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Posted: 1/5/2006 8:46:15 AM EDT
[Last Edit: 1/5/2006 8:55:26 AM EDT by glock47]
the atf rules say from end of barrel to breachface, minimum length for rifle 16", is this how AR15 barrels are measured?

Is the barrel extension, the part that the bolt locks into, part of the measurement of the 16"?

if the barrel extension is removed from the barrel is there still 16" of barrel on an AR15 barrel?

I plan to use an AR15 barrel on a different rifle, the barrel extension will not be used.

please help
Link Posted: 1/5/2006 8:58:15 AM EDT
The traditional way to measure muzzle to breechface is to drop a cleaning rod down a barrel and measure from the point where it hits the bolt/breech/etc., to the muzzle (not including any removeable muzzle attachment).

With an unassembled barrel you could measurer from where the locking lug cuts would be if the bolt was fully engaged.
Link Posted: 1/5/2006 9:45:14 AM EDT
good answer, thank you for your response. team member with 4000 posts, I believe you

from what you wrote, the barrel extension at the breach end does not count as part of the 16" of barrel,

I hope I got that right.

Link Posted: 1/5/2006 9:46:56 AM EDT

Originally Posted By glock47:

from what you wrote, the barrel extension at the breach end does not count as part of the 16" of barrel,




That is correct; the "breech face" will be where the face of the bolt is when locked in place with the action closed.
Link Posted: 1/5/2006 10:59:19 AM EDT
Damn. I've been getting accused up and down, left and right all week of being an idiot because i've got 3700 posts. I'm glad to see someone who can actually understand that a higher post count is or can at least be some reason to trust the advice given or the giver of the advice...



I've tried to convince guys that a $150 ACOG clone is probably junk but have been told I'm an idiot that spends all day putting "+1" after everyone else's posts...
Link Posted: 1/5/2006 11:08:40 AM EDT
flash hiders dont count unless their "welded"
Link Posted: 1/5/2006 12:16:50 PM EDT
NO, more correctly, muzzle devices don't count unless they are permanently attached. Welding a Flash Hider would be permanently mounting a muzzle device, but it doesn't have to be welding and it doesn't have to be a Flash Hider. Fake Silencers and Brakes count as muzzle devices and Silver Soldering with a MAPP torch works for the ATF.

Link Posted: 1/5/2006 6:36:02 PM EDT
When a cartridge is chambered in an AR-15, the case head protrudes about .125" from the breech of the actual barrel, although it is still inside the barrel extension. The face of the bolt when in battery comes to rest on the case head (with a .005" or so gap for headspace depending on the particular chamber). It is this point to the bare muzzle that is considered "barrel length."

http://home.comcast.net/~gocartmozart/chamber_with_case.jpg


As mentioned above by other members, with a cleaning rod in the barrel pressed against the face of the closed bolt, simply mark the point where the cleaning rod exits the bare muzzle, remove the rod from the barrel and measure this distance to obtain your "barrel length."
http://home.comcast.net/~gocartmozart/barrel_with_rod.jpg


Link Posted: 1/5/2006 7:10:49 PM EDT
I understand thank you

I needed the answer so I would not have to worry about buying a 16" ar barrel that would only be 16" on an AR15

Link Posted: 1/5/2006 11:45:43 PM EDT
[Last Edit: 1/5/2006 11:47:46 PM EDT by Randall_Rausch]
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