Thompson SMG in 30 Carbine

Published on November 20, 2025
Duration: 1:10

This video details an experimental Thompson SMG chambered in .30 Carbine, a prototype submitted for the M1 Carbine trials. Despite resembling a Model 1928, its .30 Carbine chambering and longer magazine set it apart. The design aimed for minimal retooling but failed military requirements due to excessive weight (10-12 lbs unloaded), more than double the target. This specific unit, serial number 1, showcases standard Thompson controls and a proprietary magazine.

Quick Summary

An experimental Thompson SMG chambered in .30 Carbine was developed as a prototype for the M1 Carbine trials. Despite aiming for minimal retooling, it weighed 10-12 lbs unloaded, exceeding military requirements and leading to its rejection.

Chapters

  1. 00:00Intro: .30 Carbine Thompson Prototype
  2. 00:14Design Goals & Weight Problems
  3. 00:44Markings, Serial Number & Controls
  4. 00:57Magazine & M1 Carbine Trials Context

Frequently Asked Questions

What caliber is the experimental Thompson submachine gun featured?

The experimental Thompson submachine gun discussed is chambered in .30 Carbine. This caliber is a key distinguishing feature from standard Thompson models and was part of its submission for the M1 Carbine trials.

Why was the experimental .30 Carbine Thompson rejected by the military?

The prototype was rejected primarily due to its excessive weight. Unloaded, it weighed between 10 to 12 pounds, which was more than double the requirement set by the Ordnance Department for the M1 Carbine trials.

What is significant about the serial number of this experimental Thompson?

This specific experimental Thompson submachine gun is marked with serial number '1'. This indicates it was likely one of the very first prototypes produced for evaluation during the M1 Carbine trials.

What was the design goal behind the .30 Carbine Thompson prototype?

The primary design goal was to enable manufacturing with minimal retooling. This aimed to leverage existing Thompson production lines while adapting the platform for the .30 Carbine cartridge.

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