Complete AR-15 5.56 barrel length comparison from 10.5" to 20". Compare muzzle velocity, effective range, overall length, dwell time, and gas system compatibility to match your mission.
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The best AR-15 barrel length for most builders is 16": it clears the federal 16" rifle-barrel minimum without NFA paperwork, ran Magtech M193 at 3,086 fps in Lucky Gunner's chronograph test, and stays maneuverable enough for home defense. Choose 10.5-11.5" for CQB or vehicle use (pistol or SBR builds), 14.5" pinned and welded for the duty-rifle balance, or 18-20" only for precision past 400 yards. Compare common 5.56 lengths from 10.5" to 20" side by side below, then open the AR builder to spec a compatible gas system, handguard, and muzzle device.
Every inch of AR-15 barrel adds 5.56 velocity, but the gains flatten past 18 inches: across 16 loads, Lucky Gunner measured about 65 fps per inch from 10.5 to 14.5 inches, 35 fps per inch from 16 to 18, and only 11 fps per inch from 18 to 22. Magtech M193 runs 2,760 fps from a 10.5 inch barrel, 3,043 from a 14.5, 3,086 from a 16, and 3,183 from an 18. That is a 326 fps spread between 10.5 and 16 inches, which at 300 yards is the difference between 15.6 and 11.2 inches of drop from a 100-yard zero. The 16 inch barrel minimum, not the 26 inch overall length minimum, is the line that decides whether a stocked AR-15 is a rifle or an SBR: every length here clears 26 inches overall with the stock extended.
| Barrel | M193 velocity | Drop at 300 yd | Supersonic to | 75gr HD SBR expands to | OAL, stock extended | Federal status |
|---|---|---|---|---|---|---|
| 10.5" | 2,760 fps | 15.6 in | About 580 yd | About 110 yd | 29.0" | SBR with a stock; pistol with a brace |
| 11.5" | 2,831 fps (est.) | 14.5 in | About 600 yd | About 120 yd | 30.0" | SBR with a stock; pistol with a brace |
| 12.5" | 2,902 fps (est.) | 13.5 in | About 615 yd | About 135 yd (est.) | 31.0" | SBR with a stock; pistol with a brace |
| 14.5" | 3,043 fps | 11.7 in | About 650 yd | About 170 yd | 33.0" | Pin and weld a long device to 16"+, else SBR |
| 16" | 3,086 fps | 11.2 in | About 660 yd | About 180 yd | 34.5" | Rifle |
| 18" | 3,183 fps | 10.1 in | About 685 yd | Not measured | 36.5" | Rifle |
| 20" | 3,193 fps (est.) | 10.0 in | About 685 yd | Not measured | 38.5" | Rifle |
M193 velocities are Lucky Gunner Lounge chronograph averages for Magtech M193 from 10.5, 14.5, 16, 18, and 22 inch barrels (June 2026); 11.5, 12.5, and 20 inch figures are straight-line estimates between measured lengths. Drop and supersonic range are solved with the ballistics calculator engine at sea level and 59 F with a 2.5 inch sight height. Expansion range is where Hornady's 75gr InterLock HD SBR drops below the 1,900 fps it is designed to expand at, from measured muzzle velocities (Lucky Gunner and Hornady's 11.5 inch test barrel; 12.5 inch is an estimate). Overall length assumes a Magpul MOE stock fully extended and a bare muzzle; see it drawn to scale in the barrel length visualizer.
11.5 to 12.5 inch excels indoors and in vehicles. Expect higher port pressure, so plan for adjustable gas and suppressor-friendly parts. The velocity these barrels give up also shapes ammo choice, so pair them with a load from our best 5.56 ammo for short barrels guide.
13.7 to 14.5 inch keeps rifles compact while reaching the 16 inch barrel minimum with a pinned and welded muzzle device long enough that barrel plus device measures at least 16 inches (a 13.9 inch barrel needs a 2.1 inch or longer device such as a SureFire SOCOM brake; a 13.7 needs 2.3 inches or more). Great for duty or travel carbines that need flexibility.
16 to 20 inch pushes velocity and sight radius for Recce and SPR builds. Heavier but easier on parts and tuned for stability.
Match the length tier to the exact barrel. These are the direct picks for the debates that matter: 10.3 to 10.5 inch CQB, 11.5 to 12.5 inch compact SBR or pistol, 13.9 to 14.5 inch pin-and-weld, 16 inch non-NFA general purpose, and 18 inch SPR or precision.
Confirm pin-and-weld and NFA compliance before ordering. Prices are typical street prices and fluctuate.
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Barrel length cuts the terminal range of a 5.56 load far more than its hit range. From a 100-yard zero, M193 from a 10.5 inch barrel drops 15.6 inches at 300 yards against 11.2 from a 16 inch, and both stay supersonic past 580 yards, so a short barrel still hits at distance with the right hold. What shrinks is how far the bullet arrives fast enough to expand or fragment. Hornady's 75gr InterLock HD SBR is designed to expand down to 1,900 fps; it stays above that speed to about 110 yd from a 10.5 inch barrel, about 120 yd from an 11.5, about 170 yd from a 14.5, and about 180 yd from a 16.
The effective range of a 16 inch AR-15 is set by the load and the optic, not the barrel. M193 from a 16 drops 58.9 inches at 500 yards and is still above the transonic zone there, so a magnified optic with known holds reaches 500 yards. The 11.5 inch effective range question comes down to ammunition: a short barrel needs a bullet built to work at its lower impact velocity, which is what the best 5.56 ammo for short barrels picks are chosen for. Step through your own load and length in the velocity view of the barrel length visualizer.
Pick 16 inches for one do-everything rifle, 14.5 pinned and welded for a shorter duty carbine that is still not an SBR, and 11.5 for indoor, vehicle, and suppressed use as a pistol or SBR. A 14.5 gives up only 43 fps of M193 to a 16; an 11.5 gives up about 255 fps. Six jurisdictions still ban SBRs under state law, so check yours before buying a sub-16 inch upper for a stocked lower.
| Barrel | Best for | What you give up |
|---|---|---|
| 10.5" | The shortest practical 5.56 pistol or SBR for vehicles and tight rooms. | Lowest velocity (2,760 fps M193), the most blast, and only 3.5 inches of barrel past a carbine gas port. |
| 11.5" | Indoor, vehicle, and suppressed SBR or pistol builds; the most common short length. | About 255 fps vs a 16, and a shorter expansion range with any given load. |
| 12.5" | A compact general-purpose SBR with more dwell past the gas port than an 11.5. | Still a pistol or SBR under federal law, for a length only 2 inches short of a 14.5. |
| 14.5" pinned | A duty or truck carbine that measures 16 inches with an extended device pinned and welded. | The muzzle device is permanent; 43 fps behind a 16 with M193. |
| 16" | One rifle for home defense, training, and 500-yard shooting with no NFA paperwork. | The longest carbine package indoors and in vehicles, especially suppressed. |
| 18" | SPR and precision rifles shooting heavy match bullets past 400 yards. | Weight and length for 97 fps over a 16 with M193. |
| 20" | Rifle-length gas and maximum velocity for irons, service-rifle, and long-range builds. | The longest, heaviest option, with little velocity gained over an 18. |
Shopping for the barrel itself? The best AR-15 barrels guide ranks specific barrels at every length.
Five vetted 5.56 barrels covering every length tier from CQB to precision. For the direct barrel pick for your exact length (10.3 to 10.5 inch, 11.5 inch, 12.5 inch, 14.5 inch, 16 inch, 18 inch SPR), see the quick decision cards above. Pick the row that matches your mission, then pull the trigger on the build. For .300 Blackout short barrels, see the dedicated caliber guide; for long-range alternatives, compare these to 6.5 Creedmoor precision rifles. For premium carbon fiber options across both AR and bolt-action calibers, see our PROOF PXT barrel launch coverage. To see what each length does to drop and transonic range for your own load, follow the range simulator walkthrough.
Best 10.5 to 11.5 inch CQB or Pistol: lightest pencil profile for compact AR pistols and SBRs
Best Hanson Profile: mid-length option with included gas block
Best 14.5 inch Duty Carbine: chrome-lined .223 Wylde, mid-length gas
Best 16 inch General-Purpose: FN-made cold hammer forged, M4A1 manufacturing process
Best 16 inch Precision or Recce: .223 Wylde SPR contour with sub-MOA potential
Confirm pin-and-weld and NFA compliance before ordering. Prices reflect typical street price at OpticsPlanet and fluctuate.
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New barrel comparisons, velocity charts, and profile recommendations go to subscribers before the guide updates.
Move a one-meter panel downrange. Its size stays fixed; your sense of distance changes.
The target keeps its physical size as you change distance.
Trajectory from the point-mass engine with G1/G7 drag; barrel velocities from the load's published table.
Open the full range simulatorUse the visual bars to get a feel for how velocity, effective range, and overall length scale. Relative widths are normalized against the longest or fastest entry in the list. For the barrel we recommend for each specific length, see the quick decision cards above (right after the length-tier summary). To turn a barrel length into an actual drop chart for your load and zero, run it through the ballistics calculator, which adjusts preset velocities by barrel length.
Shortest practical 5.56 length: demands tuned gas but maximizes indoor and vehicle maneuverability.
Measured, -326 fps vs 16"
M193, sea level, 59 F.
Collapsed 25.7" · Extended 29.0" (MOE stock, bare muzzle)
Plan on heavier buffers, reduced-port gas blocks, and reliable magazines to keep cycling consistent, especially once suppressed. Expect premature wear, frequent parts breakage, unpleasant shooting experience, and poor terminal effect on target. 10.5 inch barrels are a compromise that sacrifices reliability and performance for compactness.
Ultra-compact package that keeps 5.56 terminal performance for close-in work when tuned correctly.
Estimate between measured lengths, -255 fps vs 16"
M193, sea level, 59 F.
Collapsed 26.7" · Extended 30.0" (MOE stock, bare muzzle)
Prioritize balanced buffer systems and gas port sizing to keep cyclic rate controllable, especially once suppressed.
Adds dwell time and velocity while staying maneuverable, earning a reputation as the modern compact sweet spot.
Estimate between measured lengths, -184 fps vs 16"
M193, sea level, 59 F.
Collapsed 27.7" · Extended 31.0" (MOE stock, bare muzzle)
Ideal for lightweight suppressor builds: balanced recoil impulse with H2 buffers or VLTOR A5 systems.
Popular pin-and-weld length that reaches a 16" measured barrel once a 2.1" or longer muzzle device is permanently attached.
Estimate between measured lengths, -85 fps vs 16"
M193, sea level, 59 F.
Collapsed 29.1" · Extended 32.4" (MOE stock, bare muzzle)
The modern standard for compact non-NFA builds. Needs a 2.1" or longer device pinned and welded, such as a SureFire SOCOM muzzle brake.
Service carbine baseline: battle proven and familiar, especially once permanently extended to 16 inch.
Measured, -43 fps vs 16"
M193, sea level, 59 F.
Collapsed 29.7" · Extended 33.0" (MOE stock, bare muzzle)
Mid-length gas with an appropriate port size keeps the action soft while supporting a wide ammo range.
Non-NFA legal minimum that delivers strong exterior ballistics and the broadest compatibility.
Measured, 16" baseline
M193, sea level, 59 F.
Collapsed 31.2" · Extended 34.5" (MOE stock, bare muzzle)
Baseline for most Recce builds; keeps Mk12 / SPR uppers within weight goals while working with common suppressors.
Stretch the carbine into SPR territory with increased velocity and sight radius for precision roles.
Measured, +97 fps vs 16"
M193, sea level, 59 F.
Collapsed 33.2" · Extended 36.5" (MOE stock, bare muzzle)
Ideal for Mk12-inspired builds: match the gas system to your ammunition to avoid short-stroking during cold weather.
Full-length rifle that maximizes velocity and dwell time for classic 5.56 performance.
Estimate between measured lengths, +107 fps vs 16"
M193, sea level, 59 F.
Collapsed 35.2" · Extended 38.5" (MOE stock, bare muzzle)
Best suited for rural properties or competition where velocity and stability matter more than compact storage.
Barrel length shows up downrange as muzzle velocity, drop, and how far the bullet stays supersonic. M193 is loaded at 300 yards: step through 10.5, 11.5, 14.5, 16, 18, and 20 inches and the table under the profile rewrites all three.
55 gr · G1 BC 0.243 · Standard military ball ammunition. High velocity, velocity-dependent fragmentation.
16" · 3,086 fps · measured
The rifle view measures the seated optic and sets this for you.
Velocity at target
1,991 fps
Muzzle 3,086 fps
Mach
1.78Supersonic
Path vs. line of sight
6.3 in low
2.0 MOA · 0.58 MRAD
Time of flight
364 ms
Energy
484 ft-lb
55 gr
Hold to center
Hold 2.0 MOA over
or dial 8 clicks up at 1/4 MOA (assumed)
Where the bullet slows
From 16 in, this load stays supersonic to 537 yd and drops below the speed of sound at 661 yd.
Barrel length at 300 yd
| Barrel (in) | Muzzle (fps) | Path vs. sight line (in) | Transonic from (yd) | Subsonic from (yd) |
|---|---|---|---|---|
| 8 | 2,476* | 18.1 low | 379 | 503 |
| 8.5 | 2,533* | 16.6 low | 395 | 519 |
| 9 | 2,590* | 15.2 low | 411 | 534 |
| 10.5 | 2,760 | 11.6 low | 456 | 579 |
| 11.5 | 2,831* | 10.3 low | 474 | 598 |
| 12.5 | 2,902* | 9.1 low | 492 | 616 |
| 14.5 | 3,043 | 6.9 low | 527 | 651 |
| 16 | 3,086 | 6.3 low | 537 | 661 |
| 18 | 3,183 | 5.1 low | 560 | 684 |
| 20 | 3,193* | 5.0 low | 562 | 686 |
| 22 | 3,202 | 4.9 low | 565 | 688 |
An asterisk marks a length between two measured barrels; its velocity is interpolated.
Trajectory from the point-mass engine with G1/G7 drag; barrel velocities from the load's published table.
Open the full range simulator
Always confirm local compliance steps (pin-and-weld, NFA paperwork) before ordering.
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Profile determines weight distribution, heat management, and harmonics. The wrong profile can turn a well-tuned length into a front-heavy, whippy mess that loses zero under sustained fire.
Thick behind the front sight base, thin elsewhere. This profile exists because the military needed to attach M203 grenade launchers to the barrel, a requirement most civilian builds don't share.
Government profiles made sense for Cold War doctrine. Modern barrels distribute mass better for accuracy and thermal stability.
Tapers from a thick chamber and gas journal toward a lighter muzzle. Shifts mass rearward while keeping the barrel stiff where pressure peaks.
Hanson and similar tapered profiles are the modern standard for builders who care about accuracy and balance. Worth the extra cost.
Uniform thin diameter from chamber to muzzle. Shaves weight aggressively while modern metallurgy keeps them surprisingly capable under heat.
Quality pencil barrels from Faxon, Criterion, or BA are accurate and reliable for general use. Unless you're running serious volume or sustained strings, the weight savings are worth it.
Looking for specific barrel recommendations? Check the Recommended barrels to explore section above for vetted profiles at each length, or jump straight to the best AR-15 barrels ranked for 2026 for buyer picks at every length tier.
Start with the environment. Tight interiors, vehicles, or suppressed-only use push you toward 11.5" to 13.7". Rural or open areas benefit from 16" and longer for velocity retention.
A 16"+ barrel, or a 14.5" with a long device pinned and welded, keeps a stocked AR-15 out of SBR status. Anything shorter is a pistol or an SBR; check state law first, since six jurisdictions ban SBRs outright.
Shorter barrels mean higher port pressure. Use adjustable blocks, appropriate buffer weights, and quality suppressors to manage cyclic rate, especially for 11.5" to 14.5" builds. Walk through the full process in our gas system and buffer tuning guide, then verify suppressor thread fitment against the suppressor compatibility guide before ordering a can.
Looking to translate these insights into a full build? Open the guided assistant to evaluate platforms, components, and compatibility notes tailored to your mission.
Building an AR pistol with a short barrel? The 26 inch overall length (OAL) threshold determines whether you can legally add a vertical foregrip without NFA paperwork.
Adding a vertical foregrip to an AR pistol under 26" overall length creates an "Any Other Weapon" (AOW) under the NFA. Since October 9, 2026, ATF does not enforce Form 1 approval or registration for AOWs, but the classification is unchanged and some states key on federal registration, so check state law before you install one.
If your AR pistol measures 26" or more overall, you can legally add a vertical foregrip. The ATF classifies this as a "firearm" rather than a pistol or AOW, so no tax stamp is required.
| Barrel | VFG Status | Notes |
|---|---|---|
| 10.5" | Borderline | Measure carefully. Use angled grip to be safe. |
| 11.5" | Usually clears | One more inch of margin than a 10.5; measure your own build. |
| 12.5" | More margin | Two inches more than a 10.5 on the same lower, brace, and muzzle. |
Overall length runs parallel to the bore from the end of the barrel or a permanently attached (pinned and welded) muzzle device to the rearmost point of the brace or buffer tube. Removable muzzle devices and suppressors do not count. To stay clear of the line, measure with any adjustable brace collapsed: a pistol that clears 26" in its shortest configuration clears it in every configuration.
Why 11.5" is more popular than 10.5": The extra inch of barrel ensures you comfortably clear the 26" threshold with most brace setups, allowing a vertical foregrip without NFA paperwork. For most shooters, the marginal velocity loss from 11.5" to 10.5" isn't worth the legal complexity.
You can shoot out a barrel in 10,000 rounds, or you can ruin it in 10 minutes with bad cleaning habits. The crown (where the bullet exits) is the final authority on accuracy, so protect it at all costs.
Jamming a rod down the muzzle end ("muzzle dipping") is the fastest way to nick the crown. Even a microscopic burr here lets gas escape unevenly as the bullet leaves, tipping it off axis and destroying your groups.
Always push dirt out the way the bullet goes: from the chamber out the front. Use a bore guide to keep the rod centered and prevent it from rubbing the throat, and use one-piece carbon fiber rods that won't pick up grit like coated steel.
Always clean from the chamber to the muzzle.
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Dwell is how long the bullet takes from the gas port to the muzzle. Port position sets two things at once: the pressure the port taps, and how much barrel is left past it.
Click to expand →
Avid shooter with 10+ years of experience including competition shooting, an associate member of the Professional Outdoor Media Association (POMA), and a member of the National Shooting Sports Foundation (NSSF) and Safari Club International (SCI). Built 10+ AR-pattern rifles and several handgun platforms for home defense, competition, and suppressed night shooting.
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Ready to continue? Here's the recommended next guide:
AR-15 gas system and buffer tuning guide with interactive calculators. Adjustable gas block setup, buffer weight chart (H1/H2/H3), ejection pattern diagnostics, and troubleshooting for suppressed and unsuppressed rifles.
Or explore a related topic:
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