I'm confused about AR-15 barrel lengths.  Can someone tell me the length of the actual issue M4 barrel?  Is it possible to get an AR-15 with this same length barrel, or does it have to be longer?  Basically, I'm looking for the full low-down on what you can have and what's out there.  Thanks guys.

Well from what I understand a TRUE M4 has a 14.5 in. barrel. However anything under a 16in. barrel is illegal without a...class3 license(??). Someone more knowledgeable than me can tell you the specifics on what you have to do to acquire the license.

You could build what they call an m4gery which is basically an AR-15 with m4 feedramps, an A4 upper, collapsable stock so it's made to look just like the M4(except abviously without automatic fire). I think alot of people just use the 16in. light weight barrel so they don't have to get a liceanse for it.

Some of you other AR gurus please make sure I'm giving the right info here(I'm still learning stuff about the black rifle myself)

a real M4 barrel  has a 14.5 inch barrel.........if you want one like that you are going to have to pay a  200 bucks tax,  and do the paperwork for a short barrel rifle (form 1).  the minimium  legal length of any rifle barrel that does not violate the NFA rules, has to be 16 inches....which every manufaturer makes a 16 inch for their M4wannabe.

GOD DAMN  I am sick of hearing about class 3 licenses for SBR's, SBS's, silencers, machine gun'd, ETC....    you need a ONE TIME  $200 tax stamp.

The 14.5" M4+A2 flashhider is the military normal  for most.  You can get a 14.5" barrel with an Izzy/Vortex/Phantom pinned(welded) to meet the minium length without the additional $200 stamp.

Refer to the Full-Auto forum for more info... you either get your sheriff's signature or start a Corp. and a few months from now you can have all kinds of Class 3 goodies.

i was looking at getting a colt le6921 14.5" barrel. and i was willing to pay the 200.00 for the tax stamp. but then i found out if you want to stay legal, every time you go out of state with your weapon, you have to write a letter to the atf and request permission to take it, and that they said it could be a 4-8 week procees for approval. then when you come back home you need to write another letter to let them know your back. so i settled on the colt le6920. i am sure if this info is wrong someone will correct it.
            good luck
             catfish

Quoted: GOD DAMN  I am sick of hearing about class 3 licenses for SBR's, SBS's, silencers, machine gun'd, ETC....    you need a ONE TIME  $200 tax stamp.

Per gun, silencer, machine gun or destructive device. One stamp will not cover them all.

Quoted: The 14.5" M4+A2 flashhider is the military normal  for most.  You can get a 14.5" barrel with an Izzy/Vortex/Phantom pinned(welded) to meet the minium length without the additional $200 stamp.

I'm looking at the Bushmaster catalog and comparing the 14.5" Izzy M4s with the 16" Birdcage M4s.  The Birdcage M4 appears noticeably longer than the Izzy M4.  However, both list a "total barrel length" of 16".  That's a bit confusing.  Are you saying that the actual barrel on the Birdcage M4 is 16", plus another 1" (or thereabouts) for the removeable birdcage flash hider?  And that the entire barrel+Izzy flashider on the Izzy M4 is the part that is 16"?

Quoted: i was looking at getting a colt le6921 14.5" barrel. and i was willing to pay the 200.00 for the tax stamp. but then i found out if you want to stay legal, every time you go out of state with your weapon, you have to write a letter to the atf and request permission to take it, and that they said it could be a 4-8 week procees for approval. then when you come back home you need to write another letter to let them know your back. so i settled on the colt le6920. i am sure if this info is wrong someone will correct it.             good luck              catfish

get the 6921 barrel and just have the flash hider of your choice permanently pinned on.  

Okay, the military M4 has a 14.5 inch barrel.  this does not include the flash hider.  you do NOT measure your barrel with a flash hider or muzzle break attached, UNLESS it's part of the barrel (can't come off without cutting).

A civilian AR15 with M4 PROFILE barrel is a 16 inch barrel without the flash hider.

So what your looking at is 1.5 inches difference.  Because the flash hider SCREWS on the end of the barrel, you can't say the barrel is 14.5 and the flash hider is 1.5 and put it on and make it legal because about .5 or the barrel and flash hider overlap, AND you can always take the flash hider off to make it the original 14.5 inches.  This is why you have to use a longer flash hider and then get it pinned/welded on the 14.5 barrel.  with the 16 inch barrel however, your already at the legal length so you can attach anything you want to the end as long as it doesn't reduce the sound when fired.  

Remember that the 16 inch barrel is actually longer than 16 inches with something screwed on the end.

Thats the best i can come up with...

Quoted: I'm confused about AR-15 barrel lengths.  Can someone tell me the length of the actual issue M4 barrel?  Is it possible to get an AR-15 with this same length barrel, or does it have to be longer?  Basically, I'm looking for the full low-down on what you can have and what's out there.  Thanks guys.

Actual M4 has a 14.5" barrel.

Title I long arms that can be owned by civilians without special status from BATFE must meet the following criteria, by federal law.

rifled Barrel must be permanent 16" OAL not counting removable muzzle devices
shotgun barrel must be permanent 18" OAL not counting removable muzzle devices
rifles must be at least 26" overall length (with stock folded or collapsed if applicable)

So if you want to have an M4 type upper with a 14.5" barrel without special status, the barrel must have a permanently affixed muzzle device to bring to overall barrel length to 16" or longer. This means welding, threaded, blind-pinned and welded, or 1200 degree silver solder. Loctite, allen screws etc are not acceptable if the device is included in the legal length requirement.

If you want a barrel less than a permanent 16" length or rifle with OAL of less than 26", you must file a form 1 (if you manufacture) or a form 4 (if you purchase ready made) with the BATFE and pay a $200 one time tax stamp to register each weapon. That form and tax stamp is specific to that registered receiver and S/N until either you request to remove it from the NFA registry or the weapon is destroyed. If you qualify and the form is approved, the receiver is then registered as a title II weapon (SBR or short barrelled rifle) in the BATFE NFA registry. Then you can put a barrel(s)of the length(s) you specified on the form once it is approved and returned to you. You must also engrave or rollmark the receiver with the maker name and location, if you are the maker.

I did this SBR registration process for one of my Stag receivers, for an 11.5" barrel, took about 45 days on a corporate form 1. processing time can vary widely depending on your BATFE NFA branch examiner.

Worth it for me, not everyone wants to go that route.

Quoted: GOD DAMN  I am sick of hearing about class 3 licenses for SBR's, SBS's, silencers, machine gun'd, ETC....    you need a ONE TIME  $200 tax stamp.

Easy gunner...ya did noticed I put a question mark on that didn't ya?

OK I'm wanting to build the same thing I think. What Colt upper and lower do I need to build the newest one , what 14.5 barrel do I need to get.

1 Tax stamp per NFA item. CLEO signoff on each one, prints on each one and waiting on each one. The waiting is the hard part.... AND only if you live in a friendly state.

OK, so Bushmaster obviously developed the "welded on Izzy flash hider" so that people could have an AR-15 that basically is the same overall length as the real M4.  They just used the loophole in the law which states that the muzzle device can be considered part of the barrel length as long as it's permanently affixed.  Awesome...I'm liking that Izzy flash hider more and more each day.  

Quoted: OK, so Bushmaster obviously developed the "welded on Izzy flash hider" so that people could have an AR-15 that basically is the same overall length as the real M4.  They just used the loophole in the law which states that the muzzle device can be considered part of the barrel length as long as it's permanently affixed.  Awesome...I'm liking that Izzy flash hider more and more each day.

Bingo.
Not a loophole, they are just in compliance with the law.
You could weld a monkey wrench to the end of your barrel, as long as it brings it to permanent legal length, it's OK.

The primary draw back to a permanently fixed muzzle device is you can't clean you muzzle crown as thoroughly, and would be more difficult to change out the front sight base if you ever wanted to do that. Otherwise, no problem.