Trejo Machine Pistols: Mexican Pocket Machineguns

By J. M. Ramos

Deep in the heart of old Mexico lies a beautiful little town called Zacatlan. Surrounded by vast sweet apple orchards and dangerous deep canyons it is the ideal setting for a romantic or action-packed western movie. What’s more intriguing about this remote apple growing town is the fact that hidden deep within its orchards lies a gun factory, turning out not just ordinary semiautomatic pistols but also deadly pocket machineguns chambered for calibre .22 LR. In addition to producing pistols, the company also produced tortilla-making machines for local as well as for export market. Senior Gabriel Trejo founded the Armas Trejo S.A. factory. Along with his three sons, the company produced pistols from 1950 to about 1967. The total production of all models (semiautomatic and full-auto) was about 80,000. The production of full-auto models ceased in 1967. In 1971, the Mexican government closed all private factories producing weapons. The Trejo family however continued to produce their full line of tortilla-making machines.

The first production machine pistol was the Model -1 chambered for the economical .22 LR. Early production pistols did not bear any model designation on the slide. However, the later production pistols were marked Model -1 on the left side of the slide. The fire selector is mounted on the right upper side of the frame, just above the grip panel. This pistol was later produced in a semiautomatic-only version under the designation Trejo Model 1-A. About 1,263 of this variant were produced.

The second series of rimfire machine pistol produced by the company were offered in two versions, one with a floating chamber copied from the “Williams designed” Colt Service Ace and the other without this device. These pistols were designated as Model -2 Especial. The most noticeable feature of the Trejo Especial from the other models is the raised ventilated rib machined on top of the slide. On it, a well-designed fully-adjustable rear sight and matching target style front sight blade is mounted on top of the rib. Both sights are secured into their respective assembly grooves by small cross pins. Its overall format suggests that the Modelo Especial is basically a target model with selective-fire capability. The location of the fire selector is the same as the original Model -1. This pistol was also produced in a semiautomatic-only version. This is the most expensive among the Trejo produced pistols.

The third series of the Trejo pistol family is chambered for the more powerful .32 ACP (7,65mm) and .380 ACP (9mm Kurz). These guns, like their rimfire counterparts also operated from a conventional blowback system, sharing the same basic trigger mechanism, fire control and overall external format. This variation only fires semi-automatically. A single Patent Number 50921 covers all pistols. They exhibit excellent workmanship and fine finish.


The Trejo Model - 1 was a very small pistol externally resembling a Colt pocket automatic. It is blowback operated with a barrel bushing similar to that of the 1911 pistol. The barrel is locked into position by the slide stop pin. The manual safety and magazine release is also derived from Browning’s famous .45 ACP pistol. The brown plastic grips bear a medallion with the Trejo insignia and an apple. There is an ingenious sear-tripping mechanism located on the right rear upper side of the pistol consisting of a three-part linkage and a piano wire spring that enables the weapon to fire full-auto.

When the selector lever is placed on upper position “R,” the pistol fires “full auto” (“R” stands for RAFAGA which is full-auto in Spanish). When the selector is set in the lower position, it fires semiautomatic. The gun fires at an exceedingly high rate on full-auto due to its small calibre. It empties the 8-round magazine in less than half a second. 300 rounds of mixed ammunition were fired in this pistol without a single malfunction. In normal semiautomatic mode, the pistol can be easily fired at three rounds per second. The pistol consisted of 48 parts and has no magazine disconnector.


By removing the right side plastic grip panel, the hidden secret that allows the Trejo machine pistol the ability to provide a selective-fire capability is revealed. There are three main components that activate the automatic functioning of the pistol; namely the selector lever, the slide-activated tripper and the transfer lever which trips the hammer sear. A large wire spring forces the transfer lever downward away from the sear at all times.


With the fire selector set at full-auto “R,” its front hook will free the connection with the slide-activated tripping lever. In this mode, the front end of the trip lever will move upward underneath the edge of the slide while being pushed by the top end of the sear tripper (under spring tension). When the gun is fired, the slide will recoil to accomplish its usual function ejecting the fired shell, recocking the hammer and loading the next round to the chamber. As the slide starts to recoil, the upper front tip of the slide tripping lever will move upward (about 0.065-inch) on a corresponding hidden groove underneath the edge of the slide. This allows the rear end of the transfer lever (pushed downward by the long spring) to position itself just below the sear lug that extends outside the frame. As the slide returns to battery (trigger pull being maintained), the end of the slide groove will soon hit the front-end tip of the slide tripper forcing it downward. This will in turn push the top end of the transfer lever to rotate with its rear end extension hitting the sear lug which automatically trips the hammer as the slide comes to a full stop. This action will be repeated automatically while trigger pull is maintained or until magazine is empty. The slide will be held open after the last round is fired.


When the fire selector is set at the downward position, the pistol will fire semi-automatically. In this setting, the front hook of the fire selector will force the front end of slide trip lever to rotate downward below the slide. As the slide tripper is pushed downward, the top end of the transfer lever is also forced to rotate forward causing its rear end extension to move upward away from the sear’s external lug avoiding any contact during battery. The normal bar attached to the trigger positioned below the sear tripper does all the work in firing the gun along with its usual disconnector that is mounted vertically below the fire selector. The automatic tripping mechanism of the pistol remains inactive at this setting until the fire selector is once again pushed upward for full-auto firing. The overall arrangement is quite simple and straightforward. It worked perfectly. The mechanism of the Trejo machine pistol bears a strong influence from the earlier Spanish Star machine pistol with the exception that the fire selector is frame-mounted rather than slide-mounted as encountered on the Star. The trigger bar, disconnector and automatic tripping action, however, are nearly identical.

While it is difficult to understand the logic of marketing a pocket-size machinegun firing low-powered ammunition with minimum magazine capacity that can be emptied in a split second in full-auto, Senior Trejo may have envisioned that a weapon this small, capable of delivering multiple projectiles with one pull of the trigger, controllable enough to be fired with one hand, would have a devastating effect in breaking the morale of an adversary in a gun fight. If we take into consideration Mexico’s historical accounts in choosing weapons for combat be it urban or in the jungle, they always wanted the deadliest hardware available.

Unlike conventional submachine guns or assault rifles, the Trejo machine pistol is undoubtedly geared for a specialized application. It is aimed for those who wanted a unique concealable protection gun (where it is allowed) with the option of being able to have instant automatic fire in an extreme emergency. Another audience may have been the US machinegun collector market. Unfortunately, the Trejo full-autos were not allowed into the US, making it one of the most sought after production machine pistols in the collector’s circle.

(Ceased business in 1967)

Armas Trejo, S.A. DE C.V.
1A de Gomez Farias S-N
Apartado Postal No.4
Zacatlan, Pueblo


The author wishes to extend his special thanks to Jack V. Krcma, one of the world’s leading authorities in firearms. His invaluable assistance in supplementing photos and technical data as well as his test firing evaluations of the various Trejo models made the completion of this article accurate and complete.

This article first appeared in Small Arms Review V6N10 (July 2003)
and was posted online on November 1, 2013


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