The entire Corps worked a number of miracles just in getting a force to Korea. From a standing start on July 7, they added personnel, packed their gear, loaded it aboard ship, sailed half way around the world, and fought three major actions (four if you want to count Inchon and Seoul as two) - all in five months. That's before you consider the weather conditions they faced at the Chosin.
No cold weather training, no cold weather lubricants, no time between operations for maintenance. It's a wonder anything worked (or lived through it).
Almost a decade before Chosin, the Marine Corps had fully committed to developing light infantry divisions - equipped with maximum heavy weapons. In 1950, a USMC division had 20% more men and 20% fewer trucks than an army infantry division. 2-1/2 times as many LMGs and over twice as many BARs as their army counterpart. Somebody has to carry the extra weight of those auto weapons and the additional ammo. Do you want the gunners, assistants, and ammo bearers to carry a carbine or a pistol?
Anyone who has ever been caught in a rain storm wishes he had brought an umbrella. Every piece of gear is a compromise. There's no way to calculate the lives saved by the extra 5 lbs. of MG ammo or mortar rounds carried by an ammo bearer who had a carbine instead of a Garand.
Since anecdotes are the coin of the realm here, how about one from the 1st Marine Division's Chosin report in a special section on cold weather operations:
It was reported that a number of the M1919A4 (air cooled) guns became relatively ineffective due to burned out barrels. Spares were not available in some cases because, due to the extra weight, gun crews were forced to abandon the spares during their arduous climbing about on precipitous terrain.
So an MG crew can't carry a spare barrel - part of its authorized equipment - but they can carry a heavier hand weapon?
No weapon performed normally in the impossible weather conditions; all types reported malfunctions. If the carbine was so bad, where is the official inquiry? Where is the revised T/O?