True barrel length question for those in “the know”!!!

[albritt]

ATF measures barrel length from tip of lands at muzzle to the face of chamber, that being said an OAL 20" barrel with a 2" chamber only has 18"s of lands and grooves.
So when all of "those in the know" start discussing proper barrel length to achieve proper powder burn to achieve maximum velocity in a certain round and say for instance a .308 needs a 20" barrel are they talkin 20" of lands and grooves or are they talkin a 20" barrel OAL?
or are some using ATF standards of measuring length and some measuring from lug to tip of barrel?

 

[MagMan]

Talking barrel OAL. From one end to the other.

 

[albritt]

Talking barrel OAL. From one end to the other.

That's what I call a "barrel length" just wasn't sure "everybody" is on the same page. So when someone is giving advice on barrel length when referring to FPS stats I can pretty much assume they are talking OAL correct?
Manufacturers differ on this measurement in some cases, at least Sako on some models I believe claim their barrel lengths from the front of the action to the tip of the barrel.

 

[albritt]

Thanks

 

[MagMan]

That's how I've always understood it. There are very few people that could actually figure out what the actual length from the lands to the muzzle is. Especially from a sporting goods store. On a barreled action you should be able to go from the vent hole to the muzzle and figure out where you are.

 

[FEENIX]

ATF Standard Method to Measure Barrel Lengths

This is ATF's standard method for measuring the length of gun barrels - it has been documented to be the case for shotguns and rifles.

Procedure

1. Unload the weapon.
2. Close the action.
3. Cock the action (this is important - unless cocked, the firing pin will protrude from the bolt face and may not provide the correct measurement.
4. Run a dowel or cleaning rod of approximately the bore diameter down the barrel.
5. When the rod is down as far as it will go, mark the spot where the barrel and permanently mounted attachments end on the rod. Screwed-on attachments do not count.
6. Measure the rod's length between the mark you just made and the end which you ran down the barrel.

 

[albritt]

ATF Standard Method to Measure Barrel Lengths

This is ATF's standard method for measuring the length of gun barrels - it has been documented to be the case for shotguns and rifles.

Procedure

1. Unload the weapon.
2. Close the action.
3. Cock the action (this is important - unless cocked, the firing pin will protrude from the bolt face and may not provide the correct measurement.
4. Run a dowel or cleaning rod of approximately the bore diameter down the barrel.
5. When the rod is down as far as it will go, mark the spot where the barrel and permanently mounted attachments end on the rod. Screwed-on attachments do not count.
6. Measure the rod's length between the mark you just made and the end which you ran down the barrel.

Correct way to measure

 

[albritt]

Using dowel for aol then subtract case length from dowel measurement is probly close enough to judge land and groove length

 

[albritt]

Or better yet rear of case to ogive!

 

[albritt]

Or better yet rear of case to ogive!

On a live round obviously.

 

[FEENIX]

Correct way to measure

Yes, but not when ordering custom barrels. Two different ways of measuring for different purposes.

 

[albritt]

Yes, but not when ordering custom barrels. Two different ways of measuring for different purposes.

As in?

 

[FEENIX]

As in?

You do not order barrels the way ATF measures.

 

[albritt]

Well sorta, I recently ordered a Criterion match .308 barrel for a compact Remage build that I wanted 18" + of lands and grooves so I ordered a 20" barrel. But yes I understand where your coming from, just originally wondered if that was the norm of thinking.