(Editor’s Note: If you’re new to the Kalashnikov platform this AK-47 FAQ and glossary will be helpful.)
Q: What are the main AK-47 variants?
A: They include:
- AK: An early AK-47 variant which had a receiver machined from a solid block of steel. AK refers to Avtomat Kalashnikova or “Kalashnikov automatic rifle,” where 47 equals 1947–the year the firearm was first manufactured.
- AKM: (Avtomat Kalashnikova Modernizirovanniy or “Kalashnikov modernized automatic rifle”) is the more modern version of the original 7.62mm AK-47. Its stamped, riveted sheet metal receiver is much lighter and less costly, and more expedient to manufacture. Most of the modern-day AK variants are essentially AKM-style rifles.
- AKMS: This version has a pressed steel receiver (like the AKM) with a down-folding butt stock. It’s intended for paratroopers and other situations in which the rifle needs to be more compact.
- RPK: This is a Kalashnikov with a reinforced receiver, lengthened barrel and bipod to serve as a squad automatic weapon. The RPK is manufactured as a semi-auto rifle for civilians by Molot as a VEPR.
Q: What’s the difference between an AK-47 and an AK- 74?
A: The AK-47 is chambered in 7.62×39 whereas the AK-74 uses the 5.45×39 round.
Russia altered the Kalashnikov design in 1973 by taking the lead of the U.S. armed forces to accept a smaller, high-velocity bullet. The re-chambered design was inaugurated in 1974 and dubbed the “AK-74.”
The long 60-grain 5.45mm bullet is meant to be unstable upon hitting a solid object, so that it will twist or oscillate violently, generate greater hydrostatic shock, and tear a larger wound cavity.
The AK-74 has four major variants: the standard fixed stock version, the folding stock version, the RPK-74, and the “Krinkov” submachine gun.
The AK-74 has less recoil and the 5.45mm bullet has a flatter trajectory than the 7.62×39 round can provide for more accuracy at a longer distance.
Q: What’s a Krinkov?
A: A short barreled AK that can be chambered for 7.62×39 as well as 5.45×39 or other calibers.
Q: What’s a VEPR?
A: The VEPR is based on the RPK, an AK-style light machine gun and hence is heavier than an AK. Its receiver is thicker and it has beefier locking lugs. The bull barrel can provide for more accuracy at long distances.
Q: What’s the thread pitch on an AK-47?
A: It is LH (left handed) 14x1mm.
Q: What’s the thread pitch on an AK-74?
A: It’s 24X1.5mm RH (except for Romanian) which is 22X1.5mm RH.
Q: What is a Shepard’s hook?
A: It’s a retaining spring meant to hold the hammer and trigger pins in place. It’s much better to replace it with a retainer plate, which serves the same function but allows for easier assembly of the trigger group.
Q: What is a Sporterized AK?
A: Some AKs, such as the Saiga line, were imported from Russia for “sporting purposes” in the form of a hunting rifle. They still have major AK components such as the receiver and barrel, but do not incorporate any of the features typically associated with so-called “semi-automatic assault weapons” (Chapter 27 of the Code of Federal Regulations Section 478.11 defines these “SAWs”).
Examples of these features include:
- “High capacity” magazines (greater than 10 rounds for rifles or five rounds for shotguns).
- Pistol grip attachment.
- Folding buttstock.
- Muzzle device/attachment (to include a threaded barrel capable of receiving a device).
- Bayonet lugs.
If your rifle or shotgun includes those features, it no longer is considered by BATFE “suitable for sporting purposes.”
Q: Are AK parts interchangeable with other AK variants?
A: Usually parts such as gas tubes, the bolts and carriers and trigger groups are interchangeable. But don’t bet on it. Every AK variant has different specs, so often you cannot interchange parts between different manufacturers. (See interview with Marc Krebs in Chapter 3, who discusses this in depth).
Q: What does “co-witness” mean?
A: It’s not a religious experience, although for AK users, it’s a kind of a holy grail.
A “co-witnessed” set of sights means that you’re properly able align your iron sights so that the point of aim of the red dot will line up precisely with the point of aim of the iron sights. Thus, when you have your iron sights up, you’re able to position the red dot floating above the front sight post.
(Our friend Dmitri at Primary Arms did a very good video on co-witnessing).
Q: Are all AK magazines interchangeable?
A: Not all, but most AK variants accept all standard AK-47 magazines. There may be tolerance variations that may cause issues in some guns. For example, the locking tabs can be thicker and at different angles.
Q: Will replacement furniture for a stamped receiver fit a milled receiver?
A: No. The milled receiver is thicker and furniture designed for stamped receivers will not fit.
Q: What is doubling?
A: Doubling is when the rifle fires more than one shot with a single pull of the trigger, and the rifle is not equipped for full auto fire.
Sometimes the shooter may discover the hammer resting on the firing pin (released or fired position) on a loaded chamber. Pulling the bolt carrier back far enough to reset the hammer will often result in a successful discharge.
Q: What size barrel is standard for an AK?
A: The standard size is 16 inches. There are longer barrels available, and sometimes the standard barrel is cut and shortened.
Q: What’s an SBR?
A: A short-barreled rifle (SBR) is a legal designation in the United States, referring to a shoulder-fired, rifled firearm with a barrel length of less than 16 inches (40.6 cm) or overall length of less than 26 inches (66.0 cm).
Q: What’s a trunion?
A: The rear AK-47 trunion both holds the receiver and the stock in place. This part also has a channel to fit the recoil assembly, which both locks into that passage and snaps the receiver cover in place.
The front trunion holds the barrel to the AK-47 receiver and holds the receiver together. It also helps hold the rear sight block. The two lower holes are for rivets through the receiver; the hole up top is for the barrel pin.
Q: Does the AK-style rifle have a “bolt hold open” function similar to an AR?
A: AKs do not utilize this mechanism.
Q: Can a “bolt hold open” mechanism be installed?
A: Yes, but it would require some gunsmithing.
Another option is to purchase magazines that will perform this function. Note that the feature will work only so long as the empty magazine is left in the rifle. Once removed, the bolt will slam shut, unless some additional mechanical provision (such as a slotted safety arm) is provided to keep it open.
Q: What is a Bullet Drop Compensator (BDC)?
A: A Bullet Drop Compensator (BDC) is a feature available on the reticle of some rifle scopes that helps the shooter estimate vertical point of aim offset required for the effect of gravity on the bullet at given distances on level terrain. These consist of extra marks along the bottom post to line up your shot.
The best BDC reticles are engineered to conform to a ballistic curve — the arc of a bullet as gravity pulls it earthward.
Q: What is a Picatinny rail?
A: The Picatinny rail, also known as a MIL-STD-1913 rail or tactical rail, is a bracket that offers a standard mounting platform for optics and other accessories. The rail consists of a series of ridges with a T-shaped cross-section interspersed with flat slots.
Q: Are AKs the most reliable rifle in the world?
A: They probably are. To quote Rick Davis: “The Kalashnikov rifle is so reliable that failures of any kind are generally a curiosity and regarded as a rare event.”
Q: Is it true that I never need to clean my AK-47?
A: While the AK-47 has a well-deserved a reputation for reliability, it should still be cleaned on a regular basis. This will ensure proper function and accuracy. Note that any rifle (including the AK), must be cleaned after firing corrosive ammunition, or the effective service life of the rifle will be very, very short, indeed.