A test of the Sig Sauer M7, the replacement for the M4A1 in the United States Army

Three years ago, the United States Army announced the replacements for its M4A1 carbine and M249 light machine gun.

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In both cases, the winners were weapons from the German firm Sig Sauer: the XM5 and the XM250 (renamed M250 in May 2025). The former is a version of the Sig Sauer MCX Spear assault rifle, while the latter is a version of the Sig Sauer LMG light machine gun. The XM5 assault rifle has been renamed XM7 and finally M7 since May of this year.

One of the main new features of the M7 and M250 is that they incorporate the 6.8x51mm .277 Fury caliber, instead of the 5.56x45mm NATO caliber used by the M4A1 rifle and the M249 machine gun. The change in caliber aims for greater range and increased lethality.

Furthermore, this is hybrid ammunition that "uses a patented lightweight metallic case designed to handle pressures higher than conventional ammunition, resulting in dramatically increased velocity and on-target energy in lighter weapons", as noted by Sig Sauer in April 2022.

A few months ago, US Army Captain Braden Trent launched a scathing critique of the XM7, citing reliability issues, excessive barrel wear, and frequent breakage of key components. One of his criticisms concerned the weapon's combat weight, which includes the magazine and accessories used by soldiers: "The M4A1 comes in at around eight and a half pounds, which is somewhat lightweight, but still somewhat heavy compared to rifles of old. The XM7, by comparison, comes in at 15.4 pounds." These criticisms were made after Trent interviewed 150 soldiers from the 101st Airborne Division, the first unit to receive these new rifles, and after inspecting 23 XM7s already in service.

Although Sig Sauer responded strongly to those criticisms, in September the German firm presented an improved version of the M7 at the DSEI defense exhibition in London. This version reduced the weight of the XM7 by almost one kilogram, shortening the barrel, lightening some components, and incorporating a shorter SLX suppressor. You can see a series of images comparing both versions here.

Last Sunday, the YouTube channel Garand Thumb published a test with the improved M7 (in the video they call it the M7A1), commenting on the advantages and disadvantages of this weapon in relation to its predecessor, the M4A1:

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Main image: Garand Thumb.