Question: The M1947 Johnson auto carbine was intended as a replacement for a .30 caliber semi-automatic rifle that was standard US service rifle during World War II, the Korean War, and a limited amount when?  
Context: The M1941 Johnson Light Machine Gun, also known as the "Johnson" and the "Johnny gun", was an American recoil-operated light machine gun designed in the late 1930s by Melvin Johnson.  It shared the same operating principle and many parts with the M1941 Johnson rifle and the M1947 Johnson auto carbine. The M1917 bayonet was designed to be used with the US M1917 Enfield .30 caliber rifle, as well as with the seven different U.S. trench shotguns.  The blade was 16 inches (40.6 cm) long.  It will not fit the M1903 .30 caliber (Springfield) or the M1 .30 caliber (Garand) US service rifles as they have different bayonet ring (barrel) and attachment stud dimensions. The Karabiner 98 kurz (] ; "carbine 98 short", often abbreviated Kar98k or K98k) is a bolt-action rifle chambered for the 7.92×57mm Mauser cartridge that was adopted on 21 June 1935 as the standard service rifle by the German "Wehrmacht".  It was one of the final developments in the long line of Mauser military rifles.  Although supplemented by semi- and fully automatic rifles during World War II, it remained the primary German service rifle until the end of the war in 1945.  Millions were captured by the Soviets at the conclusion of World War II and were widely distributed as military aid.  The Karabiner 98k therefore continues to appear in conflicts across the world as they are taken out of storage during times of strife. The SVT-40 (Samozaryadnaya Vintovka Tokareva, Obrazets 1940 goda, "Tokarev self-loading rifle, model of 1940", Russian: Самозарядная винтовка Токарева, образец 1940 года) is a Soviet semi-automatic battle rifle.  The SVT-40 saw widespread service during and after World War II.  Intended to be the new service rifle of the Soviet Red Army, production was disrupted by the German invasion in 1941 resulting in a change back to the older Mosin–Nagant bolt-action rifle for the duration of World War II.  After the war new rifles were adopted by the Soviet Union, such as the SKS and the AK-47. The M1 carbine (formally the United States Carbine, Caliber .30, M1) is a lightweight, easy to use, .30 caliber (7.62 mm) semi-automatic carbine that was a standard firearm for the U.S. military during World War II, the Korean War and well into the Vietnam War.  The M1 carbine was produced in several variants and was widely used by not only the U.S. military, but by military, paramilitary and police forces around the world.  It has also been a popular civilian firearm. The M20 recoilless rifle was a U.S. 75 mm caliber recoilless rifle used during the last months of the Second World War and extensively during the Korean War.  It could be fired from an M1917A1 .30 caliber machine gun tripod, or from a vehicle mount, typically a Jeep.  Its shaped charge warhead, also known as HEAT, was capable of penetrating 100 mm of armor.  Although the weapon proved ineffective against the T-34 tank during the Korean War, it was used primarily as a close infantry support weapon to engage all types of targets including infantry and lightly armored vehicles.  The M20 proved useful against pillboxes and other types of field fortifications. An AK-22 "Trainer" is a semi-automatic rifle loosely based upon the AK-47 in its design, and chambered in .22 long rifle calibre.  The firearm currently sold on the civilian market in the United States of America dubbed as the AK-22 "Trainer" is manufactured in Romania by "S.C. Uzinele Mecanice Cugir S.A".  Despite the common belief, the AK-22 is not normally used to train regular troops either in Romania or in other countries.  While until recently the use of rimfire rifles replicating the standard service rifles in its dimensions and features had been common in several countries for training soldiers in basic firearms handling and marksmanship, at present this use has been abandoned due to the enormous availability of service weapons and ammunition already in stock, and the fact that a rimfire rifle, with its low recoil, doesn't help accustom a recruit to the recoil of the regulation rifle they will use in their normal service life; rimfire rifles are however used in many countries for basic firearms handling and standard marksmanship training within Armed Forces' "Youth Corps" (Cadets).  The AK-22 is thus intended merely as a civilian sporter rifle.  Its average price ranges within 200 and 500 US$. The M1 Garand is a .30 caliber semi-automatic rifle that was the standard U.S. service rifle during World War II and the Korean War and also saw limited service during the Vietnam War.  Most M1 rifles were issued to U.S. forces, though many hundreds of thousands were also provided as foreign aid to American allies.  The Garand is still used by drill teams and military honor guards.  It is also widely used by civilians for hunting, target shooting, and as a military collectible. The M1947 Johnson auto carbine is a semi-automatic derivative of the M1941 Johnson machine gun.  It was intended as a replacement of the M1 rifle but not accepted.  The auto carbine never got past the prototype stage, only five of them ever being made. The Gewehr 43 or Karabiner 43 (abbreviated G43, K43, Gew 43, Kar 43) is a 7.92×57mm Mauser caliber semi-automatic rifle developed by Germany during World War II.  The design was based on that of the earlier G41(W), but incorporating an improved short-stroke piston gas system similar to that of the Soviet Tokarev SVT-40, and it incorporated innovative mass-production techniques.
Answer: Vietnam War