Were Similar Weapons Used In Vietnam And Iraq?

Yes and no.

in vietnam, the ARVN (south vietnamese) were armed with american cast-off weapons, of which the most popular was probably the m1a carbine. It fires a .30 caliber (.3 inch) bullet from a straight wall case, and the magazines typically held 20 or 30 rounds.  Also prominent were m-14 battle rifles which were (and still are) very popular- they fire the same diameter bullet (.308 inches) but in a much longer case, meaning it goes much faster, has a longer range, and does more damage- and is more accurate, besides.  Also, making debut appearances, were the ar-15 and m-16 family of weapons, with prototypes of what would eventually become the m-4 carbine, the m-203 grenade launcher, etc.  The stoner series of machine guns and rifles were also present, and popular, but were ultimately not adopted by the military.  These guns all fired the 5.56 ammunition, and there are many stories floating around about how bad the m-16's were because of this- this isn't the time or place for it, but the short story is that, in the prototypes, the ar-15's, one type of gunpowder was used and the rifle was designed around that: Then, when the m-16 was adopted, the gas system (which is self regulating) was advertised as self-cleaning, and no cleaning kits were included, and- at the same time, the type of powder was changed to a type that burned much dirtier and left a lot of residue. This meant that the weapon would frequently jam and malfunction.  Add to this the odd assortment of old japanese stock (7mm arisaka), the odd .50 caliber rifle (12.6x108, I believe, somebody correct me if I'm wrong?) and the standard handgun calibers- 9x19mm, .38 super, .357 magnum, and .45 caliber- and this is a pretty good picture of what was on-hand for any american or ARVN military base.

the north veitnamese, however, had a lot of russian and chinese surplus stocks.  Rifles such as the SKS and AK series, especially the AKM (distinguished from the standard AK by having a milled reciever- which means it was cut from a solid block of steel rather than made from a bent sheet of steel), and also the improvised construction performed in the tunnel systems that spanned the length of vietnam.  Both of these rifles fire the 7.62x39 russian standard round. It's about .311 caliber, if you want to compare it that way.  Other weapons include mosin nagant bolt action rifles, firing the rimmed 7.62x54 russian battle rifle cartridge, early SVD rifles probably made some appearance although I've never seen a direct reference to them.  The RPD weapon, a light belt-fed machine gun, firing the same round as the AK, was used.

the north vietnamese also extensively modified surplus russian submachine guns, such as the PPSH (from world war 2) to be a mall light carbine: Adding pistol grips and collapsing stocks, shortening the barrel, making it easy to take into cramped spaces, etc.  The PPSH fires the tokarever 7.62x25 round, which has a larger range than pretty much any submachine gun of that time period, although it was from the open bolt, and therefore less accurate because the mass of the bolt sliding forward when the trigger was pulled *but before the round was fired* affected aim.

fast forward 40 years.

NATO now uses the 5.56 round from the m-16 as it's standard round, used on such guns as the m16 A2 through A4 (simply minor variations of the same gun, starting with a heavy barrel and adding features from there, such as optic mounts and collapsing stocks), the L85 british assault rifle (you'll hear lots of complaints about this if you look for them. Apparently it falls apart when shot, although I've never shot one and can't testify to this one way or the other), the g-36 german standard rifle, the FAMAS french rifle (although they don't call it 5.56, it's essentially the same thing- just 5.56 with a bigger primer), and numerous other guns use this-- although the .308 round from the m-14 is still acceptable and is used in guns such as the g-3, FAL, Cetme, and several other guns.  


the iraq side is armed with a somewhat strange mixture. There are many soviet surplus weapons, such as ak-47's, druganov SVD rifles, Romak (cheap 'sniper' rifle) rifles, RPD and PPK machine guns, and then such things as 9x19 (nato standard) pistols and submachine guns- the browning hi-power was Saddam Hussein's favorite pistol, and is widely copied in small workshops in iraq- it's a belgian gun.  However, the weapon that stands out the most as the single most combat effective weapon is the RPG7, or rocket-propelled grenade, model 7. This is the rocket launcher that you see in all the footage that has what looks like a large metal football on the end of a tube with a scope (normally) and a trigger.  The grenades aren't always shaped like that, in fact that particular design is meant to attack armored vehicles such as tanks, but it is widely used to, eg, blow holes in walls and destroy cover. It's not particularly deadly if it doesn't directly hit somebody or a piece of metal/stone in front of them (the way it works is by pushing what it hits through the things behind it), but it does blind and deafen people it detonates next to for a short time, which usually means people fire blindly, in panic, hitting civilians and friends just as often as hitting enemies, creating a propoganda victory for the person who missed with the RPG.