A third IMBEL .40 S&W subgun prototype

Ronaldo Olive
by Ronaldo Olive

Following two earlier exploratory attempts to create a .40 S&W submachine gun ( http://www.thefirearmblog.com/blog/2017/07/12/early-40-sw-subgun-prototype-brazil/ and http://www.thefirearmblog.com/blog/2017/09/20/another-early-40-sw-subgun-prototype-imbel/ ) the research department of IMBEL’s Fábrica de Itajubá (Itajubá Factory, in Minas Gerais State) pushed their efforts one step further in the shape of a third prototype model, still under the general designation SMTR .40 IMBEL MD1. Captain Paulo Augusto Capetti Porto remained responsible for the project.

Captain Capetti's first (top) and second SMTR .40 IMBEL MD1 prototypes shared much of the general configuration, but the use of a polymer lower receiver was a major advance of the latter.

Although the new model kept the general configuration of the earlier prototype, including the use of the wire-type retractable stock, important changes were incorporated, this including an all-polymer lower receiver. In addition to that, the FAL-based firing mechanism was replaced with a new one, while the FAL pistol grip/trigger guard gave place to a reshaped configuration. This resulted in reducing the weapon’s empty weight from 3.2 to 2.7 kg, and would also lower manufacture costs if series production eventually came.

The gun clearly had a number of features to emphasize ambidextrous use, such as the vertical charging piece within the carry handle and fire selector (safe/semi/3-rd/auto) levers and ejection windows on both sides, the path of ejected cartridges being chosen through a quick change in the bolt’s position. The threaded barrel was 150mm long, and the gun’s overall length of 720mm was reduced to 500mm when the stock was retracted.

The IMBEL submachine gun fitted with a sound suppressor. The weapon's cyclic rate of fire was about 650 rounds per minute.

According to my scattered notes, three of these prototypes were completed in the early 2000s, but I only briefly met the first one “in person” for the two (shame on me!) photos used here. I know that they all worked pretty well in the severe in-house testing they were submitted to in anticipation for an eventual Brazilian Army certification test program, which never came. At a time when the .40 S&W round was entering the market as an answer to all requirements, the number of different cartridges abounded (frangible, JHP, FMJ, +P, Gold, etc.) and they were all used in the guns. Since they seemed to digest virtually everything, the Fábrica de Itajubá guys started using reloaded ammo with unjacketed bullets on a growing basis. Lead-fouling soon reached the barrel chamber of “Number 3” prototype, which resulted in headspace alterations and… KABOOM! Minor hand injuries for the hand of Captain Capetti… Research funds at that time were all but depleted, and the project then came to an end.

It would take about 17 years for IMBEL to decide to embark into another SMG project, which will soon be brought to your attention, TFB readers.

Higher-res pics? Yep: https://imgur.com/a/PVJ1x

Ronaldo Olive
Ronaldo Olive

Ronaldo is a long-time (starting in the 1960s) Brazilian writer on aviation, military, LE, and gun subjects, with articles published in local and international (UK, Switzerland, and U.S.) periodicals. His vast experience has made him a frequent guest lecturer and instructor in Brazil's armed and police forces.

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  • Baron of Livonia Baron of Livonia on Oct 07, 2017

    Great story Ronaldo. Always interesting to see what is happening in South American Country's.

  • James James on Oct 07, 2017

    Another great write up, Ronaldo. I'd love to shoot that thing.

    Moral: Use jacketed ammo and clean your barrel and chamber.