M1918 Browning automatic rifle
Colt's Manufacturing Company1917–1960Great War
Also known as BAR, Rifle, caliber .30, automatic, Browning, M1918, M1918A2
Image credit
- Title
- File:Army Heritage Museum B.A.R..jpg
- Author
- United States Army
- Licence
- Public domain
- Source
- https://commons.wikimedia.org/wiki/File:Army_Heritage_Museum_B.A.R..jpg
How Muzzle energy is calculated
E = ½ · m · v²
Inputs
- m11.66 g179.9 grverifiedsourcePublished as 180 gr; 1 gr = 0.06479891 g exactly.
- v823 m/s2,700 fpsverifiedMeasured with a 609.6 mm barrel, not this arm's 610 mm. Velocity outside the sourced range is not projected.
1 of 2 inputs link to their source.
How Muzzle velocity is calculated
nearest sourced barrel length — no extrapolation (SPEC.md §8.2)
Inputs
- v at 609.6 mm823 m/s2,700 fpsverifiedsourcePublished as 2,700 ft/s.
Assumptions
- This figure belongs to a 609.6 mm barrel. It is shown because it is the closest measurement that exists, not because it applies here.
1 of 1 inputs link to their source.
How Loaded mass is calculated
m_loaded = m_empty + m_magazine + n · m_cartridge
Not calculated: m_empty has no sourced figure yet. Nothing is substituted for a missing input.
Assumptions
- One magazine, filled to the stated capacity. Spare magazines, optics, slings and lights are the owner’s, not the arm’s.
1 of 4 inputs link to their source.
How Free recoil is calculated
E_recoil = ½ · m_firearm · v_recoil²
Not calculated: m_firearm has no sourced figure yet. Nothing is substituted for a missing input.
Assumptions
- Propellant gas momentum is excluded: ARMAG does not record charge weights (SPEC.md §14). This is therefore a lower bound on the real free recoil, consistent between entries but smaller than a figure that includes the gas term.
- Free recoil: the arm is unrestrained. Stock design, muzzle devices, stance and shooter mass are not modelled, because none of them is a property of the arm.
No input on this calculation carries a clickable source yet.
How Capacity is calculated
as published for the primary chambering
Inputs
- capacity20verifiedsourceDetachable box magazine; a 40-round magazine was issued for anti-aircraft use.
1 of 1 inputs link to their source.
Derived figures
Computed from the sourced values above. Open ƒ on any figure for the formula, its inputs, and the assumptions it makes.
How Momentum is calculated
p = m · v
Inputs
- m11.66 g179.9 grverifiedsourcePublished as 180 gr; 1 gr = 0.06479891 g exactly.
- v823 m/s2,700 fpsverifiedMeasured with a 609.6 mm barrel, not this arm's 610 mm. Velocity outside the sourced range is not projected.
1 of 2 inputs link to their source.
How Sectional density is calculated
SD = mass(gr) / (7000 · diameter(in)²)
Inputs
- mass11.66 g179.9 grverifiedsourcePublished as 180 gr; 1 gr = 0.06479891 g exactly.
- diameter7.85 mm0.3091 inverifiedsourceC.I.P. G1, maximum bullet diameter.
Assumptions
- Reported in the conventional lb/in² so it is directly comparable with published figures.
2 of 2 inputs link to their source.
How Power factor is calculated
PF = mass(gr) · velocity(fps) / 1000
Inputs
- mass11.66 g179.9 grverifiedsourcePublished as 180 gr; 1 gr = 0.06479891 g exactly.
- velocity823 m/s2,700 fpsverifiedMeasured with a 609.6 mm barrel, not this arm's 610 mm. Velocity outside the sourced range is not projected.
Assumptions
- A competition classification defined by the IPSC and USPSA rulebooks, stated in their units. It describes a scoring category, not an effect.
1 of 2 inputs link to their source.
How Magazine dump is calculated
t = (n − 1) / (rpm / 60)
Inputs
- n20verifiedsourceDetachable box magazine; a 40-round magazine was issued for anti-aircraft use.
- rpm575 rpmestimatedsourceThe article publishes 500–650 rounds/min for the M1918, M1922 and M1918A1, and two selectable rates for the M1918A2. Recorded as the midpoint of the first range.
Assumptions
- Cyclic rate held for the whole magazine, no stoppages, trigger held down. A theoretical figure for comparing mechanisms, not a measured one.
2 of 2 inputs link to their source.
How Sight error at 1 mm is calculated
θ = atan(misalignment / sight radius)
Not calculated: sight radius has no sourced figure yet. Nothing is substituted for a missing input.
Assumptions
- Shows what a stated aiming error costs. The misalignment is the reader’s figure; the site does not claim how well anyone aims.
No input on this calculation carries a clickable source yet.
Specifications
Every row here is generated from the schema, so a figure recorded on this entry cannot be missing from the table — and the same rows, read the same way, are what the comparison shows.
Identity
- Type
- Machine gun
- Action
- Self-loading
- Fire modes
- Semi-automatic
- Fully automatic
- Operating system
- Gas, long-stroke piston
- Designed in
- United States
- Produced in
- Introduced
- 1918
- Production
- 1917–1960
Dimensions and mass
- Mass, empty
- not recorded
- Magazine, empty
- not recorded
- Length
- not recorded
- Length, folded
- not recorded
- Width
- not recorded
- Height
- not recorded
- Barrel length
- 610 mm24.02 insource
Sights and rifling
- Sight radius
- not recorded
- Sight height over bore
- not recorded
- Rifling twist
- not recorded
- Twist direction
- not recorded
- Grooves
- not recorded
- Sight graduation
- 1,372 m1,500 ydsource
Published as sight adjustments from 100 to 1,500 yd; 1 yd = 0.9144 m exactly.
Operation
- Cyclic rate
The article publishes 500–650 rounds/min for the M1918, M1922 and M1918A1, and two selectable rates for the M1918A2. Recorded as the midpoint of the first range.
- Trigger pull
- not recorded
- Effective range
- not recorded
- Units produced
- 351,554source
M1918: 102,174 and M1918A2: 249,380, as broken down in the cited article.
- Launch price
- not recorded
Chamberings
- .30-06 Springfieldprimary20 rounds
Scale
A to-scale outline against family siblings. The dimensions are sourced; the shape is a representative outline for the type, and says so.
Representative outline — the dimensions are sourced, the shape is not. Overall length, and barrel length where recorded, are drawn from this entry's own figures; the profile is a generic one for the firearm type and says nothing about this arm's actual contours.
Not drawn: M1918 Browning automatic rifle (no sourced overall length).
Detail
Browning designed it in 1917 for a doctrine that did not survive contact with the trenches: walking fire, in which advancing infantry carried automatic rifles at the hip and sprayed the parapet as they crossed no man’s land. The idea was abandoned almost immediately. The rifle was not.
What it turned out to be instead was the first squad automatic weapon — one man in a section carrying something that could put sustained automatic fire on a target while the rest manoeuvred. It is a bad machine gun by later standards: the barrel does not change, so sustained fire ruins it, and twenty rounds of .30-06 in a detachable magazine is a short burst. It is nevertheless what the US Army used in that role for fifty-five years, and its absence of a belt is exactly why it was portable enough to matter.
The 1938 M1918A2 revision is telling. It removed the semi-automatic setting entirely and replaced it with two automatic rates, on the argument that a soldier issued this weapon should be laying down fire rather than picking targets — the opposite of the choice made for every rifle on this site.
This entry carries no weight and no overall length. The cited article publishes neither in its infobox, and its magazine-weight figures describe the magazine rather than the weapon.
References
This entry's own bibliography. Every citation key on this page resolves into this list.
- M1918 Browning automatic rifle · Wikipedia · 1363334542 · read 2026-08-31 · CC BY-SA 4.0
Last verified 2026-08-31 · review status: agent-populated