Howdy. It's just a generalization for the fact that many vehicle mounted weapons were considered an MMG because of a stable pintle or pivot mount that provided more accuracy, and many time the weapon was also equipped with a belt-fed ammo supply for a more sustained rate of fire than a hand-held LMG.
1. Change to an LMG: The UC often mounted a Bren LMG, which was still clip-fed -- so in that case consider the MMG to be an LMG.
2. Keep it as an MMG: Some UCs were outfitted with a Vickers MMG that replaced the Bren gun.
3. Other UC variants that saw service: * Boys ATR * 3" Mortar * "Wasp" Flamethower & fuel wagon * 2-pounder ATG (rear firing) * 6-pounder ATG (rear firing)
"God made Wizards, and God made Muggles - but Samuel Colt made them equal."
Im aware that the Carriers also carried other weapons, although the heavier mortars and the Vickers were carried and then deployed, rather than fired from the Carrier. The Boys was fired from n the vehicle. I thought thst the rating was possibly as you suggest to factor in the increased stability. What I'm trying to do is to look at how the Carriers of the Infantry Battalion's Carrier platoon were used. This seems to have been to work with the Infantry companies as very light arnour for scouting and especially in the attack to cross beaten ground to cover and rhen provide cover for the following infantry with their brens, boys and light mortars, although from what I read it seems that the drill was to deploy these weapons from the vehicles.
The principle role of the Carrier Platoon was to provide the infantry with the means to move a small number of men over exposed ground while under some degree of protection from enemy fire. This would allow them to reach a position where two of them, the commander and gunner, could dismount with the Bren and move into a firing position while the carrier withdrew to cover. The gun team would then lay down fire under which the riflemen of the Battalion could advance. In terms of organization the Carrier Platoon can be considered to have existed in three distinct forms; the original model of 1938, the expanded version of 1941-42 (itself modified in the desert campaigns) and the final variant of 1943-45. Under the 1938 establishment the Platoon consisted of a Headquarters with a single carrier for the Platoon commander, a Subaltern, who led three Sections of three carriers each. Aside from its 15-cwt truck, and two men who were attached from the Administrative Platoon, the Carrier Platoon effectively consisted of nothing more than its ten carriers and their three-man crews. The 1941 establishment made a number of important changes, chief of which was the addition of a fourth Section to bring the Platoon up to 13 carriers. Platoon Headquarters was expanded, the commander being promoted to a Captain and now assisted by a Subaltern. This was accompanied by the appearance of a Motorcycle Section. This looks to have been a development of post Dunkirk preparations by Home Forces for a possible German landing in the UK in late 1940, with Battalions directed to establish provisional Motorcycle Platoons for use in Home Defence.