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What Is The Perfect AR-15 Barrel Length?

Talyn

Talyn

SAINT
Founding Member
As per the vid, there really is no perfect length. It all depends on what configuration you want, and that retaining velocity may be an important factor in your area.


One thing that wasn't mentioned was that you can have a 14.5/14.7 inch barrel legally (non-NFA) but it "must" have a muzzle device that's long enough and "permanently attached" that takes it to/or greater than the non-NFA length of 16.1".

That being said that's still shorter than a typical 16" AR since it has a muzzle device that actually makes the OAL longer than the 16.1" barrel itself.
 
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Bassbob said:
As far as the dwell time isn't it going to be the same if you have a 16" barrel or if you have a 14.5" barrel with a muzzle break that's 1.5" long ?
Click to expand...

The way I understand it dwell time is based on the different gas port lengths which the vid really didn't explain.

Dwell time
In a gas-operated automatic or semi-automatic firearm, the dwell time is the amount of time that the gas system is charged with high pressure. It is determined by the amount of barrel after the gas port; once the bullet passes the gas port, the amount of time it takes to get from the gas port to the muzzle is the amount of time the gas system is charged with high enough pressure to cycle the weapon.

But the shorter the gas system the harder the gun runs.

A 1.5" MD on a 14.5" barrel has nothing to do with the gas bled off for function. It just attentuates the flash based on my experience.
 
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Clint Smith of Thunder Ranch is one of the most experienced and respected AR-15 trainers in the country, and he swears that 20" is the ideal barrel length to get the best performance out of the platform. I respect Clint very much and have no reason to doubt his advice. That being said, a 16" barrel is fully capable of performing almost any task that the average AR-15 shooter is likely to attempt. My agency issued 16" AR's to officers during my LE career (primarily because they were easier to fit into a squad car rifle rack) and they flawlessly performed any training task we threw a them. I'm not sure what is issued to officers these days.
 
Barrel length has a part in dwell time. Here is a good article explaining it. It talks pistol up to rifle.

www.google.com

What is Dwell Time?

As a quick refresher, the gas port is a hole drilled into the barrel that allows some of the burned gunpowder’s gas to cycle back into the gun’s action. The gas is funneled into t…
www.google.com www.google.com
 
BangBang said:
Barrel length has a part in dwell time. Here is a good article explaining it. It talks pistol up to rifle.

www.google.com

What is Dwell Time?

As a quick refresher, the gas port is a hole drilled into the barrel that allows some of the burned gunpowder’s gas to cycle back into the gun’s action. The gas is funneled into t…
www.google.com www.google.com
Click to expand...


"In ARs, the dwell time really only matters from when the bullet passes the gas port to until it exits the muzzle."

That's what the guy in the video Talyn posted was saying. That's what prompted me to ask for clarification on whether or not a muzzle break or flash hider is essentially a barrel extension and if it effects dwell time.
 
Bassbob said:
"In ARs, the dwell time really only matters from when the bullet passes the gas port to until it exits the muzzle."

That's what the guy in the video Talyn posted was saying. That's what prompted me to ask for clarification on whether or not a muzzle break or flash hider is essentially a barrel extension and if it effects dwell time.
Click to expand...
Flash hiders & muzzle breaks, no.

Supressors, however...can and do effect dwell time (and velocity—increasing it, surprisingly). It's one of the reasons adjustable gas systems are nice on guns you’re going to run suppressed.
 
Bassbob said:
"In ARs, the dwell time really only matters from when the bullet passes the gas port to until it exits the muzzle."

That's what the guy in the video Talyn posted was saying. That's what prompted me to ask for clarification on whether or not a muzzle break or flash hider is essentially a barrel extension and if it effects dwell time.
Click to expand...

Like Hans said, Flash hiders, comps or breaks will do nothing as they are ported allowing the gas to exit. Running a suppressor is different, hence not having ports. That’s why I posted the link, I saw your post asking about barrel length vs dwell time. Tayln post had good points on it as well.
 
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