Barrel question?

[blackoutbuild]

Ok, maybe a dumb question. I'm trying to decide what barrel length I need for my 300blk build. When I see a 7.5, 8, 8.5 barrel for sale, is the length quoted for sale, the measurement from the bolt face to the end of the barrel? I'm trying to get the right length barrel to where it does't protrude past the hand guard, I want the noveske pig to be tucked under the hand guard just a little bit. I see all these different pistol lengths advertised and I want to make sure how they measure the barrel before I screw up and order one that's too long.

[jryock]

From the NFA Handbook (ATF 5320-8)...
"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-temperature (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 The rod is then marked at the furthermost end of the barrel or permanently attached muzzle device, withdrawn from the barrel, and measured."

My 9-in barrel is 9 inches from the front of the upper receiver (where the handguard butts up to it, not the threaded part). Hope that helps.

[randyrucker]

I love that NFA handbook.

[ThreeHundredTraveler]

I love that NFA handbook.

I hate that the handbook even exists as a total infringement to the second amendment.

[jryock]

I love that NFA handbook.

I hate that the handbook even exists as a total infringement to the second amendment.

I hear you on that; the NFA should of been repealed the same time as prohibition. BUT, it is nice to have something to refer to for general questions, ATF practices, and a possible legal defense. Published precendence is good, and conflicting rulings are even better (if you are in a courtroom challenging the ruling).

[blackoutbuild]

From the NFA Handbook (ATF 5320-8)...
"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-temperature (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."

My 9-in barrel is 9 inches from the front of the upper receiver (where the handguard butts up to it, not the threaded part). Hope that helps.

So by the way I measured which is the ATF procedure your barrel would measure more like 8 inches. So when I order a barrel I don't need to measure from the bolt face, I need to measure from the front of he upper recieiver?

[jryock]

I'd have to run a cleaning rod down the barrel when I get home tonight to be sure, but I believe that the face of the bolt lines up with (or very close to) the front of the receiver. My upper is the factory AAC 9-inch MPW; the barrel sticks out about an inch further than the 8-inch KAC URX3.

I had a drawing of it somewhere, but damn if I can find it now.

[blackoutbuild]

I believe my bolt face is about even with the outside edge of the threads on my upper. Like you, I will have to check tonight when I get home. I just want to make sure I order the correct length barrel. Maybe some of the other members that have ordered a 9, or 8 or 8.5 barrel could measure their barrel with a rod down to the bolt face and compare that measurement with what they ordered and post it here, that would help me and others.

[dbod]

I have the mid-length diamond rails from YHM that are advertised as 9.3" paired with a 9.5" Core-15 barrel. The threaded portion of the barrel has about 3 threads protruding past the handguards.

[jryock]

Did some measuring and my AAC 9-inch upper…

Bolt face to tip of Blackout 51T = 10.8125 inches
Tip of Blackout 51T to muzzle = 1.6875 inches
Therefore, bolt face to muzzle = 9.1250 inches; and breech to muzzle = 9.0000 inches (bolt face to breech face is 0.1250 inch)

Upper receiver to tip of Blackout 51T = 10.6875 inches
Tip of Blackout 51T to muzzle = 1.6875 inches
Therefore, upper receiver to muzzle = 9.0000 inches

Conclusion, breech face to muzzle is what my barrel is measured from (9 inch), and the breech face is located at the end of the upper receiver (where the rail ends).