One of the first guns seen in the film is the M1 Garand, seen carried by National Guard soldiers protecting black students during the integration of the University of Alabama. National Guardsmen are also seen with M1s slung when guarding the rioters protesting the war in Vietnam.
M14
During the scenes when Forrest Gump (Tom Hanks) is training at Boot Camp, he and the other recruits are seen assembling and disassembling M14 rifles, Forrest finishing his in record time.
M16/XM16E1
U.S. Soldiers, including Forrest Gump (Tom Hanks) in Vietnam are seen armed with M16 rifles, which due to continuity error change from slab-side M16s to XM16E1 rifles, which feature forward assists. Both rifles feature three-prong flash-hiders, so it is difficult to tell them apart from the left side of the rifle.
M1911A1
While in Vietnam, Forrest Gump (Tom Hanks) is handed an M1911A1 for "Tunnel Rat" duty, and later his commanding officer, Lt. Dan Taylor (Gary Sinise) is seen using one after he is wounded during the battle.
M60 Machine Gun
M60 machine guns are seen mounted on UH-1 Huey helicopters in Vietnam and carried by some of the U.S. soldiers.
M72 LAW
M72 LAW rocket launchers are seen on several soldiers rucksacks, including Forrest Gump's (Tom Hanks), though none of them are ever used.
During the flashbacks of Lt. Dan's (Gary Sinise) ancestors who died in battle, one who died during the American Revolution is seen armed with a Flintlock Rifle.
Colt 1860 Army
During the flashbacks of Lt. Dan's (Gary Sinise) ancestors who died in battle, one who died during the Civil War has a Colt 1860 Army in his hip holster.
M1903 Springfield
During the flashbacks of Lt. Dan's (Gary Sinise) ancestors who died in battle, one who died during World War I is seen using an M1903 Springfield.
M1928A1 Thompson
Another one of Lt. Dan's ancestors, who died during World War II, is seen holding an M1928A1 Thompson submachine gun.
Remington 870
A "Black Panther" is seen holding a Remington 870 in a photograph pinned to the wall during the "Black Panther Party".
Colt Official Police
A nickel plated Colt Official Police is seen wielded by a "Black Panther" during the "Black Panther Party".
One of the "Black Panthers" is seen armed with an Ithaca 37 shotgun.
Sharps Rifle
When Forrest Gump (Tom Hanks) is asked to join the U.S. Army, a statue behind him is of a Civil War soldier armed with a Sharps Rifle of unknown year.
Rohm RG-14
The archive footage of the Assassination Attempt on Ronald Reagan shows John Hinckley Jr. firing a Rohm RG-14 .22 caliber blue-steel revolver.
Colt Detective Special/Smith & Wesson Model 36
Arther Bremer used either a Colt Detective Special or a Smith & Wesson Model 36 to shoot and wound Alabama Gov. George Wallace during his Presidential Campaign. Archival footage is shown but it is hard to make out which gun it is because you only see it for a brief second and the footage is from 1972.