The Rise and Fall of the Submachine Gun

Quick Overview

Modern armies no longer use submachine guns as primary weapons because rifle technology advanced to offer intermediate cartridges with rifle power and submachine gun controllability, body armor negated pistol caliber effectiveness, and logistics favored ammunition standardization, rendering the SMG obsolete on the modern battlefield.

Key Points: The primary reason for the decline of the submachine gun is that rifle technology caught up, introducing intermediate cartridges like 7.62x39mm and 5.56 NATO that provided rifle range and accuracy with controllable burst fire rates, eliminating the need for pistol caliber automatics. Body armor advancements, specifically Kevlar and later rifle-stopping armor, nullified the effectiveness of pistol rounds (like 9mm or .45 ACP) fired by SMGs, as demonstrated by the US ditching the M3 Grease Gun in the 1990s. Logistical simplicity strongly favors standardization; adding an entirely different caliber of pistol ammunition for submachine guns complicates supply chains when armies prefer one family of weapons and ammo, as realized by the US in Vietnam favoring the 5.56 M16 over SMGs. Modern pistols have increased capacity, blurring the capability lines; for example, a modern Sig pistol can hold 20 rounds, which is two-thirds the capacity of a British Sten gun. The iconic MP5 saw use in counter-terrorist units because hostages often lacked body armor, but incidents like the 1997 North Hollywood shootout showed police bullets bouncing off armored bank robbers, highlighting the inadequacy of 9mm against modern protection. The submachine gun concept morphed into the Personal Defense Weapon (PDW) like the FN P90 or HK MP7, which fire small, high-velocity rounds capable of punching through armor, intended for vehicle crews, though PDWs remain niche, expensive, and haven't widely replaced carbines. The age of the submachine gun as a primary military weapon is over because the modern battlefield demands range, armor penetration, and logistics efficiency, all better provided by the assault rifle, leading most armies to issue cheaper, standardized carbines instead.