Which barrel length is best for an AR-15? We perform the ultimate tests.

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Published 2023-07-09

All Comments (21)
  • @trevorm0329
    I've found 3 inches is a very effective and versatile length. Served me well for years
  • @georgelambo5145
    I think the main reason 13.7 exists is because of US firearms laws. 13.7 is the minimum you can pin and weld a good flash hider/muzzle brake while maintaining a rifle status.
    Also, this could have been a great collab between you and Paul Harrel, I mean he is the chrono master.
  • @drewminiard7896
    Love the dad advice at the end. In college, a friend told me something his dad told him along the same lines of what you said: “Don’t talk about it, be about it”. I’ve always carried that with me and glad to see it being spread to the masses.
  • @alaskanbas6507
    Very cool to see the actual performance in a direct comparison like this, makes me interested to see a similar test but for AR-10s
  • @bradbeam7254
    This is probably one of the most informative videos that you’ve put out (for me). With having the ability to get as accurate of data as possible gives great kudos to the GT teams wealth of contact, knowledge and experience! Your videos are out together very well and aren’t longer than they need to be while also entertaining. Very understandable why GT is the “best” channel on YT. Please keep it up and thank you.
  • @BlackdogADV
    I’ve used and owned them all. At the end of the day I prefer the 16” but 14.5” is nice also.
  • @dylan_lewis9309
    Great video, like that you used barrels from the same manufacturer and prod batch!

    Would have loved to see a 18 and 20 in this. I've been running my mk18 now for a few years and love it for the environment I'm in, heavy wood and hills, most of the time I can't see more than 200 meters unless in a valley with a pasture. I am going to pick up a long boi 5.56 next because I have more 5.56 cans than guns at the moment
  • @ChadHuey79
    They’re all good. The positive to the 13.7 is, it’s just long enough to be able to pin and weld a muzzle device on that makes it a legal 16 inches. It’s the perfect middle ground barrel for that application. Beyond that, the other length barrels are better suited for there specific purposes. I own a 16, 13.7, and a 10.5. I kind of want an 18, a 20, and either a 11.5 or 12.5 though too. Just for the heck of it. I like them all. Build your collection big and get good with all of them! Amen! Good video, keep up the good work! Thanks
  • @TomRolfson
    A job for every length, a length for every job. What was not mentioned was stretching-out a longer competition barrel, but then losing velocity at distance and then stepping-up to 7.62x51 and my opinion for any practical application other than plinking is everything >300yds. Quality rounds then go from poking holes to producing pink mist. (To clarify we're talking about big game or anything larger than a coyote.)
  • Wow, great video with incredibly useful information. My primary home defense rifle is my own build with a 14.5 YHM barrel with pinned/welded flash hider. After watching this I'm seriously considering doing a 10.3 build just because. Thanks for all you're doing. I just discovered your channel this week and have watched several videos. Lots more to go 😂
  • I love my 16 inch real steel Daniel defense v7. I compared it to my buddies short barrel, and the Daniel defense biggest bonus was that it wasn’t as stinky. It wasn’t something that was mentioned in this video but gas fumes released from the short barrel along with a much louder noise was just obnoxious to shoot. The 16 inch D7 is an absolute pleasure to be around. The short barrel is like hanging out with that loud obnoxious friend who drinks way too much at the bar.
  • @Synystr7
    I feel like not having the 20 inch, which is basically the control, is a shame.
  • @user-py9qi5xp8b
    This video was both educational and entertaining. Great job, GT. Next up you should do velocity and POI changes with various silencers!.
  • @monkeyfinger7949
    This was a really great comparison of these barrels. Excellent job on this video!
  • @youngloc216
    The deciding factor for me is this: as long as my barrel length allows the projectile I’m using to perform as designed and intended, I’m cool with it. Usually that means 16” and up. Usually, anything below, and you won’t get the dynamic wound channel or permanent wound cavity because at lower velocities, the round isn’t traveling fast enough to suck air into the channel behind it. You can see this amazingly well when shooting ballistic gel. The projectile, when traveling at adequate velocity, will suck air into the wound channel it causes, filling the space, and causing a small explosion inside of the wound channel when the channel rapidly closes, combusting the oxygen inside of the channel. This is a major, significant loss of performance and is the main criteria I employ when deciding barrel length. If it won’t cause that explosion in the cavity, I won’t use it.

    Would’ve been cool to perform these tests on ballistic gel and use the data to determine at what length and velocity you lose or gain that explosion in the wound cavity.
  • @jackmatthews5609
    I’d love to see this same set of tests performed on .308, 7.62x39, and 6.5creed.

    Also, why not include the 18 or 20”?
  • @Eddythebandkid
    It was cool to see Micah’s transformation from behind the camera to in front of the camera. Even his own channel is very cool to watch.
  • There’s no doubt for best performance: velocity and iron sight MOA value, it’s s 20 inch barrel. And that’s the one which properly supports the Mk262 round, which is ideal for midrange events. The factor to be most appreciated is when shooting Mk262 the shooter will get an MOA wind constant of 10 at 600 yards vs an MOA constant of about 7 from a 14.5 inch barrel. This essentially means better hits at distance in winds which cannot be accurately appraised, like 1-3 mph winds that are hard to observe. Creds: Military Rifle Instructor assisting the USAMU deliver SDM, TTT, and SAFS Training. Bottom-line is if hitting a distant (midrange) target is important then so is a 20 inch barrel. No interest in midrange, then any barrel length or just carry a pistol, it does not matter if you are a fantasy fighter. On the other hand if you are a hunter or someone pursuing marksmanship development the benefits of the 20 inch barrel are too important to be negated. One more thing, since the 20 inch barreled Rifle will get VLD bullets to the 1000 yard line , shooters who have an interest in becoming champion marksmen can take that rifle to the long line and really learn a lot about shooting since it takes more knowledge and skill to get good hits at long range with a Service Rifle than other platforms. In other words, if you learn how to get great scores at long range with an AR-15A2 or A4 you will undoubtedly shoot to High Master Classification with any other platform/caliber long range rifle out there.
  • Phenomenal info brother. Thank you. There’s so much heresy on the internet, it’s nice to see proof and testing done by an unbiased professional so we can all make our own individual decisions.