Before WW2 the Browning .50 machine gun changed from being water cooled to air cooled and was given a heavy barrel (HB) for ground roles to avoid overheating. The M2HB then, like today, had a rate of fire of about 500 rounds per minute (RPM). In the same period aircraft were strong enough to mount .50 calibre guns, but needed a lighter weapon with a higher rate of fire for air-to-air combat, leading to the much lighter AN/M2 version with a 750-850 RPM rate of fire, partly thanks to a light barrel. Overheating was avoided by airflow and cooler temperatures at altitude. During WW2 each version was used in its intended role in very large numbers.
Throughout WW2 the US worked on design changes to the AN/M2 to attain a rate of fire above 1,000 RPM, aircraft could only keep an enemy in their sights for a very short time so they needed a maximum density of shots to achieve hits and cause sufficient damage. After many failures due to very high numbers of stoppages and very, very short part life, they finally introduced a heavily modified version with a rate of fire of over 1,100 RPM, designated the M3. This model entered service in 1945, just before the end of WW2. Limited numbers were made, but it was later put back into production for a short time in the early 1950s during the Korean war. By then everyone else was using 20mm or larger canon for air-to-air combat.
From the 1960s US fighter aircraft also had 20mm canon, and the fast-firing .50 machine gun seemed obsolete. Then in the early 1980s FN Herstal started work on integrated weapon systems including gun pods for fixed and rotary wing aircraft. There were large stocks of new or almost new M3 guns in stores, the obvious solution was to use them. It was soon evident that M3 guns still had major issues with reliability and part life, so FN began work on solving them. Thanks to advances in metallurgy and heat treatment, and many design modifications the M3 was radically improved. The way was open for the design of reliable .50 calibre gun pods and later, pintle mounted systems. The improvement was so great that in 1989, when the US introduced the Avenger air defence system armed with Stinger missiles and an M3 machine gun, they did not use original M3s from their stocks, but bought the new FN® M3P (P stands for Machine Gun Pod) from FN Herstal.
Today FN Herstal manufactures both FN® M2 and FN® M3 models. Over the past decades both have been the subject of constant improvement. As an example, the FN SmartCore® shot counter was recently introduced to allow more efficient and cost effective small arms preventive maintenance and management. Today’s models are very different to their WW2 ancestors, and to similar-looking current competitors. They are in a class of their own.
The FN® M2HB-QCB is for the ground role. Recent enhancements feature a flash hider for improved combat effectiveness at night, along with a triple rail sight and accessory mounting. The FN® M2HB-QCB provides accurate fire against point targets, and sustained fire against area targets which led to the introduction of the quick-change barrel in the early 1980s. The maintenance at user and unit level is very basic. Its outstanding performance in combat means that this weapon will remain in service with nearly all major NATO and allied forces for many years.
The FN® M3 family is for use in airborne applications, in remotely operated weapon stations, and some land and sea pintle mounted roles. These missions require a high rate of fire for a maximum number of rounds to be fired with a short time-on-target. The light barrel and moving parts of the FN® M3 enable firing at steep downward or upward angles.
Both are champions with the same origin, but one is a sprinter and the other a weight-lifter.
