthest point of the attached muzzle device (breech face to the tip of the bayonet).

I think it is pretty clear you will be jousting at windmills, and rooming with somebody named Bubba the Butt Bandit at the grey-bar motel, while praying for help.

Right after an ATF agent stuffs a cleaning rod down your less then 16" long barrel, to the end of the muzzle or muzzle device and measures it.

A welded on bayonet is not the end of the barrel, or a muzzle device at the muzzle, as they will most certainly measure it.

However, if you are that confident of your assessment of the FFA, you could be a test case.
It will make'ya famous!!

rc

 

[Njal Thorgeirsson]

I think it is pretty clear you will be jousting at windmills, and rooming with somebody named Bubba the Butt Bandit at the grey-bar motel, while praying for help.

Right after an ATF agent stuffs a cleaning rod down your less then 16" long barrel, to the end of the muzzle or muzzle device and measures it.

A welded on bayonet is not the end of the barrel, or a muzzle device at the muzzle, as they will most certainly measure it.

However, if you are that confident of your assessment of the FFA, you could be a test case.
It will make'ya famous!!

rc

Don't get me wrong- I certainly won't be trying this. It was simply a hypothetical legal question.

Again, the ATF document says "...marked at the furthermost end of the barrel or permanently attached muzzle device".

A flash hider or brake of any length certainly counts towards overall length. And like the flash hider, the bayonet would be welded to the muzzle and add to permanent overall length. So why would a long metal stick not be considered a 'muzzle device'?

 

[dogtown tom]

Njal Thorgeirsson .......So why would a long metal stick not be considered a 'muzzle device'?

Maybe because its a bayonet and has nothing do do with the muzzle other than being attached. It seems pretty self explanatory that a muzzle break or flash hider are "muzzle devices" due to their function and a bayonet is not.

 

[TaxPhd]

IANAL, but it would seem that the bayonet idea is accomplishing the same thing as Tac-Sol's SB-X barrel, i.e., a permanent muzzle attachment that serves no purpose other than lengthening a shorter than 16" barrel.

http://www.tacticalsol.com/tshome/category/ruger-rifles/ruger-rifle-accessories/ruger-rifle-barrel-upgrades

 

[CoRoMo]

http://www.titleii.com/bardwell/atf_letter40.txt

A seam weld extending at least one-half the
circumference of the barrel or four equidistant tack welds around
the circumference of the barrel are adequate for this purpose.

I note that the 1998 opinion letter does not indicate that those methods are minimum legal requirements, but are instead 'adequate' in their achievements. Other methods should also be 'adequate'.

Some people are saying that in the 2007 revision this has been removed, but I have not seen the 2007 revision yet.

The 2007 revision is irrelevant. The handbook that I linked to is from the April 2009 revision.

http://www.atf.gov/files/publications/download/p/atf-p-5320-8/atf-p-5320-8.pdf

But whatever, the 2007 revision reads as follows...

The length of the majority of rifle barrels is measured from the muzzle of the barrel to the face of the closed breech on a line parallel to the axis of the bore. In the case of a rifle having a chamber(s) not an integral part of the barrel, such as a revolving rifle, the barrel length is measured from the muzzle to the front of the separate cylinder and does not include the chamber. NOTE: Any muzzle attachment such as a flash suppressor, compensator, muzzle break, etc., is not included in the barrel length measurement unless the attachment is permanently affixed to the barrel. Acceptable methods for permanently attaching a device to a rifle barrel are deep penetrating, full fusion, gas or electric steel seam welds of high temperature silver solder. Depending on the dimensions of a particular barrel it may also be possible to permanently affix a muzzle attachment by drilling a blind hole through the attachment and into the barrel wall. A steel pin that is flush with or below the outside diameter of the attachment is then inserted and the hole welded closed.

Blind pinning was an acceptable method in 2007, but that's all been revised of course making blind pinning... still acceptable.

 

[tyeo098]

Welp, I stand corrected. Circumference weld it is.

 

[Colonel]

Ok so ATF puts a dowel in the barrel and marks at the end. The end of what? The first point they can get a needle point sharpie to touch the dowel? The last point with a ring of metal completely circling the dowel? What about those twisted tuning fork flash hiders? Would a double bayonet with a spike above and below count? How about it it twists a little? At what point does a strike face become a bayonet?

How many angels can dance on the head of a pin?

 

[deadin]

Could someone with a bad case of Parkinson's be considered an Auto Sear??

 

[RussellC]

Good grief! Just pay the 200 tax stamp and forget welding anything to it, is what I would do, or buy a 16 inch barrel. The bayonet idea is not compliant.

Russellc

 

[Colonel]

What about a permanently attached flash hider that also functioned as a bayonet (and Flux Capacitor)?

 

[Carl N. Brown]

My definition: "Permanent attachment" could be used as short hand for so well attached, the practical option for removal is a hacksaw (same as shortening a solid barrel).

(This is purely personal opinion and does not replace a letter from the ATF Firearms Technology Branch on the legality of a muzzle attachment as a barrel length enhancement.)

It is also my opinion that legal barrel length enhancement must be some sort of tube with a "muzzle" parallel to the bore, until I learn that ATF FTB says otherwise.

 

[Elkins45]

Interesting thought: one must do such work while the barrel is not attached to the receiver. If not one will be in possession of an illegal short barreled rifle, even if only temporarily.

 

[wally]

Apparently, a blind welded pin suffices and happens to be the very 'least permanent' (most easily reversible) method known. It therefore, also might be the most popular/recommended method of permanent attachment.

This is what FN did for the FS2000 to make the minimum OAL.

Use the search, other places on this forum, it has been claimed that 300 ft-lbs of torque on the muzzle device with the barrel fixed defines "permanent" if the issue actually comes up.