Improperly Placed Firearms

The practice of giving inappropriate firearms to characters or factions in a TV show or movie. They're generally inappropriate because they are either outdated, too modern for the setting, or because the group in question wouldn't have access to them (like Soviet soldiers wielding Uzis)

Needless to say, it isn't restricted to guns, but they are always the first and most notable victim. Which is strange, as it's generally a lot easier to get a few MP-40's than to arrange for a Tiger tank to show up in your production.

One reason this can happen (especially for things more expensive than guns) is that the "right" weapon may not be available, and an incorrect version easier to come by than it would be to make a replica. For example, Chinese AK clones commonly stand in for the real thing in American movies made during the Cold War. An extreme case would be armoured vehicles; there is only one WW 2-vintage Tiger tank that still runs in the entire world and leasing a running mock-up from a private collection would be far more expensive than simply using some other tank and hoping the audience doesn't figure it out. This goes even more for ships; before modern CGI, movies were often forced to either use contemporary warships (even with a stratospheric budget, Pearl Harbor's Japanese carrier set was built on the deck of a modern carrier, made obvious by the visible steam catapult runs) or unconvincing models.

While guns are a fairly mature technology with most new designs being more ergonomic then mechanically different, some shows will push this and it gets unrealistic when a gun is still in use in an entirely different universe, 1,000,000,000 years from now, or 100 years before it was designed.

See also AKA-47, Selective Historical Armoury, Just Plane Wrong and Artistic License Ships.


 * The king of this trope would have to be the M1911 service pistol (usually the M1911A1 variant specifically), which regularly gets star billing playing itself. In series as diverse as the Honor Harrington novels (set in the year four thousand or so) and John Barnes' Timeline Wars, protagonists have used this gun in combat situations. Nevermind that Honor's pulser can rip apart a tank, and Mark Strang's SHAKK can do so at six miles, with two thousand homing rounds it can synthesize from scrap metal.
 * To be fair, Dame Honor is in the SCA, and thus practices the use of such an antique weapon. The antiquity of the weapon is also pointed out in the text, making it more like a modern character practicing archery.
 * Honor Harrington's M1911, a replica built from the original design, was a gift. Three factors: her uncle was in the SCA so she'd learned to fire "chem burner" guns at a young age; dueling pistols on Manticore are 10mm "chem burner" automatics (because a hit from one can be survivable and the preferred dueling protocol is a single shot each), and the gift was from the Protector of Grayson (a planet whose tech base had become low enough before their alliance with Manticore they couldn't produce small enough grav-drivers to make pulser and so had to use "chem burners"). She did kill a mass murderer with her M1911 because as it uses chemical propellant it could be concealed without a scan for energy sources picking it up, but her signature weapon is probably either David Weber's latest "uber tech" for slaughtering Havenite ships or the pulser built into her artificial arm.
 * She also has a sword, and is rather skilled with it.
 * Also justified for Strang: he starts as a historian and bodyguard in our present (subjectively before being drafted by the Time Police), where he uses the M1911 because of its durability and intimidation value. And if you lose your BFG in the past, it helps to have a backup you can find bullets for.
 * Here's the IMDFB page for the M1911 series.
 * The 1911 style pistol's continuing existence is more likely than you think. As the name implies, the design is already 100 years old and it is STILL one of, if not THE, most popular pistols in the world. Aside from being the basis for almost every automatic handgun on the market today, everyone and their mother makes a copy of it and it's probably second only to the AK-47 and variants in terms of number built. Also, let's not forget that there are still black powder shooters who own and shoot cap & ball revolvers, the designs of which are over 150 years old. It's not two thousand years, but it's a start.
 * A very common one is use of the wrong AK variant. Sometimes you see Soviet/ex-Soviet soldiers in a reasonably modern setting wielding AK-47s. In reality, they'd been mostly replaced in Soviet service by the AK-74 (which can be identified by a smaller, less-curved, orange-coloured magazine, as well as a large muzzle brake on the end of the barrel). Lord of War is an example. Recently, however, 7.62-mm AKs, either former mainstays of the AKM line, or more modern AK-10x series, made a resurgence, after combat experience in Afghanistan and Chechnya demonstrated that the lighter bullet of the AK-74 tends to ricochet at the slightest prodding, and is thus unsuitable in forested areas. Thus there can be some unexpected aversion, when a bumbling producer who just doesn't care accidentally gets things straight.
 * In reality, the AK-74 was just starting to make its way to the export market before The Great Politics Mess-Up. The vast majority of AK variants in the world are of the AKM variety or the Chinese Type 56 clone, both firing the original 7.62x39mm cartridge.
 * Misidentification of pistol caliber in live action TV/movies. Hollywood pretty much standardizes around the 9mm blank, so many firearms identified as .40S&W or .45ACP will often have a 9mm "stand in." With something like a Glock, which comes in several different calibres and variants, it's barely even noticeable. With the M1911, a common stand-in has been the Spanish Star Model B, a visually similar 9mm pistol, especially in older movies made before 9mm chambered 1911s existed. Still, visually telling the difference between a 9mm and .45 barrel is very very tough, and made even more because we never look straight down them.
 * Substitution of a common firearm variant for a rare one. Machine pistols such as the Beretta 93R or the Glock 18 generally aren't sold outside of government agencies even if the armsmaster has a Class III permit; the usual solution is to drop a full-auto sear into the semiauto variant. In fairness it's not particularly hard to dress a Beretta up as a 93R, and the only obvious difference between semi and full auto Glocks is the ported barrel which you can only see from above, so most people aren't going to lose much sleep over doing this.(The Joker's Glock in The Dark Knight is one notable example).

Anime and Manga

 * Played straight and subverted in Angel Beats!. The characters use realistic guns, which operate as one would expect guns to, but they're supposed to be in high school. However, it turns out they're actually in a sort of Purgatory, and said weapons can be created and used, so long as the engineers who created them also knew how the thing worked. Which is hilariously subverted in episode 2 when they pull out a gigantic cannon to use against Angel, and the entire thing blows up in their face since none of them knew the mechanics of an artillery gun.
 * Cowboy Bebop is set in a future with space gates, large spaceships and advanced almost-sentient computers, yet every personal weapon seen is either very similar or exactly identical to present-day ones. Spike himself uses a Jericho 941. The anime tries to convey the idea that it's set in a somewhat realistic and retro future, so it makes sense that there are no blasters and that energy weapons are few and far between (though it's never explained how Spike got a plasma cannon on his Swordfish when even police fighters are restricted to machine guns). You'd think personal firearms would have evolved at least a little. Plenty of the main cast's weapons are out of date now, but then everything in Cowboy Bebop is retro!
 * It's worth noting that Spike's dated Jericho can fire in the vacuum of space. The pistol might be mundane, but the bullets are better than what you can buy today.
 * This troper just assumes that these are modern, up-to-date weapons built in the image of classic firearms, but using updated technologies to make them perform better and longer. Like be able to shoot in space without breaking down after a few shots.
 * In Gankutsuou, which takes place in the 50th century, Danglars uses a gold-plated PPK/S, and Morcerf a gold-plated P08.
 * Code Geass is rather strange in this regard. Taking place in an alternate timeline, most of the firearms seen are fictional, but the few identifiable ones seem like very odd choices in the context of the series. The standard Britannian pistol appears to be a slightly modified Heckler & Koch USP .45 or Mark 23 pistol, while the service rifle looks like some kind of cross between a FAMAS and an FN P90. Considering that, in-universe, the EU and Britannia are mortal enemies, it makes very little sense for Britannian troops to be using German, French, and Belgian arms.
 * The ECOAS spec ops troops in Mobile Suit Gundam Unicorn use FN P90s, despite the series taking place at least a century or two into the future.
 * Most of the guns in the Ghost in the Shell franchise are based on real-world weapons, some of which are outdated today (even though the series takes place circa 2030 A.D.) and are frequently Rare Guns as well. The FN-P90 seems to be particularly popular with the creators.
 * Noir both subverts this and plays it straight. Of the main characters, Mirielle uses a modern Walther P99, which subverts this. This trope is played straight with Kirika's Beretta Md. 1934. Instead of giving her the more widely available Walther PPK (which uses the same cartridge and is almost exactly the same size), the production staff deliberately gave her an out-of-production World War 2 vintage pistol because they didn't want to give her "the James Bond gun".

Film

 * In the film Aliens:
 * Hicks carries as a backup an Ithaca 'Stakeout' shotgun, and the Marines' sidearm, called the VP 70, is a real, unaltered weapon. The Sulaco's weapon racks are also filled with unaltered modern weapons; M16s, Colt Commando rifles, and Enfield L85s. Vasquez also uses a Smith & Wesson Model 39 pistol at one point.
 * Alan Dean Foster hangs a Lampshade on the first of these in his novelization of Aliens, when one of the Marines asks Hicks if he got his pump-action shotgun from a museum.
 * Bear in mind that the gun props in Aliens look suitably futuristic enough that they actually avert this trope for anyone who's not a firearms expert. The M41A has become iconic in its own right.
 * The movie Pitch Black featured a shortened SPAS-12. It either shot slugs or was an energy weapon in the movie.
 * In Escape from New York the United States Police are armed with M16s with the handguards removed (which would burn the hands of the people using them).
 * In Rambo movies, you will notice many. Since part of Rambo 3 was filmed in Israel, the production had access to genuine Soviet hardware captured during the wars with the Soviet-backed neighbours while it was there.
 * Russian helicopters fitted with western weapons (such as the FN MAG machine guns) and even western helicopters with attachments to make them look like Russian choppers (and made them extremely difficult to fly).
 * ZSU-23 Shilka replica made using M113 chassis in Rambo 3.
 * AKMs, AKMSUs, or Chinese AK replica modified (such as adding the muzzle brake) to look like AK-74 and AKS-74s since Hollywood did not have access to those weapons at those times.
 * A fake SVD made from a Valmet with an SVD-style stock in the second movie.
 * M2 Browning heavy machine guns dressed up to look like Soviet heavy machine guns.
 * In the sci-fi movie Enemy Mine the human pilot is armed with a stainless steel Walther PPK.
 * In Raiders of the Lost Ark the main weapon of the Nazi soldiers is the MP-40, despite the movie taking place in 1936. More jarring is the fact that at the end of the movie, Indiana Jones threatens the bad guys with an RPG-2, a Soviet rocket launcher that wasn't even designed until a few years after World War II.
 * The MP-40 was the MP-38 slightly redesigned to be cheaper to manufacture, and the two are visually nearly identical, but still falls 2 years too short. This does however explain the MP40 appearing in the sequel Indiana Jones and the Last Crusade which is set in 1938.
 * Justified in Lifepod (the sci-fi remake of Alfred Hitchcock's Lifeboat) where one character is carrying a 20th century revolver because it will get through spaceport detectors that will pick up contemporary energy weapons.
 * A case of being a bit too accurate is in the movie adaptation of The Fourth Protocol, where the KGB agent played by Pierce Brosnan uses a Soviet Makarov pistol—as an 'illegal' carrying out an operation that must not be linked to his own country it's the last weapon he'd use.
 * Remo Williams had the hero being tracked as he ran through the woods by what was actually the High Power Illuminator Radar. It is the distinctive 'Mickey Mouse ears' system. This is a radar meant to 'spotlight' a target for the MIM-23 Hawk surface-to-air missile.
 * The film Zulu had a few examples:
 * While the production crew acquired plenty of period accurate Martini-Henry rifles, the production used up all of the available blank cartridges for its obsolete caliber. Thus, some extras wound up with anachronistic Lee-Enfield No. 4 Mk I bolt-action rifles instead.
 * Also, officers used Webley Mk VI revolvers in lieu of period-accurate (but difficult to procure) Beaumont-Adams revolvers.
 * The movie version of The League of Extraordinary Gentlemen used several anachronistic guns with cosmetic changes. Dorian Gray used a gilded Luger P08, Captain Nemo used a Tokarev TT-33 pistol with ornate external decorations, his men have equally ornately-decorated Sten Mk II submachine guns, and the antagonist's mooks used Uzis, Thompsons, and AK-47s essentially encased in rectangular metal boxes.
 * They also used Mark V Tanks which was developed at the very end of WW 1- in 1899!
 * In the film A Bridge Too Far, most of the American paratroopers (including their Colonel, played by Elliot Gould) are seen carrying the M1 carbine, rather than the modified M1A1 carbine (a smaller, easier to carry weapon with a folding wire-stock) that was specifically designed for and issued to American paratroopers.
 * Hilariously in the film version of Bulletproof Monk, the Nazi villain's Mooks use Uzis.
 * The James Bond movie Octopussy had a scene with Soviet border guards armed with Steyr AUGs.
 * In A Few Good Men, Kaffee notes that Lt. Colonel Markinson committed suicide with a .45, yet the scene depicting his death clearly shows him shooting himself with a Beretta.
 * Averted in Buffalo Soldiers in a nicely self-referential way. The plot revolves around how relatively easy it was to sell off large amounts of weapons stolen from US army bases in Germany. After the Cold War ended and US troops returned home, vast amounts of materiel were left behind. One member of the film crew owned 100 of the appropriate guns to lend the production. Where one character is given a particularly heavy gun to carry on exercises as a punishment, there was some difficulty in sourcing this gun.
 * Captain America the First Avenger has the British agent Peggy Carter, whose weapon is a Walther PP handgun. The movie occurs during World War II, when the most famous users of this gun were the German police and the Nazi Party officials. It is maybe a volontary anachronism, this gun is today mostly known as the signature weapon of James Bond.

Literature

 * A rare literary example can be found in Brian Daley's Hobart Floyt/Alarcrity Fitzhugh adventures: Despite the far-far future setting, Hobart's personal weapon is a Webley Mark IV revolver. It's specifically stated to be a modern reproduction from a frontier planet which needed a sturdy and reliable last-ditch survival weapon.
 * On the cover of Paratime by H. Beam Piper, the main character is shown holding a Steyr AUG assault rifle. This was the artist's error; what the character actually had in the story depicted was a bolt-action hunting rifle from an alternate timeline. U.S. law-enforcement types in our timeline's 1948 thought it looked unusual and advanced ... but not extraordinary or science-fictional. Ironically, the artist was spot-on with his depiction of the monster attacking the hero.

Live Action TV

 * Star Trek: Voyager once featured the smallest of the Calico SMG variants as pistols (guess the 50-round magazine was just convenient).
 * There is a pistol version of the Calico actually: the 9mm M950 which can take a 50 or a 100 magazine. Due to their unique appearance Calico firearms have appeared in several sci-fi movies, including "I Come In Peace" (aka Dark Angel) and the parody Spaceballs.
 * The terrorists in that particular Voyager episode ("Time and Again") also used the Detonics Pocket 9. At least the producers went to the trouble of selecting weapons that looked different from regular firearms.
 * The Doctor Who story The Impossible Planet features the people on the base wielding P90s, a gun which would be several thousand years old at that point.
 * Utopia then takes it to a completely ridiculous extent. Guards are shown using Dragunov sniper rifles (a gun designed in the late '50s) in the year 100 trillion. For reference, the universe right now (in the real world) is allegedly 13.7 billion years old. This episode takes place over seven thousand times the age of the universe into the future (95.9 trillion), and they're still using a gun that is almost obsolete now!
 * On the other hand, Utopia does have a Just Before the End setting where it's implied that there's no longer the resources or population to keep high technology working.
 * The Doctor's Daughter features a Webley revolver in a futuristic clone-war. Yes, the favoured weapon of the original Brigadier. It also featured P90 gas-jet mock-ups, oddly enough. Couldn't they have just reused the G36s they had on hand?
 * The soldiers in The Time of Angels/Flesh and Stone also use P90s, although these have phony suppressors dummied on to increase their length. Interestingly, the suppressors resemble Dalek extermination beam projectors.
 * River Song has used the futuristic-looking COP derringer also seen in Battlestar Galactica Reimagined - although River's has an integral blowtorch.
 * A well-known old school example is the prominent use of MAC-10s by future (or alien, it isn't clear) Private Military Contractors in "The Caves of Androzani".
 * The 1960s-era series Combat! (set in World War II) sometimes used what appeared to be M3 submachine guns (which were actually issued to US troops at the time) with some modifications in external appearance in place of Nazi MP-38s or MP-40s.
 * Similarly disguised Reising submachine guns were also used in some episodes. Like the M3, the Reising was also distributed to US troops in WW 2, though in more limited numbers.
 * The Airwolf episode "Mad over Miami" features a bad guy holding something he claims is a new American heat-seeking missile launcher, which he uses (unsuccessfully) on Airwolf. It's very clearly an RPG - a Soviet rocket launcher with no heat-seeking capability.
 * In the Airwolf pilot movie, a HAWK missile is seen launching, to be identified by the heroes as a 'heat seeking missile' (the HAWK is a semi-active radar guided missile).
 * In an episode of The Seventies TV series The Professionals, where the Bulgarian secret service mooks at a prisoner exchange are holding StG-44s. This weapon was used in a few Warsaw Pact countries, but only as an interim substitute for the AK 47 and they were long gone by the 1970s.
 * Stargate SG-1 both commits and averts this trope, often even in the same scene. From season 4 onwards, the team's MP5 submachine guns (which ARE issued in the U.S. military) were replaced by the Belgian FN P90 personal defense weapon. The only American users of the P90 are the Secret Service and some U.S. law enforcement agencies. However, actual U.S. military weapons also appear in the show quite often: the Beretta M9 pistol, the M4A1 carbine, the M16 assault rifle, and the M249 SAW to name a few. Another straight play of the trope occurs much later in the series: when Cameron Mitchell joins the team, the SGC starts using the H&K G36 and MP7 PDW.
 * The Word of God is the 9mm round fired by the MP5 was simply not powerful enough to reliably penetrate Jaffa armor, resulting in a lot of ammunition expended for little purpose. SGC switched to the P90, along with assault rifles, specifically because the 5.7mm round has extremely good penetration against a variety of materials (which was its design intent), making it more effective against Jaffa than the MP5.
 * SG-1 is not primarily a combat team, being diplomats and scientists. This would make a real rifle, which the combat focused SG teams do use, impractical.
 * Note that non-combat personnel who will need to defeat body armor if they ever do fight was the P90's intended niche. Firearms enthusiasts have noted the irony that the Stargate program actually found a proper place for the P90, as the intended situation no longer exists in the real world with the end of the Cold War.
 * During the opening phases of the second Gulf War, it was necessary for the Stargate production crew to cut down on their use of the P90, with it only being carried by O'Neill, whilst Carter carried the 'Carter Special'. This was due to the fact that factories that would otherwise have produced the 5.7mm blanks were busy producing live rounds.
 * This trope is played glaringly straight almost any time the SGC runs into an offworld civilization that's using firearms. There is one episode where the other civilization was clearly using M1 Garands and AKs.
 * The use of (for example) the P90 by Stargate Command has some real-world plausibility, even though it's not standard U.S. military equipment. In real life, Special Operations Command can make use of RFI (Rapid Fielding Initiative) to bypass the usual slow-moving procurement system and buy whatever they need directly. SGC would be in a somewhat analogous position to SOCOM (i.e., a relatively small but well-financed and highly important element of the military), quite possibly with even more RFI freedom.
 * There was an episode of Hogan's Heroes where an American M7 Priest (a self-propelled artillery piece from WW 2), painted grey and given iron cross decals, stood in for a German AFV. They even use the Priest's gun to set off some dynamite they've wired to a bridge at one point.
 * The Peacekeeper Pulse Rifle from the show Farscape bears a remarkable similarity to the Steyr ACR, sans magazine and wrapped in tin foil.
 * An in-universe example in an episode of Jake 2.0, where one of the clues that the guys holding him are not German Secret Service is that one of the guys has a Walther PPK. Being a Hollywood Nerd, he instantly recognizes James Bond's favorite gun. He's also an experienced NSA agent, so he knows that nobody uses these anymore. The other clues are constantly-dropped movie quotes ("Can you outsmart a bullet?") and a watch too expensive for a government agent. Turns out they were just hackers (American hackers) playing a prank on him (or rather, on the person they think is their leader).

Video Games

 * In GTA 3, FBI agents at the 5th wanted level strangely carry AK-47s, an odd weapon for American law enforcement to carry. In the other GTA 3-era games, they carry MP 5 s, a more plausible weapon and one which acts in the game as a more logical "mid-power" weapon between the Uzi carried by the level-four SWAT teams and the M16s carried by the army at six stars, while the AK is carried only by criminals after GTA 3
 * Although Serious Sam, with a 22nd century protagonist, has a fully-automatic rocket launcher (still a dream) and a laser weapon (ditto), but it also features archaic weaponry, including unlimited-reload Schofield revolvers, a manual-loading snap-open double-barreled shotgun, an unashamedly labeled Tommygun and a man-portable cannon (of the cannonball variety). All of which are hilariously out-of-place in ancient Egypt.
 * But for very good reason.
 * In Hidden & Dangerous 2 and its expansion pack you face Italian soldiers that wield German firearms and tanks. The Japanese feature about the same amount, but in their case the developers took the time to model appropriate weapons. There are also some Italian-model aircraft on the field, yet the pilots seen wear Luftwaffe uniforms.
 * The box art for Wolfenstein 3D depicts Nazis using M16s, that fire while falling through air no less.
 * The box art for its Spear of Destiny expansion features the hero smashing open the glass case of the titular spear with a Kalashnikov.
 * Return to Castle Wolfenstein has the female Nazi Elite Mooks all wielding British Sten guns. Whether this is acceptable is up for debate, since the Germans did make their own copies near the end of the war.
 * A similar example: In the demo version of Medal of Honor: Airborne Assault the player faces Italian blackshirts armed with German weapons like the Kar-98 and MP-40 in a small village in Sicily.
 * This continued in the Breakthrough expansion pack's Italian missions, in spite of the expansion adding authentic Italian weapons and NPC models for use in multiplayer.
 * During the introductory assault course in Modern Warfare 2, the range master is seen brandishing a chrome-plated Desert Eagle and gives another one to the player character. Keep in mind these are US Army Rangers in Afghanistan: Desert Eagles are definitely not standard issue, and getting caught using an unapproved firearm can land you into serious trouble. Then again, the weapon boxes he opens before you run the Pit also contain a number of weapons that aren't standard-issue, and nobody ever complains if you drop one of your starting guns for one that someone had just been trying to kill you with (hell, Soap at one point in MW2 directly asks if you "see anything you like" in the Gulag's armory), so the concept of unapproved firearms may not even exist in the game's universe.
 * What's funny to note about Modern Warfare 2 is that only 2 of the weapons the Russians use make any sense. These are the RPG-7 and the Dragunov SVD- most of the others they use aren't even Russian, for example the Israeli TAR-21, the French FAMAS, or the Austrian Steyr AUG. The other ones that ARE Russian, such as the RPD and AK-47, have been replaced for military use already.
 * Even the RPG-7 is almost obsolete now due to its inability to effectively defeat most modern tank armor.
 * "Remember, no Russian."
 * There's also the “G18,” which is a modified Glock 17 standing in for the full-auto Glock 18. As mentioned at the top of the page, this is a common occurrence in films. Presumably one of the many modified full-auto Glock 17s owned by a Hollywood gun provider was 3d-scanned or otherwise the basis for the model.
 * Taken to an extreme in Call of Duty Black Ops which features several anachronistic faults in regards to firearms shown in the game. The FN FAL in particular - commonly known as the "Right Arm of the Free World" for its use by many Western-aligned nations - is only used by Vietcong and Cubans in single player. Soviet special forces in '60s Kowloon also get the SPAS-12 shotgun – from Italy and introduced in 1982. Bizarrely, the KS-23 pump-action shotgun (which was at least Russian, although still not designed until the 1970s) makes an appearance during several other levels in Soviet hands.
 * The Russian army in Battlefield: Bad Company 2 uses two Russian assault rifles and a handgun alongside Chinese machine guns and sniper rifles and a Swedish RPG. What's even weirder is that the game features a wide assortment of much more sensible modern Russian firearms, but the majority of them are only usable in multiplayer.
 * While all the other guns in the original Unreal Tournament are futuristic enough, the game's sniper rifle is merely a long-barreled M16 with a scope attached to the carry handle. Lampshaded in the official site's timeline of the series, where the in-universe explanation for replacing it with the Lightning Gun in UT2003 was that it was "a relic of centuries past".
 * In Halo, set about five hundred or so years in the future, the UNSC apparently still uses twentieth-century South African 20mm anti-materiel rifles (albeit converted to semiautomatic fire and with the magazine in the bottom rather than the side of the rifle).
 * The Grease Gun shows up in the non-WWII game Soldier of Fortune 2, in which it serves as the main assault rifle of the... Czechoslovakian army.

Western Animation

 * Seth MacFarlane shows technically fall into this with pistols: all are drawn as the exact same model, but are identified as what the character in question would logically be using. For example, in Family Guy, all pistols appear as M1911's, but in one episode Stewie identifies one held by an Army recruiter as an M9.

Real Life

 * Andy Rooney (who was a correspondent during WWII) once told the story of a platoon of American soldiers who came across a German weapons cache. Either out of curiosity or necessity, they equipped themselves with the best guns the Third Reich had to offer. To paraphrase: "A U.S. mortar team, hearing the familiar sound of German firearms to their flank, dropped round after round on that position until the firing stopped..."
 * In Generation Kill, Captain America is chewed out by his very annoyed Sergeant for this very reason.
 * This was why the US discouraged its soldiers from taking AK-47s in Vietnam. They are the preferred weapon of the enemy, which make a distinctive sound when fired. However, at the time US riflemen were equipped with an early model of the M16 which was notorious for design faults and a tendency to jam at inappropriate moments, no matter how well looked after. The AK-47, by contrast, was and still is famed for its durability and reliability, so it boiled down to a choice between being unable to shoot anyone or being shot at by everyone.
 * The issue there was as much a combination of advertising the weapon as low maintenance, combined with a change (between prototype and production) in the propellant powder used which made it anything but. There is also the issue with the rifle's direct impingement operation that tends to foul up the innards really quickly.
 * For the same distinctive sound, Special Forces teams used them instead of the M16. Any enemy hearing a shot simply heard a fellow soldier shooting enemies.
 * Similarly, there was at least one American unit in World War 2 that got itself trapped behind German lines and ran low on supplies. They ended up having to hunt venison using captured German rifles to avoid alerting enemies to their presence. On the other side, German riflemen issued with the Gewehr 43 apparently hated the gun and, if they had the option, would use captured American semi-auto rifles instead.
 * The Germans also had a love for the PPSh-41, and whenever they could picked them up. It got to the point that it even received a German model number, as the MP71(r) and they even made a 9mm conversion copy called the MP41(r).
 * With genuine enemy equipment often hard to come by, training units that simulate enemy forces often use friendly vehicles and aircraft painted - and sometimes structurally modified - to look like those of enemy forces.
 * During WWII the Russians trained dogs to run under tanks, the plan being to strap them with bombs and unleash them on the advancing Nazis. They lacked actual Nazi tanks to train with, however. When released in the field, the dogs performed exactly as trained and went under their own tanks.