Gun Tools/Legal/Updated September 15, 2026
AR-15 Barrel Length and Overall Length Calculator: Rifle, SBR, Pistol or AOW
Enter barrel length, muzzle device and how the back end is configured, and see whether the build is a rifle, a short barreled rifle, a pistol or an AOW under federal law, with the barrels in stock at that length.
Quick answer
- A 16" barrel with a 1.7" removable muzzle device and a collapsible carbine stock (M4 type) is a rifle under federal law.
- Legal barrel length is 16" (a rifle needs 16"); overall length is 33.7" extended and 30.2" collapsed (a rifle needs 26"). 860 16" barrels are in the GunPartPicker catalog.
Source: GunPartPicker catalog and build data, prices checked September 15, 2026
Is my AR a rifle, an SBR, a pistol or an AOW?
Federal rules only: 16 inch barrel and 26 inch overall for a rifle, permanent devices count, stocks extended. State rules are linked below.
Bolt face to muzzle, before any device.
Length the device adds beyond the muzzle.
Measured on a Colt 6920: 16.1" barrel gives 32" collapsed and 35.5" extended.
Federal classification
Rifle. No NFA paperwork.
- Barrel measures 16" (16" minimum) and overall length is 33.7" (26" minimum).
- You are inside a twentieth of an inch of the line. Pinned devices should be measured to at least 16.1" so a warm barrel or a worn gauge cannot put you under.
- The 1.7" muzzle device is removable, so it counts toward neither barrel length nor overall length.
Legal barrel length
16"
device not counted
Overall, extended
33.7"
the federal measurement
Overall, collapsed
30.2"
what some states measure
Class
Rifle
has a stock
16" barrels in stock
Every AR barrel in the catalog at this length, in stock first. Match the gas system and thread with the buffer and muzzle thread tools.
Ranked by what builders add most, in stock first. One listing per model.
How the ATF measures barrel and overall length
Barrel length is measured from the face of the closed bolt to the muzzle. The ATF does it with a rod dropped down the bore until it stops on the bolt face, then marked at the muzzle. A muzzle device only counts if it is permanently attached: pinned and welded, blind pinned, or silver soldered at 1,100 degrees or more. Thread locker, crush washers and jam nuts do not count.
Overall length runs parallel to the bore from the muzzle to the rearmost point of the gun, stock extended if it collapses or folds. A rifle needs both a 16 inch barrel and a 26 inch overall length. Miss either one with a stock installed and it is a short barreled rifle.
A gun with no stock is a pistol at any barrel length, until a vertical foregrip goes on. Under 26 inches with a vertical grip it becomes an Any Other Weapon; over 26 inches it becomes a plain GCA "firearm", legal to build but no longer a pistol for carry purposes.
AR-15 overall length chart by barrel length: minimum rifle barrel length is 16 inches
| Barrel | Device | Back end | Result |
|---|---|---|---|
| 16" | A2, removable | Carbine stock | Rifle |
| 14.5" | 1.75" pinned and welded | Carbine stock | Rifle at 16.25" |
| 14.5" | A2, removable | Carbine stock | SBR |
| 11.5" | Any | Brace or bare tube | Pistol |
| 11.5" | Any | Carbine stock | SBR |
| 10.5" | Any | Bare tube, vertical foregrip | AOW |
| 16" | Any | Bare tube, vertical foregrip | Firearm (over 26") |
| 20" | A2 | Fixed A2 stock | Rifle |
Common barrel length mistakes
- Counting a removable device. A 14.5 inch barrel with a screwed on flash hider is 14.5 inches. It is a rifle only after the pin and weld.
- Pinning to exactly 16.0. Barrels are cut with tolerance and gauges wear. 16.1 inches or more is the practice.
- Putting the stock on first. A lower that has ever been a rifle cannot legally become a pistol. Build pistols from a virgin or pistol lower.
- The vertical grip on a pistol. Under 26 inches it is an AOW the moment the grip goes on. Angled grips and hand stops are the alternative.
- Trusting the collapsed measurement. Federal measurement is extended; some states measure collapsed. Check the state page before building near 26 inches.
Frequently Asked Questions
How is barrel length measured?
From the face of the closed bolt to the end of the muzzle, including any muzzle device that is permanently attached. The ATF measures it by dropping a rod down the bore against the closed bolt.
What counts as a permanently attached muzzle device?
Pinned and welded, blind pinned, or attached with high temperature silver solder. A crush washer, a shim, thread locker or a jam nut does not count, so the device adds nothing to legal barrel length.
Pin and weld 14.5: how long does the muzzle device need to be?
Measured, it must bring the total to 16 inches or more. Aim for 16.1 inches so a warm barrel, a worn gauge or a tolerance stack cannot put you under. A 1.5 inch device on a barrel that actually measures 14.5 gets you there with nothing to spare; most people use a 1.75 inch or longer device.
How is overall length measured?
Parallel to the bore, from the muzzle (including a permanent device) to the rearmost point of the gun, with a collapsible or folding stock in the extended position. Some states measure the shortest configuration, so the tool shows both.
What makes a build a short barreled rifle?
A stock plus a barrel under 16 inches, or a stock plus an overall length under 26 inches. Either one makes it an SBR, which needs an approved Form 1 or Form 4 before the stock goes on.
Can I put a vertical foregrip on an AR pistol?
Only if the overall length is 26 inches or more, at which point the gun is a GCA "firearm" rather than a pistol. Under 26 inches with a vertical grip it is an Any Other Weapon. Angled grips and hand stops avoid the question.
Are pistol braces legal?
Federally, a braced AR is treated as a pistol again after the 2023 brace rule was vacated in 2024. Several states regulate braced pistols or treat them as rifles. Check the state page before you build.
Cite this tool: GunPartPicker, “AR-15 Barrel Length and Overall Length Calculator: Rifle, SBR, Pistol or AOW”, https://gunpartpicker.net/tools/barrel-length-checker. Data from the GunPartPicker catalog and real community builds, prices checked September 15, 2026. Free to cite with attribution.
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