M*A*S*H (or simply spelled as MASH) was the television adaptation of the 1970 film of the same name. As in the film, the series followed the antics of the medical personnel assigned to the 4077th Mobile Army Surgical Hospital. Though set in the Korean War, the series was meant as an allegory to the then ongoing war in Vietnam. The series aired on CBS for 11 seasons from 1972-1983 and its finale was one of the most viewed television programs in history.
The following weapons were used in the series M*A*S*H:
LTG "Iron Guts" Kelly (James Gregory) carries two nickel plated M1911 with pearl grips as his sidearms in Ep. 3.04 "Iron Guts Kelly".
Star Model B
For the majority of the series, the Star Model B was used as a substitute for the M1911A1 that would be standard issue, since blank .45 ammo was more rare than 9mm at the time. It is used by many characters throughout the series, notably MAJ Frank Burns (Larry Linville) and (Harry Morgan) as both MG Bartford Hamilton Steele and as COL Sherman Potter. CPT Benjamin Franklin "Hawkeye" Pierce (Alan Alda) disdains guns, though he uses one in Episode 5.10 "Hawkeye, Get Your Gun" to scare Chinese forces.
Burns has a Star Model B with pearl handles. As the comic foil, he frequently breaks every rule of gun safety in spades, despite being "regular Army."
Colt Commander
The Colt Commander is seen used by characters throughout the series, probably as a substitute for the regular Colt M1911 as the Colt Commander was not a common pistol seen during the Korean War.
In the Episode 1.16 "The Ringbanger" Henry uses his service pistol. In the Episode 2.13 "Deal Me Out" Captain Halloran (Edward Winter) draws his service pistol because of gunfire in the camp (Winter would later become better known in the series as COL Flagg). In the same episode, PVT Carter (John Ritter) threatens Frank in the shower.
Colt Model 1908 Vest Pocket
In Episode 3.2 "Rainbow Bridge" Houlihan gives Burns a Colt Model 1908 Vest Pocket with pearl grips for a concealed weapon before going to a wounded pickup in Chinese territory, in spite of the Chinese saying they were not even to have sidearms. Fortunately the Chinese are so amused by the diminutive size they laugh it off.
Colt Single Action Army
In Episode 1.08 "Cowboy," a chopper pilot has two Colt Single Action Army revolvers with pearl grips as his sidearms.
Colt New Service
In Episode 4.13 "The Gun," a wounded Colonel arrives at the 4077th with a revolver described as a chromed Colt .45, shiny barrel with bone grips, made in 1884. The year suggests that pistol is supposed to be a Colt Single Action Army, though the actual revolver is an anachronistic Colt New Service model, which wasn't introduced until 1898, 14 years later.
Smith & Wesson Model 19/66
COL Potter uses a Smith & Wesson snubnose as a starter revolver in Episode 6.10 "The M.A.S.H. Olympics." They alternate between the blued Model 19 and the stainless Model 66.
The M1928 Thompson is occasionally carried by some soldiers, as a stand-in for the M1.
PPSh-41
Chinese soldiers in Episode 3.2 "Rainbow Bridge" are armed with Soviet PPSh-41 SMGs during the wounded pickup. If they were Chinese-made Type 50s, they would use stick magazines instead of drums, though North Korea did make licensed PPSh copies as Type 49s.
MP40
A Korean soldier (Soon-Tek Oh) surrenders in Episode 4.06 "The Bus" with an MP40, which MAJ Burns uses while guarding him.
Rifles
M1 Carbine
Several US Army and UN soldiers are seen with M1 Carbines. CPL Maxwell Klinger (Jamie Farr) is seen with one during patrol in a couple instances. 1LT Smith (William Watson) uses one to demand treatment for his Sergeant in 3.12 "A Full Rich Day."
M1 Garand
The M1 Garand also appears as a regular service rifle, used by the Camp's enlisted men on guard duty (notably CPL Maxwell Klinger (Jamie Farr) before he becomes the company clerk), US soldiers and other UN allies.
Valmet M71
In Episodes 6.12-13 "Comrades in Arms," Korean patrols appear to be carrying Valmet M71 Sporter riles with synthetic furniture and the muzzle brake removed, to represent AK-47s. While this is a reference to the Vietnam War, any AK-47 variant used in the Korean War is likely an anachronism, since even the Soviet Union and China did not issue AK-type rifles until years after the Armistice was signed in 1953.
Mosin Nagant M91/30
Radar tells his Mum that an North Korean soldier was steeling food in the mess tent in Ep. 4.16 "Dear Ma". A surrendering North Korean soldier (Soon-Tek Oh), who is nicknamed "Ralph" by Hawkeye, as well as a North Korean patrol they encounter appear to be using Mosin Nagant M91 rifles in Episode 8.10 "The Yalu Brick Road."
Chinese SKS Type 56
On his way to R&R, Hawkeye is shot at by a North Korean soldier (Mako) who holds him at gunpoint with his Chinese SKS Type 56 rifle, forcing him to treat his wounded comrade S09E01 "The Best of Enemies"
Machine Guns
Browning M1919A4
A Browning M1919A4 is mounted on a US Army jeep during the retreat in Episode 5.01, "Bug Out".
Shotguns
Double-Barreled Shotgun
MAJ Charles Emerson Winchester III (David Ogden Stiers) managed to get his shotgun sent from home for fowl hunting in Episode 8.12 "Dear Uncle Abdul." It's a hammerless break action side-by-side shotgun. As a nod to his character namesake (and affluence), it is possibly a Winchester Model 21 or 24 though the receiver is never clearly seen. MAJ Margaret Houlihan (Loretta Swit) borrows it during the episode.
Other
Mk 2 hand grenade
Mk 2 pineapple grenades are occasionally seen on passing GIs. Klinger threatens Father Mulcahy after an disput with Frank Burns in Ep. 1.12 "Dear Dad". SSG Rizzo (G.W. Bailey) borrows a dummy grenade from PVT Igor to play pranks in Episode 11.15 "As Time Goes By." As another nod to the Vietnam War, these grenades are painted black. Mk II grenades during the actual Korean War would be olive drab in color.
3"/23 caliber gun
The 4077th is supplied with a "40mm gun" in Episode 2.2 "5 O'Clock Charlie" when he starts trying to bomb an ammo dump near the hospital. This is actually a Navy 3"/23 caliber gun, similar to the one used in The Sand Pebbles.
M116 Pack Howitzer
In a poker wager, Hawkeye was the winner of an army jeep from a supply sergeant in Episode 7.11 "Dear Comrade." However, he is delivered what appears to be an M116 pack howitzer.