Parts of a Crossbow – All You Need to Know About Crossbow Anatomy

Whether you are an experienced bowhunter or a beginner, you need to understand the various parts of a crossbow. Doing so will enable you to optimize your equipment to meet your needs, increase your accuracy and precision and ultimately enjoy a far more engaging and fun experience.

If you’re just starting bowhunting, first research the regulations set by your state and ensure that the equipment in your collection matches the region’s specifications. No matter what your experience level, safety should always be your number one priority, and understanding the anatomy of your crossbow will be key to maximizing safety.

To help us understand the anatomy of a crossbow, we are going to use the Killer Instinct Lethal 405 Crossbow as an example. You can get yourself one of these seriously deadly machines on Amazon, check it out below!

Parts of a Crossbow – The Main Body

At first glance, crossbows may just seem like a horizontal mounting of a vertical bow with a frame attached to allow its user to fire it, but it’s much more complicated than that. You will find many similar components and features on crossbows and conventional bows, they are all put together in a very different way and modern innovations continue to widen the gap between regular bows and crossbows with each new idea.

Due to its complexity compared to vertical bows, you should first understand the terms used to describe parts of a crossbow as learning a crossbow’s anatomy helps you understand how to use it safely, accurately, and for different purposes.

With that, here is a detailed compilation of the parts of a crossbow. The image below will help you to locate and understand each part as your work through the list. We’ll start with the back end the crossbow before we work towards the business end at the front.

1 & 2. String and Serving

The string or bowstring (1) is the part of the rope-like tension cables that lies above the rail (central channel of the crossbow) and spans between the tips of the limbs (the curved “arms” of the crossbow). Each end of the string threads through cam wheels located on the limbs (unless you’re talking about a medieval crossbow, where the string was attached directly to a limb).

The part of the string which then feeds back out of the cam wheels, overlapping as it crosses underneath or through the crossbow stock, is referred to as the cables. This is part of the cam system and is designed to store incredible amounts of power relative to the amount of energy required to load the crossbow. More on cam systems later.

The middle of the string which gets held in the trigger box (more on this later too) where you load the crossbow bolt is typically thicker and wrapped in another string-like material. This is called the serving (2). The serving protects the most used part of your strings from wearing out.

As you load the crossbow, you draw back the string which loads the serving into the trigger box. Energy builds up and is stored in the string, ready to bounce back like a spring. Once you load a bolt and pull the trigger, the energy transfers into a crossbow bolt, sending it rocketing off at high speed.

Bowstrings from back in the day used animal sinew, linen, or even hair, but today, almost all strings are synthetic materials. These are flexible, durable, lightweight, and have a much lower level of “creep” (stretching over time). The strings/cables and the serving use different materials.

For suitable synthetic fibers to use as bowstrings, look for polyester (Dacron), High Modulus PolyEthylene or HMPE (Dyneema, Dynaflight 97, 8125G, Mercury, etc.)  or HMPE/Vectran blends (452X, BCY-X, Trophy). If you have a steel cabled crossbow, use Dacron strings as you’ll need extra flexibility. Otherwise, use HMPE.

Serving synthetics use similar materials but with a different level of elasticity and durability. Look for Angel Majesty .036, 62XS, Powergrip, or Halo serving materials. With both bowstring and serving materials, beware of cheap knock-offs. Try to get the real deal, with anything from BCY being a safe bet.

3. Stock / Butt

The stock (3) lacks any mechanical purpose, but it remains an essential feature on your crossbow. It is essentially the bones of your crossbow, connecting the trigger, latch, rail, limbs, riser, and other crossbow parts.

A crossbow’s stock also includes the butt of the crossbow, the large part at the base of the crossbow which you use to “shoulder” the weapon.

The stock makes up a significant part of the crossbow. When made from the wrong materials or poorly designed, the crossbow stock can become heavy and overbearing. Most modern crossbows use cast aluminum, aluminum alloys, or synthetics such as molded plastic or carbon fiber. On occasion, you can still find wooden stocks similar to those used in medieval times.

Weight and durability are your primary concerns here. Without a doubt, you should be looking for a skeletonized stock and butt. “Skeletonized” means that the stock is not a solid piece but has sections cut out to remove weight. You will also often see large holes drilled through the stock for further weight reductions without impacting strength.

4 & 5. Rail and Bolt Retention Spring

A crossbow’s rail (4 – also called barrel or track) is the upper central shelf of the bow where the bolt sits once the crossbow is cocked. Modern crossbows include a flight groove (aka bolt track or flight track) that acts like a firearm’s barrel from which a projectile is shot. It is long and firmly attached to enhance the bolt’s speed and the accuracy of your shot.

At one end, you’ll see the opening between the limbs that the bolt shoots through, and at the other end is the latch (a mechanism that holds the string when the crossbow is cocked and pulled back).

Within the channel of the rail is a component called an arrow retention spring (5). This also helps to hold the bolt in place as it passes along the rail in the mere milliseconds between pulling the trigger and exiting the riser. Without an arrow retention spring, your bolt is likely to fall from the rail if you aren’t holding the weapon perfectly level.

The combination of your crossbow rail and arrow retention spring is critical. It ensures your crossbow bolt remains still until you choose to fire it. The rail then creates a guide as the trigger box releases the string and transfers its energy to the bolt, allowing your bolt to fly true, with much greater precision. Depending on the arrangement of the bolt fletching at the back of the bolt, you may need to load your bolt at a certain angle to prevent damaging it and maintain a high degree of accuracy.

You want lightweight, narrow, and durable rails with an in-built arrow retention spring.

6, 7 & 8. Foregrip, Hand Guard and Pistol Grip

When operating your crossbow, the stock’s butt remains pressed against your shoulder. While the crossbow remains on your trigger hand, your front hand (or post hand) operates the foregrip (6), a feature found under the rail. The foregrip maintains a proper and steady position as you aim at the target, improving shot consistency and precision.

Foregrips for crossbows typically have a horizontal profile, but you can install aftermarket grips with a vertical style that is reminiscent of shotguns or machine guns. Generally speaking, though, horizontal foregrips are best, and you may want to practice shooting with the crossbow resting on the foregrip rather than grabbing it to help you learn to relax as you shoot and lead to greater accuracy.

Another alternative is to use a monopod otherwise known as a shooting stick. You can rest the foregrip of your crossbow in the monopod to remove almost any shakiness you may be bringing to the bow when aiming. Check out this one if you’re interested!

Once your pull the trigger, the string will rocket forward, propelling the bolt at insane speeds. If your finger or hand happened to be in the way of the string, it would cause some serious damage. Luckily, most modern crossbows come with a hand guard or shelf (7) installed, protecting you from any unwanted surprises!

With the stock pressed up against your shoulder and your post hand on the foregrip, your other hand (or trigger hand) will be on the pistol grip (8), located near the trigger. This grip looks much more like a gun grip, hence the name and is usually very ergonomic to allow your to comfortably hold the crossbow as you silently aim and pull the trigger.

9. Trigger

As the name suggests, the trigger (9) is what you pull when firing your weapon. Crossbow triggers loosen the latch, pushing the bowstrings forward and releasing the bolt, shooting it towards the target.

Different crossbow brands have varying trigger positions. Some are placed in front of the latch, while others are below it.

A few things are important when considering your trigger. The first is sensitivity. A highly sensitive trigger will require very little pressure to send the bolt soaring. This might seem prone to unplanned shots, but remember, you will (or at least should!) always have your safety on when you’re not ready to shoot.

The advantage of a hair-trigger, as super sensitive triggers are called, is that pulling the trigger will have almost no bearing on your aim. Heavier triggers may slightly skew your aim as you pull. That quarter of a millimeter shift as you pull the trigger could translate to an inch by the time it reaches your target, and be just enough to miss the kill shot.

Your second consideration is noise. High-quality triggers will make no noise when the latch is triggered, giving your target no chance to hear you and instinctively dodge.

10. Trigger Box / Latch

Unlike conventional bows, crossbows can be cocked to store all the energy of the draw well before you make the shot. The mechanism that holds the string in place to store this energy is known as the latch or trigger box (10). This also contains the crossbow’s safety mechanism, so it’s very important!

Your priorities here will be durability and noise. Although possible, it would be unusual to do an aftermarket latch upgrade. Look for quality brands that have paid attention to the trigger box and optimized it.

11 & 12. Scope / Sight and Sight Bridge

Crossbows bolts require extreme precision to humanely take down their target. Although you typically only shoot crossbows within a fifty yard range, arguably even within a 40 yard range. This close proximity helps with accuracy but even just an inch or two off or difference can be the difference between a clean kill and failure.

Scopes and sights are therefore a critical accessory for crossbows, as they allow for a greater degree of precision and accuracy. Some also come with built in angle and distance compensation to correct for the sight’s reticle and improve your accuracy and consistency at longer distances or when shooting from tree stands. Without these features you will likely need to learn to adjust your crossbow scope on the fly.

Crossbows don’t always come with a sight or scope pre-installed but they will often include an area to mount one. This is referred to as the sight bridge and comes in a few different styles. The most common is the Picatinny rail, which is a specially designed system for installing various accessories on to crossbows and firearms.

If you crossbow didn’t come with a sight or the one it did come with is not up to scratch, check out our guide on the best crossbow scopes or take a look at this great option below!

13. Cocking Stirrup

A key differentiator between conventional bows and crossbows is their raw power, being capable of shooting bolts with lethal precision at over 400 fps. This power demands a higher force to draw the string, otherwise known as cocking the crossbow. This is where the cocking stirrup (13) or foot stirrup comes in.

The cocking stirrup is used to place your foot in and firmly hold the crossbow in place while your cock it either with your bare hands or with a rope cocker. The process is reasonably easy, but is definitely worth learning how to do it properly before trying it yourself, as it does require a reasonably amount of strength. Our guide on how to cock a crossbow is a great starting point!

Rope cocking will reduce the effort required by about 50% relative to cocking manually. You can also cock your crossbow with a crank system, which negates the need for a cocking stirrup altogether and can reduce effort by as much as 90%!

Stirrups are quite common on modern crossbows, but more modern designs include step-through risers, which basically integrate the cocking stirrup into the riser of the crossbow (see below) and make a shorter profile, more balanced and lighter weight crossbow. The Barnett Whitetail Hunter STR shown below is the iconic example of the step-through riser design.

Parts of a Crossbow – The Front End Assembly

Now we move on the the front end assembly (14). There’s a lot going on here, so we’ve got another diagram to help make things easier. Again, this is based on the Killer Instinct Lethal 405 Crossbow, so it carries on from the last illustration.

1. Limbs

Limbs (1) are a vital part of your crossbow. These are the curved parts that frame the front of the crossbow. The limbs often bend slightly backward at their extremities, this design is known as a recurve crossbow as the limbs “recurve” on the ends.

Each limb’s branch on olden-day crossbows would attach to the crossbow string’s end. Modern crossbows almost all have cam systems installed, similar to a compound bow, with the cam wheels being located at the end of the limbs.

They are constructed from strong, flexible materials such as carbon fiber, aluminum, or certain woods, enabling the limbs to bend when you pull back the strings, storing energy as the crossbow is drawn. If constructed from poor materials, limbs may break when you pull them backward, so quality limb construction is a must!

When you pull the trigger, the limbs instantly flash forward and use the stored energy to launch them forward. The speed depends on the draw weight and length of the crossbow. You can adjust these on some models, but it is not an option with most.

2 & 3. Riser and Limb Bolt

The riser (2) creates a connection between the limbs and other parts of your crossbow. It is a single piece that holds both limbs and provides a space between them to facilitate the firing of a crossbow bolt. The limbs are secured to the riser by a limb bolt (3).

The riser deals with a massive amount of pressure every time a bolt is fired. It should be made of strong, lightweight materials to withstand this shock but remain easy to handle. Aluminum that has undergone casting to strengthen it is common, but carbon fiber is becoming more prevalent.

The risk of breaking your riser is one of the reasons a crossbow should never be dry fired (fired without a bolt loaded).

Some crossbows also offer a take-down riser feature. This allows the user to quickly deconstruct (and reconstruct) the crossbow by removing (replacing) the limbs, usually with thumbscrews.

Risers may also come with mounting slots to add attachments such as the bolt quiver or foot stirrups (used for loading the crossbow). You may also see step-through riser designs that effectively combine the foot stirrups and riser into one single piece.

4 & 5. String Stoppers and Limb Dampeners

The string stoppers (4) do just that. There job is to stop the string when it flings forward as you pull the trigger. The major challenge here is noise. The tension on the string makes it accelerate incredibly fast when released and without quality string stoppers the crossbow would be very loud when firing, alerting your prey to your presence and giving them a few milliseconds to react and ruin your shot.

Limb dampeners (5) are designed for a very similar purpose. They prevent the limbs from shaking around wildly when the crossbow is fired, reducing the noise in the shot. They also reduce any loss of energy through the bow by reducing unnecessary vibration and shaking in the limbs. The less energy lost through the crossbow, the more power than will be transferred from the string to the bolt to deliver serious speed and damage.

There are other attachments that can be added to the bow that further reduce noise and energy loss. These are known as noise dampeners or recoil dampeners and can also be added to the string, bolt retention spring, stirrups and rail. Below, you can get the whole lot in one easy package!

6, 7 & 8. Cam Wheels, Cam Anchor Pulley and Cables

The cam system is the combination of the cam wheels (6) at the end of the limbs, the cam anchor pulleys (7) or cable anchors which secure the cables to the top of the cam wheels, and the cables (8) or strings that wrap around the cam wheels and cross underneath the stock.

The cam wheels come in oval or round shapes, acting as pulleys for your crossbow. As the crossbow is cocked, the cam wheels turn, allowing a significant amount of power to be stored within the string of the bow despite the compact design. Once fully drawn, the latch holds the serving, and the cam system helps reduce strain on the limbs and stock.

Pulley systems reduce the effort required to build up kinetic energy, storing it within the bowstrings. The cam systems also help keep the crossbow string balance, aligned, and in sync through the draw cycle for increased precision.

You cannot change out or replace the cam system on a crossbow. It’s too heavily integrated into the design. So, the cam system is a key feature in the crossbow you select. It is one of the key pieces contributing to the draw weight, speed, and power of your crossbow.

It’s worth noting here that reverse draw crossbows are now available. Although it is part of the overall design, the cam system is a key enabler for reverse draw models. These crossbows have the limbs facing in reverse and offer a much narrower and lighter build. They also boast less noise, higher precision, and greater balance. Worth keeping your eyes peeled for one of these!

We’ve Covered The Parts of A Crossbow, So What Now?

It’s time to take a shot! One of the best feelings is releasing a bolt and getting your first bullseye or perfect shot during practice. After learning how each crossbow part works, you’ll become more comfortable with your gear, relaxing, and finding the focus needed to get your aim just right.

You’ll learn how to adjust, tune and hone your setup to improve your game, understanding how to use each component to start shooting and hunting with more confidence.

But don’t stop there! There’s always more to learn. Even if you’re a seasoned hunter or archer, practice and study of the sport will always help to improve your skills. Perhaps you need to learn the perfect place to shoot a turkey, how to hunt from ground blinds, or the feeding habits of deer to improve your stalking.

So what are you waiting for!? Get reading, get your crossbow, get hunting and get that trophy!