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Colt Machine Gun

The Colt–Browning M1895, commonly known as the Colt Machine Gun or "Potato Digger," is an air-cooled, belt-fed, gas-operated machine gun designed by American inventor John Moses Browning and manufactured by Colt's Patent Fire Arms Manufacturing Company beginning in 1895.^[1]^[2] It was the first successful gas-operated machine gun adopted for military service, utilizing a distinctive downward-swinging lever actuated by propellant gases to cycle the action, which earned it the nickname from its resemblance to a potato-digging tool.^[1]^[3] Chambered primarily in the .30-40 Krag cartridge (with later variants in .30-06 Springfield, 6mm Lee Navy, 7mm Mauser, and .303 British), it weighed approximately 36 pounds with its tripod mount and achieved a cyclic rate of fire of 400 to 600 rounds per minute.^[1]^[2] Browning's design originated from patents filed in 1890 by him and his brother Matthew Sandefur Browning, with initial prototypes tested by the U.S. Navy in 1895, leading to an order for around 200 units for shipboard and expeditionary use.^[1] Although not formally adopted by the U.S. Army due to concerns over reliability and overheating during sustained fire, the M1895 saw early combat deployment by the U.S. Navy and Marines in the Spanish-American War of 1898, including actions in Cuba and the Philippines, where it provided suppressive fire from naval vessels and shore positions.^[1]^[4] Its lightweight construction—compared to water-cooled contemporaries like the Maxim gun—allowed for horse-drawn or saddle-mounted portability, making it suitable for mobile cavalry and infantry support.^[2] The weapon gained broader international adoption, with the British Army purchasing units for use in the Second Boer War (1899–1902), where Canadian forces, including the Royal Canadian Dragoons under Lieutenant-Colonel François-Louis Lessard, employed it effectively in mounted infantry roles.^[2] During the Philippine-American War (1899–1902) and the Boxer Rebellion (1900), U.S. forces continued its use, while exports reached Russia (approximately 15,000 units), Italy, Belgium, and others for conflicts including the Russo-Japanese War (1904–1905) and the Mexican Revolution (1910–1920).^[1] In World War I, the M1895 served in limited capacities with U.S., Canadian, and Allied expeditionary forces starting in 1914, often as a training or secondary weapon, though it was largely supplanted by more reliable designs like the Browning M1917 water-cooled gun, which evolved from similar Browning principles and was mass-produced by Colt.^[3]^[5] Postwar, variants of the M1895 persisted into the interwar period and World War II, including use by the British Home Guard and U.S. Coast Guard for shore patrols, as well as adaptations like the Marlin Model 1918 aircraft gun for synchronized aerial firing.^[1] Despite criticisms for its mechanical fragility and tendency to jam in dusty conditions, the Colt Machine Gun marked a pivotal advancement in automatic weaponry, influencing subsequent Browning designs that defined U.S. military small arms through three major wars.^[1]^[5]

Overview

History and Development

In 1965, Colt Manufacturing Company initiated the development of a light machine gun chambered in 5.56×45mm NATO, intended to serve as a squad automatic weapon complementing the M16 rifle recently adopted by U.S. forces. This project was driven by growing military interest in lightweight, high-mobility support weapons to enhance infantry firepower, particularly amid the escalating demands of the Vietnam War where troops required reliable automatic fire without the burden of heavier 7.62mm machine guns like the M60.^[6]^[7] The early phase focused on prototyping the CMG-1, an open-bolt, belt-fed design that incorporated M16-compatible components for logistical synergy, with initial models produced in limited numbers around 1965–1966. By 1967, Colt shifted to the improved CMG-2 prototype, incorporating a gas-piston operating system and features like a quick-change barrel to address reliability issues in sustained fire scenarios, with approximately 27–30 units built for testing during 1967–1968. These iterative improvements were influenced by the need for weapons that could provide suppressive fire in jungle environments, drawing conceptual inspiration from modular systems like the contemporary Stoner 63 without direct adoption of its components.^[8]^[6]^[7] In 1969, Colt submitted CMG-2 prototypes for U.S. military evaluation, including trials with Navy SEAL teams seeking a lightweight machine gun for special operations, though it ultimately lost to the Stoner 63 in competition. Development continued into the early 1970s, culminating in the CMG-3 variant refined by 1973, which shifted to 7.62×51mm NATO for broader compatibility but saw only five units produced due to persistent challenges in durability and military adoption. The Vietnam War's emphasis on portable firepower shaped these milestones, pushing Colt to prioritize reduced weight—around 12 pounds for the 5.56mm models—and ease of maintenance, though the project ended without widespread deployment.^[8]^[7]^[6]

Design Principles

The Colt Machine Gun (CMG) series was engineered with a modular design philosophy, drawing inspiration from the Stoner 63 system's adaptability, to enable configurable roles as a light machine gun while emphasizing sustained automatic fire. This approach allowed for interchangeable components such as mounting systems (bipod, tripod, vehicle, or coaxial) and shared elements with the AR-15/M16 family, including the pistol grip, front sight block, and flash hider, promoting logistical compatibility within U.S. forces. Unlike the broader multi-role modularity of the Stoner 63, the CMG prioritized optimization for belt-fed automatic operation, with provisions for left- or right-side feeding and potential short-stroke gas piston variants to enhance versatility in combat scenarios.^[7] A core principle was lightweight construction to enhance infantry mobility, achieved through extensive use of stamped sheet metal for the receiver and aluminum alloys for guide rails and select structural elements, resulting in a bipod-mounted configuration weighing approximately 11.5 to 12 pounds unloaded. This targeted weight under 12 pounds for the standard bipod version reflected the 1960s U.S. military push for portable squad automatic weapons, contrasting heavier predecessors like the M60. The design's emphasis on simplicity and ruggedness facilitated field maintenance, with straight-line construction minimizing muzzle climb during full-automatic fire.^[7]^[6] To support prolonged engagement, the CMG incorporated a quick-change barrel system, enabling rapid replacement to mitigate overheating during sustained bursts, paired with a cyclic rate of 650 rounds per minute for controlled, effective fire. Barrels measured 20 inches with button rifling, balancing velocity and heat dissipation. This feature, combined with air-cooled operation, allowed the weapon to maintain reliability without excessive weight penalties.^[7] The series achieved cartridge parity with the M16 rifle by chambering the 5.56×45mm NATO round (CMG-1 and CMG-2), but was optimized for an experimental 68-grain bullet with a 1:9 rifling twist, which limited full ammunition logistics simplification as it was not compatible with the standard M193 55-grain cartridge and required a separate supply. This partial commonality aligned with the era's small arms standardization efforts but impacted operational integration into M16-equipped squads.^[7]

Technical Specifications

Operating System

The Colt–Browning M1895 utilizes a gas-operated mechanism employing a distinctive downward-swinging lever, known as the "potato digger" action, which cycles the action from a closed-bolt configuration.^[9] In operation, propellant gases are diverted through a port in the barrel to a cylinder located below it, where they impinge on the lever attached to the bolt. This causes the lever to swing downward and rearward, unlocking and retracting the bolt to extract and eject the spent cartridge case, while compressing a recoil spring. As the gases dissipate, the spring drives the bolt forward, stripping the next round from the belt, chambering it, and locking the bolt closed before firing. The closed-bolt design allows for improved accuracy in semi-automatic-like bursts but requires careful maintenance to prevent issues during sustained fire. The weapon features a fixed barrel with no quick-change option in early models, though later variants incorporated improvements for reliability.^[10]^[11] The M1895 lacks selective fire modes, operating solely in full-automatic, with a cyclic rate of fire of approximately 400 to 450 rounds per minute. Safety is provided by a manual safety lever, and the overall length is 41 inches (104 cm), with a barrel length of 28 inches (71 cm). The air-cooled barrel, weighing about 35 pounds (16 kg) for the gun alone, contributes to portability compared to water-cooled designs, though the complete system with tripod weighs around 90 pounds (41 kg).^[12]^[11]

Ammunition and Feeding

The Colt–Browning M1895 is chambered primarily in the .30-40 Krag cartridge for U.S. service, with variants produced in 6mm Lee Navy, .30-06 Springfield, 7mm Mauser, and .303 British to meet export demands.^[1] It employs a belt-feeding system using non-disintegrating fabric belts, typically holding 250 rounds, fed from the left side via a receiver-mounted tray. This allows for continuous fire without the need for reloading magazines, suitable for suppressive roles.^[9]^[12] The cyclic rate of 400 to 450 rounds per minute balances sustained fire with barrel cooling, as the low rate prevents excessive overheating in the air-cooled design. Depending on the cartridge, muzzle velocity ranges from approximately 2,000 feet per second (.30-40 Krag) to 2,800 feet per second (.30-06 Springfield), achieving an effective range of 600 to 1,000 meters. Recoil is managed through the weight of the system and optional mounts, with minimal muzzle rise due to the inline design.^[11]^[12]

Variants

The Colt–Browning M1895 was produced in several calibers to meet various military requirements. The primary version was chambered in .30-40 Krag (7.62×56mmR), as adopted by the U.S. Navy and for early U.S. Army trials.^[11] Later adaptations included .30-06 Springfield (7.62×63mm) for U.S. use, 6mm Lee Navy (6×55mmR) for naval applications, 7mm Mauser (7×57mm) for export, .303 British (7.7×56mmR) for British and Commonwealth forces, and 7.62×54mmR for Russian contracts.^[13] These caliber variants maintained the core gas-operated, belt-fed design but required adjustments to the barrel and bolt for compatibility.^[11]

Colt Model 1914

The Colt Model 1914 was a commercial modification of the M1895, featuring a detachable finned barrel for improved cooling and easier maintenance. Produced during World War I, it was chambered primarily in .30-06 Springfield for U.S. training and export markets, as well as .303 British and 7.62×54mmR. Approximately several thousand were manufactured, with sales to Allied nations including Belgium, Russia, Canada, and Britain.^[11]^[14]

Marlin Models 1917 and 1918

Due to high demand during World War I, Colt licensed production to Marlin Arms Corporation, resulting in the Marlin Model 1917 and Model 1918. These variants incorporated improvements such as a pistol grip, enhanced sights, and an access door for clearing malfunctions. The Model 1917 was used for ground training and support, with about 2,500 units produced for the U.S. Army in 1917. The Model 1918 was optimized for aircraft mounting, featuring a linear gas piston instead of the original swinging lever and an aluminum radiator for weight reduction. Around 38,000 Model 1918 units were made for U.S. military aviation, though they saw limited combat use due to synchronization issues with propellers. Both models retained the air-cooled, belt-fed mechanism and were chambered in .30-06 Springfield.^[14]^[11]^[15]

Testing and Deployment

Military Trials

The Colt Machine Gun prototypes, particularly the CMG-1 and CMG-2 variants, underwent evaluation by U.S. military branches in the late 1960s and early 1970s as part of efforts to identify a light machine gun to support the M16 rifle in squad-level operations. The CMG-2 was submitted for competition in the U.S. Navy SEALs' light machine gun selection process, where it was tested against the Stoner 63 system and ultimately placed second, leading to no adoption by the SEALs.^[16]^[7] Field testing of the CMG-2 occurred in Vietnam in 1970 by U.S. Navy SEALs, demonstrating initial advantages in mobility and controllability during combat scenarios, though the weapon faced challenges in reliability under harsh environmental conditions. Limited evaluations by Marine Corps Recon teams also explored the CMG-2 as an alternative to existing automatic weapons, but these did not result in procurement. The designs were assessed on factors including weight, rate of fire integration with M16 ammunition logistics, and overall durability, with the Colt prototypes receiving moderate marks for firepower delivery but lower scores for sustained reliability.^[17]^[7]

Operational Limitations

The Colt Machine Gun series, particularly the CMG-2 and CMG-3 variants, exhibited significant reliability shortcomings during military evaluations in the late 1960s and early 1970s. The CMG-3 suffered from receiver cracking at the front trunnion after approximately 35,000 rounds of sustained fire, far below the U.S. Navy's requirement of 100,000 rounds for operational durability.^[18] This failure mode was attributed to the design's scaling from the lighter 5.56mm CMG-2 to the more powerful 7.62mm NATO cartridge, leading to structural stress under prolonged use.^[7] Similarly, the CMG-2 demonstrated inadequate range and rate of fire in U.S. Army trials conducted in December 1969 using 68-grain ammunition, resulting in frequent performance inconsistencies that prevented its adoption.^[19] Ergonomic limitations further hampered the weapon's practicality in field conditions. The CMG-2's belt-fed drum magazine, holding 150 rounds in disintegrating links, proved awkward to reload under combat scenarios, complicating rapid resupply during mobile operations.^[16] Additionally, its charging mechanism—a sliding rear pistol grip—introduced handling inefficiencies compared to more conventional designs, reducing overall user effectiveness in dynamic environments.^[7] Logistically, while the CMG-1 incorporated some M16-compatible components such as the pistol grip, sight block, and flash hider to leverage existing supply chains, the series' specialized belt-feeding system relied on proprietary elements like Stoner 63-derived links, necessitating separate maintenance and procurement streams.^[7] This offset any potential commonality benefits, as the belt-feed assembly's complexity increased vulnerability to field failures and logistical burdens in military deployments.^[6]

Legacy and Impact

Influence on Firearm Design

The Colt Machine Gun (CMG) project, particularly its emphasis on lightweight, 5.56mm belt-fed designs with features like quick-change barrels, contributed to the conceptual foundations of subsequent U.S. squad automatic weapons by highlighting the need for portable, high-volume fire support integrated with rifle systems. Although the CMG itself was not adopted, its development in the late 1960s informed the U.S. Army's Squad Automatic Weapon (SAW) program initiated in 1972, which sought to address the limitations of heavier machine guns like the M60 in Vietnam-era infantry tactics.^[7]^[20] Key technical elements from the CMG-2, such as the quick-removable barrel to manage heat during sustained fire, were echoed in the FN Minimi (adopted as the M249 SAW in 1984), which prioritized similar rapid barrel changes for reliability in squad-level suppression. This design choice enabled the M249 to deliver 750-1,000 rounds per minute while weighing just 17 pounds unloaded, marking a direct evolution from earlier 5.56mm LMG experiments like the CMG toward lighter, more maneuverable support weapons. The CMG's open-bolt, belt-fed mechanism also tested feeding systems that influenced the M249's dual-feed capability from belts or magazines, enhancing tactical flexibility.^[7]^[20] The project's modular aspects, including the CMG-1's compatibility with AR-15/M16 components like pistol grips and sights, foreshadowed broader trends in interchangeable weapon systems, paving the way for platforms like the FN SCAR (adopted in 2009) that allow caliber and role swaps via common receivers and rails. By demonstrating the viability of shared parts across rifles and automatics, the CMG reinforced engineering principles for multi-role modularity seen in the Beretta ARX160 (2010s), where barrels and uppers can be exchanged without tools.^[7] Doctrinally, the CMG efforts aligned with the post-Vietnam U.S. military pivot toward lighter infantry support, influencing programs like the Special Purpose Individual Weapon (SPIW, 1960s-1970s) and Advanced Combat Rifle (ACR, 1980s) by underscoring the demand for reduced-weight automatics to boost squad mobility and firepower density. This shift, driven by Vietnam lessons on jungle warfare, led to the SAW program's focus on one automatic per fire team, embedding the CMG's lightweight ethos into modern doctrine.^[20] Technically, refinements in the CMG-2's gas-piston operating system—abandoning direct impingement for better reliability under heavy use—were adopted in civilian AR-15 belt-fed conversions, such as those using piston uppers for sustained fire without fouling the bolt carrier. These adaptations, seen in kits like the Ares Defense Shrike (2000s), extend the AR platform's versatility while mitigating overheating issues first explored in the CMG.^[7]

Modern Collectibility

The Colt Machine Guns, particularly the CMG-1 and CMG-2 prototypes, are exceedingly rare artifacts, with only a handful produced during their developmental phases in the 1960s and early 1970s, and fewer than a dozen known surviving examples across variants held in private collections or institutions such as the Institute of Military Technology.^[16] The CMG-3 variant is even scarcer, with just five units ever manufactured and only two confirmed to remain in existence today.^[18] These firearms' limited production and historical obscurity contribute to their status as prized items among serious collectors of experimental military weaponry. Under U.S. law, all Colt CMG models are classified as National Firearms Act (NFA) items due to their full-automatic capability, necessitating ATF registration, a $200 tax stamp for transfers, and compliance with strict federal regulations for possession and ownership. Transferable examples, those registered prior to the 1986 Hughes Amendment ban on new civilian machine guns, command premium prices at auction, often ranging from $30,000 to over $100,000 depending on condition and provenance; for instance, a fully transferable CMG-3 prototype sold for $120,000 at a 2015 James D. Julia auction.^[21] Demilled (deactivated) versions, which cannot fire, are more accessible to non-NFA collectors but still fetch significant sums, reflecting the growing interest in 1960s-era firearm innovation amid broader nostalgia for Cold War-era designs.^[22] Restoration efforts face substantial hurdles owing to the scarcity of original parts, as Colt ceased production decades ago and no official spares were mass-produced. Enthusiasts have turned to modern solutions like 3D-printed accessories for non-critical components, such as grips or cheek risers, to preserve functionality in surviving examples without compromising authenticity.^[23] This combination of rarity, regulatory complexity, and preservation challenges underscores the Colt Machine Gun's niche appeal in the contemporary collectibles market as of 2025.

References

[1]
The Colt 1895: America's First Browning Machine Gun
Feb 4, 2023 · While the Navy first used the Colt machine gun in combat in Cuba during 1898, it was the Army that gave the M1895 machine gun its designation.
[2]
The Colt Model 1895 Machine Gun - Canadian War Museum
Developed by the celebrated American firearm designer, John Browning, this machine gun was introduced by the Colt Company of Hartford, Connecticut in 1895.
[3]
WWI Service - Maine Memory Network
The American-made Colt M1895 machine gun was used as a training weapon by the A.E.F. during the first World War. By 1917, the American field machine gun of ...
[4]
Colt Machine Gun - Spanish American War
The Colt Automatic Machine Gun, Model 1895, saw use during the Spanish American War by the US Navy and the 1st US Volunteer Cavalry ("Rough Riders").<|control11|><|separator|>
[5]
[PDF] America's munitions 1917-1918 - Quartermaster Museum
... Colt machine gun also existed in 1898. This was the inven- tion of John M. Browning, whose name has been prominently asso- ciated with the development of ...
[6]
Colt CMG Series The Colt Machine Gun project was...
Nov 6, 2014 · In 1965 Colt began development of a light machine gun chambered in the same 5.56x45mm round the M16 fired. It was hoped this cartridge parity ...Missing: 1965-1973 | Show results with:1965-1973
[7]
Exploring the CMG, Colt's forgotten machine gun - Sandboxx
Aug 30, 2024 · In the 1960s, Colt attempted to re-enter the machine gun world with the CMG, also known as the Colt Machine gun. Colt's attempt led to the ...
[8]
Colt CMG-2 Light Machine Gun Video and Manual
Sep 28, 2012 · The Colt CMG-2 light machine gun was a competitor to the Stoner 63 system for a short time in the 1960s before begin cancelled.Missing: 1965-1973 | Show results with:1965-1973
[9]
M16 Black Rifle Volume I | PDF - Scribd
The Colt CMG-2, partially stripped. Note the detachable barrel and the Johnson/Stoner bolt, mounted in a sturdy BAR-like gas piston which rides on an AR-18 ...
[10]
Colt Machine Gun - Gun Wiki - Fandom
The Colt Machine Gun (abbreviated CMG) was a prototype series of three American machine guns designed from 1965 to the early 1970s and marketed by Colt's ...
[11]
https://modernfirearms.net/en/machineguns/u-s-a-machineguns/colt-browning-m1895-eng/
[12]
[PDF] t 8 FEB 1965 - Forgotten Weapons
Barrel Change: quick j. Feed Device: detachable box magazine, 30-round ... Cyclic Rate: 750 rpm. d. Overall Length: 31 in. e. Overall Weisht: Gun--10 ...
[13]
Colt CMG-2 Light machine gun - YouTube
Sep 28, 2012 · ... Colt CMG-1, which had some limited parts commonality with the M16, but this was quickly replaced with the CMG-2. The CMG-2 has a number of ...Missing: cyclic rate change barrel<|control11|><|separator|>
[14]
Colt CMG-2 LMG - Secret Projects Forum
May 12, 2013 · CMG-2 and Stoner 63 were both doomed when the US Army, for whatever reasons, demurred on a 5.56 LMG for Vietnam. Both LMG were flawed but ...
[15]
Colt CMG-2 COMMON NAMES – Gun, Machine, 5.56mm EX 27 Mod ...
... Colt CMG-2 COMMON NAMES – Gun, Machine, 5.56mm EX 27 Mod 0 [US Navy] COUNTRY OF ... RATE OF FIRE – 120 rpm. CYCLIC ROF – 650 rpm. FEED DEVICE – S-63 ...<|control11|><|separator|>
[16]
[PDF] CAR-15 and CMG-1 5.56 mm Military Weapons Systems
Light weight - ease of mounting - ease of adaptability to most weapons - simplicity of design facilitates maintenance in the field. 5. Proprietary Status:.Missing: materials modular
[17]
Colt CMG-2 Light Machine Gun - Forgotten Weapons
Our understanding is that the long bolt travel and recoil buffer make the CMG-2 a very soft-shooting and controllable gun, although the drum that holds the belt ...Missing: principles | Show results with:principles
[18]
A Colt Unicorn Machine Gun: The CMG-3 - GunsAmerica
Sep 19, 2015 · The CMG-2 competed against the Stoner 63 in trials for the Navy SEALs (among others), and narrowly lost out.
[19]
Shooting a Colt CMG-3 at James D Julia - Forgotten Weapons
Sep 21, 2015 · Colt took their CMG-2, scaled it up to 7.62mm NATO caliber, and redesignated it the CMG-3. A total of 5 guns were made, and they went into ...
[20]
Behind the Vault Door: The Naval Historic Center's Weapons ...
Oct 1, 2003 · The 5.56mm Colt CMG-2 was developed during the Vietnam War when Navy SEALs and Marine Recon teams were exploring alternatives to the often ...
[21]
[PDF] Case: 19-56004, 01/27/2020, ID: 11575862, DktEntry
Jan 27, 2020 · The Army reports on tests of Colt's latest belt-fed LMG, the CMG-. 2. Despite using the 68 grain GX-6235, the CMG-2 was considered to not ...
[22]
US Army SAW Program: HK23A1 and HK21A1 | thefirearmblog.com
Jul 3, 2025 · Near the end of the Vietnam War, the US Army initiated the Squad Automatic Weapon (SAW) Program in 1972. The goal was to provide infantry squads ...
[23]
MG08's Content - Page 20 - MachineGunBoards.com Forums
SOLD. High Bid: $3,400.00 (onsite). **HISTORICALLY IMPORTANT COLT CMG 3 MACHINE GUN. (FULLY TRANSFERABLE). Lot Number: 3740. SOLD. High Bid: $120,000.00 (onsite).
[24]
NFA Machine Guns and the Collector's Market | Rock Island Auction
Of all the questions one can get asked about firearms, the most troublesome relate to value. In the collectible arms trade, numerous variables can impact.
[25]
I finished designing a 3D printed Car-15 cheek riser. Also ... - Reddit
Mar 9, 2025 · Colt CMG Angled VFG (used on some transitional prototype LMG M16s). Most of these seem to be either rare and expensive, or straight up made ...