In the case of North Vietnam, I feel that it would be appropriate to get an overall look at where the Viet Minh got their weapons from and what those weapons actually were during the early days of its organization through the French Indochina War and up to the Vietnam War.

1945 - 1950

The Viet Minh had been collecting arms since its inception, but there is very little information on where these small arms were acquired and any specifics about the arms themselves are only left to speculation. In one interesting case, General Vo Nguyen Giap himself had negotiated with some French officers in 1943 for, to quote Martin Windrow, "a couple of hundred old carbines with which to fight the Japanese with". Therefore, I will start at the earliest point in which we can identify the arms involved. Although it might seem ironic in hindsight, it was the United States that first armed the Viet Minh. In August 1945, the Office of Strategic Services (OSS) sent in the Deer mission, a team of OSS personnel who was responsible for training and preparing the Viet Minh to fight the Japanese. While the Viet Minh never got the chance to do so under OSS instructions, they were supplied with a limited amount of small arms together with other vital supplies. It was still not enough to supply an entire army. More weapons were acquired when the Japanese surrendered and an additional unknown amount of arms were acquired through Viet Minh purchases of arms from China.

The Viet Minh also set up their own weapon's factories during this time but were unsuccessful in manufacturing bolt-action rifles. Copies of the British Sten submachine gun began to be manufactured in late 1946 and by 1948, the factories were beginning to manufacture bazookas and mortars. In general, the Viet Minh remained underequipped as the French Indochina War began in 1946 and as the Viet Minh was pushed out of the cities and into the countryside, their lack of weapons made them an easy target in the open. With the exception of captured weapons from French casualties, this would remain to be situation up until the great turning point of the French Indochina War: Chinese support for the Viet Minh.

1950 - 1954

With the creation of the People's Republic of China in 1949, the fruitful friendship and support that Ho Chi Minh had acquired in China throughout the years paid off as the decisions was made for the nascent republic to support Viet Minh's war against the French. Between April and September 1950, the Chinese provided the Viet Minh with over 14,000 rifles, 1,700 machine guns and mortars and anti-tank weapons numbering in the hundreds. This would only increase over the years leading up 1954 by which time the Viet Minh was fully equipped as a conventional army which included artillery and anti-aircraft guns. The arms from the Chinese were supplemented with large amount of French weapons that were captured during the spectacular Border campaign in late 1950.

But what sort of weapons were these? The captured French weapons consisted of the standard French rifle at the time, the MAS36 as well the MAT-49 submachine gun and the FM 24/29 light machine gun. There were also small quantites of the Browning Automatic Rifle (BAR) and the British Bren, all commonly captured from the Vietnamese National Army (VNA), the forerunner to the ARVN. From the Chinese, they received large quantities of Chinese and Czech Mauser bolt-action rifles as well as the Chinese copy of the Soviet PPSh-41, the Type 50. The Czech Zb26 and Zb30 was also provided to the Viet Minh by the Chinese. Smaller quantities of German weapons of Nazi origin was also captured, which had been used by the French who very much like the Viet Min had been desperate for weapons until 1950 when the US stepped in to support them.

1955 - 1975

After the French Indochina War and the creation of the Democratic Republic of Vietnam (North Vietnam), there was a drive to modernize what had once been the Viet Minh. The People's Army of the Republic of Vietnam which, would one day break down the gates at the presidential palace in Saigon, was quickly modernized and equipped with modern weapons. An unique addition to the PAVN armory was the locally made conversion of the Chinese Type 50, the K-50M. The Chinese continued to be the primary supplier of small-arms to North Vietnam throughout the Vietnam War. The Chinese Type 56 (as well as the Soviet SKS) became the standarized small arm of the PAVN until the AK-47 (some being Soviet made but most being the Chinese Type 56) was available in large numbers by the mid-1960s. Other small arms like the Soviet Mosin-Nagant and RPD light machine gun as well as weapons sold in smaller quantities from international arm sales meant that the PAVN had access to a wide array of weapons of which to use, to give to local militia or to equip the VC with. Captured US weapons were also used, but not relied on as much as captured weapons had been during the French Indochina War.

In terms of heavier equipment, the PAVN was equipped with both Chinese and Soviet produced anti-aircraft guns as well as the ever so famous SAM sites which were together with Soviet advisors. The Vietnam People's Air Force, which had existed since 1945 but which had only become an actual air force in the late 1950s, used the Soviet MiG-17 and MiG-21 (amongst others). When it came to tanks and armored vehicles, the Chinese and the Soviets supplied the PAVN with the PT-76 which was used in perhaps the only tank battle between Vietnamese forces and American forces in a confrontation that took place at the Ben Het Special Forces camp in 1969. The PAVN was also equipped with the T-34 tank as well as the T-54/55 which was first used in the Easter offensive 1972.

It is here that I would like to bring up the first use of former lend lease vehicles. As the PAVN travelled to China and the Soviet Union for tank training during the latter half of the 1950s, they returned with ex-lend lease M8 Greyhound Light Armored Cars and M24 Chaffee light tanks. While these were never actually used against US forces, it is the only solid example that I know of ex-lend lease equipment in North Vietnamese hands.

Sources:

The Last Valley: Dien Bien Phu and the French Defeat in Vietnam by Martin Windrow (Orion, 2011)

Embers of War: The Fall of an Empire and the Making of America's Vietnam by Fredrik Logevall (Random House, 2012)

China and the First Indo-China War, 1950-54 by Chen Jian in The China Quarterly, No. 133 (Mar., 1993), 85-110.

Inside the VC and the NVA by Michael Lee Lanning & Dan Cragg (2008, Texas A&M University Press)

Soviet Submachine Guns of World War II: PPD-40, PPSh-41 and PPS by Chris McNab (Osprey Publishing, 2014)

MP 38 and MP 40 Submachine Guns by Alejandro de Quesada (Osprey Publishing, 2014)