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The Colt Model 1925 Machine Rifle (better known as the R 75), R 75A and R 80 are lightweight American automatic rifles sold under the Colt Monitor name.[1]

Essentially an improved version of the Browning Automatic Rifle, the Monitor was essentially the culmination of Colt's work on improving the BAR after World War I. Sold from 1925 to about 1931, the Monitor was marketed to law enforcement agencies and some militaries, but failed to sell well in either regard.[2] The Monitors are quite similar to the FN Model D, another improved version of the Browning Automatic Rifle and are very similar in concept and improvements.


Colt, which held sales rights for the Browning Automatic Rifle in North America, South America and a few other countries, wanted to improve the design of said weapon; as such, the company went to work improving the design after World War I.[2]

The result of this would come to be known as the Colt Model 1925 Machine Rifle, better known as the R 75, the initial version of the weapon and the first to use the Monitor name. The R 75 would be joined by the R 80 in 1931, a model marketed towards law enforcement agencies.[2][1][3]

Both the R 75 and R 80 failed to achieve any significant sales. However, the R 80 was adopted by the Federal Bureau of Investigation (FBI) as their first (and only) official "fighting rifle", despite the company only purchasing about 90 R 80s in total. Another 20 or so R 80s went to other police agencies, but that was about as far as sales went. In total, only about 125 R 75s and R 80s were produced over its lifetime, with production discontinuing due to high costs of manufacture.[2][1]

One final iteration of the Monitor, the R 75A, was produced for the Netherlands Purchasing Commission from August to December 1942, with 832 produced, presumably to be sent into combat. The R 75A is regarded as the final iteration of the commercial Browning Automatic Rifle.[4]

Due to its rarity, the Monitor is one of the most sought after, if not the most sought after, variation of the Browning Automatic Rifle today. Most surviving examples are either museum pieces or are in private collections, with examples in particularly good condition fetching up to six figure sums.[3][5]

Design Details[]

Visually, the Monitors differ from the Browning Automatic Rifle with its use of a pistol grip, different compensator and different handguard. Internally, the Monitors are identical to the standard BAR.

All Monitors were assembled from commercial BAR receivers.[4] The weapon has a three position fire selector, with safe, semi-automatic and fully-automatic settings. The Monitors feature a wide wooden handguard which could give better protection to the shooter's hand.

The Monitors feature the same sights as early-WWI production BARs. Some Monitors, most prominently the R 75As, feature dust covers; most variants may feature dust covers that cover the ejection port, with the dust cover designed to open when the bolt is opened or closed. The R 75A features two dust covers; one for the ejection port and another used to cover the magazine well when not in use.

The most prominent part on the Monitors is the large compensator present on most of the rifles; the compensator is a Cutts-type compensator produced by Lyman Products Corporation[6] and is said to reduce the kick of the rifle, although it appears that the concussion from the compensator is rather intense. The compensator is not present on the R 75 and R 75A. Serial numbers for the R 75s and R 80s start at 100,000, while the serial numbers for the R 75A appear to be around 4300 to 5300.[2][4]


R 75

Original variant produced in 1925. Marketed towards military forces.

R 80

Law enforcement variant produced in 1931. Adopted by the FBI in 1933 as their official "fighting rifle".

R 75A

Improved variant of the R 75 with additional dust covers and a quick detach barrel.