Recommended read that you can’t find anywhere else:
Classic M16 Armorer’s Manual :
Black Rifle M16 Retrospective:
Black Rifle 2 : M16 Retrospective:
Official GOV M16/M4 Classic Manual :
Operator’s M4/M16 Manual:
Chapters:
0:44 Velocity Per Inch Relationship
1:34 Diminishing Returns Curve
2:20 Twist Rate Explained
3:04 10.3 and 11.5 Short Barrels
3:34 Mark 18 Dwell Time Problem
4:51 Making a 10.3 Run Like an 11.5
5:30 The 14.5 and the M4
6:11 NFA and the $200 Tax Stamp
6:45 Pin and Weld Workaround
7:41 The 16 Inch Standard
9:02 Why 18 Inches Exists
9:39 Mark 12 SPR and Harmonics
10:48 The 20 Inch and the M16
12:05 Matching Gas Systems to Length
12:40 Reading Your Ejection Pattern
13:12 Short Barrels and Accuracy Myths
14:40 Which Barrel Length to Pick
Disclaimer:
This content is made for a general audience. Some details have been EXTREMELY condensed. For the full context, we encourage you to explore official data and records to draw your own conclusions.
Resources / Credits To
@Badassoptic
@DanielDefense
@ForgottenWeapons
@VortexNation
@GarandThumb
@AiirSource
@MountainsMulletsMerica
@operatorsanonymous
@TheUziButton
@precisionmachineshed
@FREEDOMEAGLE556
@Hoplopfheil
Brief Overview:
This video breaks down AR-15 barrel lengths and explains how barrel length changes velocity, reliability, and accuracy in a 5.56 rifle.
It walks through every common AR-15 barrel length from 10.3 inches up to 20 inches and shows what each one actually does. The core idea is the relationship between velocity per inch, the point where each added inch stops paying off, and what you actually use the gun for. It covers gas system pairing, twist rate, dwell time, the NFA rules that govern short barrels, and the myths people repeat online about short barrels being less accurate.
Content Creation
Content is researched through publicly available data via books, PDFs and websites. The content is completely restructured for storytelling purposes using PowerPoint style animation with AI assisted narration. For original research please visit the sources listed for this video.
Our videos are strictly for documentary, educational purposes only. Imitation or the use of any acts depicted in these videos is solely AT YOUR OWN RISK. Neither we nor YouTube are responsible for any injuries or damage to your guns if you try what’s shown in our videos. We are not a federally licensed gun store and DO NOT sell or transact with serialized firearms. We don’t sell guns and don’t teach how to change them in illegal ways (such as full auto trigger or any grey area NFA topics). By viewing or flagging this video you are acknowledging the above.
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For a velocity based round like 5.56 it absolutely makes a huge difference
Wonder what the difference is with my 28” barrel .22 compared to standard 20” .22
It’s a model 51c heavy
Your numbers can not be taken as gospel. Earlier this week tested the velocities of Frontier 5.56 55gr jhp from my 16" and 14" Bren 2s. The 16" yielded 3052 fps and the 14" 2883 fps as measured through my Magneto Speed, a difference of 169 fps.
What happens with .308 Winchester? Is it better the original length of the FN FAL barrel?
Don't know why I'm here. I don't care that much about gun and will likely just forget about the entire thing. But I still click to watch this.😅
When you get over 700 fps you can kill with a bullet.
When you get over 2400 fps, you get hydrostatic effects capable of knocking out a target.
Once you get over 3000 fps, you get crazy cavitation that guts a target, especially with ammo that breaks apart into the target like a green tip.
Also, faster is tighter and tighter is more accurate.
GREAT video!!! I’m versed on the topic. However, this vid CLEARLY explained the mechanics & physics AR barrels, gassing, and ballistics. Also, learned somethings, I didn’t know!!! Excellent job!!!🤘🏾💥🔫🇺🇸
A 20" barrel on a bull pup? Accurate. Hard hitting, reliable, maneuverable….
I chrono some 556 out of my 16 in barrel and it averaged 3041 fps
Thanks god we dont have those issues in Poland with barrel lenghts legality
What about RSAR or other short 556 variants. I think the hkg36c , sig 553 are still in use in other capacities in the world too
They haven't banned braces yet why are you saying on here they have thats what i took from it and do you not like the short Barrel I love it
I like the 10.5 inch barrel ar15 I'm meen come on most bad situations are gonna be up close and I don't care who you are getting shot with anything from any barrel length any caliber or how far you are from the target all of this will mess up your day so everything basically works at close range but it depends on what your wanting out of it you wanna hit something far away ya longer barrel great if im worrying about distance 18 inch barrel on a 308 ya baby 556 is a small round so coming from a small gun expected to be small In my head this is just my opinion ok please don't attack me over my opinion please I ask
I have a MK 18 and a 14.5 Windom Bushy ex Miami Townsphip PD patrol rifle , owned several 16in guns , always thought 14.5 was the sweetest spot
14.5 supremacy
20" gang!!!! I Chrono with a Garmin. I was getting 3296fps average with 55gr white box Winchester. Std dev of 20. Not bad for basic ball ammo.
Just the way Eugene had intended. (Aside from all the updates to the platform he never thought of.)
The jumping from meters to yards at 11:05 was a little confusing. Could you stick with one unit and put up conversion for the other?
Going to put together a rifle with a 12.5 inch barrel and mid length gas system. I intend to get an adjustable gas block.
Thanks!
Excellent video.🙏
I'm not in the US so both know little enough about the gun laws and shouldn't comment anyway. But isn't the point of the regulation of SBR's about their concealabity? Though adding 1.5" doesn't turn a 14.5" into a muzzleloader.😊
Tax stamps are free now