What’s the Difference Between 4.5 mm and 5.5 mm Pellets?

Choosing between 4.5 mm and 5.5 mm pellets can be confusing, especially if you're new to air rifles. Although the difference in diameter is only 1 mm, the two calibres can behave quite differently depending on pellet weight, design, velocity and the air rifle being used.

So, what's the difference between 4.5 mm and 5.5 mm pellets? In general, 4.5 mm pellets are lighter and can achieve higher velocities with a flatter trajectory, while 5.5 mm pellets are usually heavier and can carry more momentum and energy downrange. Both calibres are widely used for target shooting, recreational shooting and, where permitted, hunting.

4.5 mm Pellets Explained

4.5 mm pellets are commonly known as .177 calibre pellets and are one of the most popular airgun pellet sizes. They are widely used for target shooting, recreational shooting and various field applications.

The smaller diameter and generally lighter weight mean that 4.5 mm pellets can often be propelled at higher velocities. This can give them a relatively flat trajectory, which is one reason why .177 remains particularly popular among target shooters.

That doesn't mean 4.5 mm is only a target-shooting calibre, though. There are many different 4.5 mm pellet designs available, including pellets intended for recreational and hunting applications where appropriate and lawful.

If you're looking for pellets in this calibre, browse our range of 4.5mm Pellets.

Advantages of 4.5 mm Pellets

• Generally lighter than 5.5 mm pellets
• Often capable of higher velocities
• Generally flatter trajectory
• Excellent choice for many target-shooting applications
• Available in a wide range of pellet shapes and weights
• Suitable for a variety of airgun applications when matched to the rifle

5.5 mm Pellets Explained

5.5 mm pellets are commonly known as .22 calibre pellets. They have a larger diameter and are generally heavier than 4.5 mm pellets of a similar design.

5.5 mm should not be thought of as simply a pellet for experimentation or casual shooting. It is a versatile calibre used for target shooting, recreational shooting and hunting with suitable equipment where lawful.

The heavier projectile can provide greater momentum and can retain more energy as it travels downrange. This is one of the reasons 5.5 mm is popular with shooters who want a combination of accuracy and greater impact potential.

There are also many different 5.5 mm pellet designs available, including domed, pointed and hollow-point options. The right design depends on the rifle, its power level and the intended application.

See our selection of 5.5mm Pellets to compare the available options.

Advantages of 5.5 mm Pellets

• Generally heavier than 4.5 mm pellets
• Greater momentum due to increased pellet mass
• Can retain more energy downrange
• Excellent choice for many recreational and field applications
• Widely used for hunting with suitable air rifles where lawful
• Available in a wide range of pellet shapes and weights

4.5 mm vs 5.5 mm: Quick Comparison

Both calibres can be highly accurate, but their typical characteristics are different.

4.5 mm Pellets

• Common calibre: .177
• Typical weight: Lighter
• Typical velocity: Higher
• Trajectory: Generally flatter
• Momentum: Generally lower
• Target shooting: Excellent choice
• Hunting: Used with suitable equipment where lawful

5.5 mm Pellets

• Common calibre: .22
• Typical weight: Heavier
• Typical velocity: Generally lower than a comparable 4.5 mm pellet
• Trajectory: Generally more pronounced
• Momentum: Generally higher
• Target shooting: Excellent choice
• Hunting: Widely used with suitable equipment where lawful

Which Pellet Does More Damage: 4.5 mm or 5.5 mm?

If you're comparing the two calibres purely in terms of impact potential, a 5.5 mm pellet will generally have the advantage when comparing suitable pellets from similarly powered air rifles. The larger calibre is normally associated with a heavier projectile, which can carry greater momentum and retain more energy downrange.

However, it isn't as simple as saying that every 5.5 mm pellet will cause more damage than every 4.5 mm pellet. Pellet weight, velocity, design and the power of the air rifle all have a major influence on performance.

A 4.5 mm pellet has the advantage of being lighter, which means it can often achieve a higher velocity. A suitable 4.5 mm pellet fired from an appropriately powered air rifle can therefore have significant impact potential.

When comparing otherwise similar setups, however, the heavier 5.5 mm pellet generally has greater momentum and can retain more energy as it travels downrange. This is one reason why 5.5 mm is so popular for applications where impact and energy retention are important.

Pellet design matters as well. Domed, hollow-point and other pellet profiles can behave differently on impact, so calibre should never be considered in isolation.

In simple terms: 4.5 mm generally offers higher velocity and a flatter trajectory, while 5.5 mm generally offers a heavier projectile with greater impact and energy-retention potential.

Does a Bigger Pellet Always Mean More Power?

No. A larger pellet does not automatically mean that an air rifle is more powerful.

Airgun performance depends on factors including pellet mass, velocity and the power of the rifle. Muzzle energy is particularly important when comparing different pellet and rifle combinations.

A lighter 4.5 mm pellet can often reach a higher velocity than a heavier 5.5 mm pellet. That is why simply comparing advertised velocity figures can be misleading.

On the other hand, the additional mass of a 5.5 mm pellet can give it greater momentum and help it retain energy downrange. The result is a trade-off between velocity and projectile mass.

Which Is More Accurate: 4.5 mm or 5.5 mm?

There is no universal winner when it comes to accuracy.

Accuracy depends on the individual air rifle, barrel, pellet design, pellet weight and shooting conditions. Two pellets of the same calibre can produce noticeably different results in the same rifle.

This is why experienced airgun shooters often test different pellet types rather than choosing a calibre based purely on advertised velocity.

4.5 mm is particularly popular for precision target shooting because suitable pellets can offer high velocity and a relatively flat trajectory. However, 5.5 mm can also be extremely accurate when the rifle and pellet are well matched.

Ultimately, the most accurate calibre is the one that produces the best results with your particular rifle and pellet combination.

Which Pellet Has the Flattest Trajectory?

Generally, a lighter 4.5 mm pellet will produce a flatter trajectory than a heavier 5.5 mm pellet when both are fired from the same air rifle.

This is one of the major advantages of 4.5 mm. A flatter trajectory means less pellet drop over a given distance, which can make aiming easier.

However, pellet shape and ballistic coefficient also matter. A well-designed heavier pellet can sometimes perform better in real-world conditions than a lighter pellet with less favourable aerodynamic characteristics.

Which Is Better in Wind?

Wind performance isn't determined by calibre alone.

A heavier pellet can carry more momentum, while pellet shape and ballistic coefficient influence how efficiently it travels through the air. This means a well-designed 5.5 mm pellet can perform very well outdoors.

At the same time, a quality 4.5 mm pellet can be extremely accurate in outdoor conditions. The best option depends on the specific pellet, rifle, distance and weather conditions.

Does Pellet Weight Matter?

Absolutely. Pellet weight can significantly change how an air rifle performs.

A lighter pellet generally accelerates more easily and can produce a higher velocity. A heavier pellet generally travels more slowly but carries more mass and momentum.

This is why simply looking at advertised velocity isn't enough. The fastest pellet isn't necessarily the most accurate, and the heaviest pellet isn't automatically the best choice.

The ideal pellet is the one that your rifle shoots accurately and consistently while providing the characteristics you need.

Which Is Better for Hunting: 4.5 mm or 5.5 mm?

Both 4.5 mm and 5.5 mm pellets are used for hunting applications with suitable air rifles, where hunting is legally permitted and the equipment is appropriate for the intended quarry.

5.5 mm is particularly popular because its heavier pellets can provide greater momentum and energy retention. This makes the calibre attractive to shooters looking for greater impact potential from a suitable air rifle.

4.5 mm should not be dismissed for field applications either. There are dedicated 4.5 mm pellet designs available for applications where their characteristics are desirable.

The important point is that calibre, pellet design and rifle power should all be considered together. For any hunting application, make sure you understand and comply with the applicable South African laws, provincial regulations and landowner requirements.

Which Is Better for Target Shooting?

Both calibres can be excellent for target shooting.

4.5 mm has traditionally been extremely popular because its lighter pellets can achieve high velocities and offer a relatively flat trajectory. Match-style 4.5 mm pellets are also widely available.

However, 5.5 mm can be very accurate too. A well-tuned rifle using a pellet that it shoots consistently can produce excellent groups regardless of whether the calibre is 4.5 mm or 5.5 mm.

If target shooting is your main priority, accuracy testing is more important than simply choosing the smaller calibre.

What About PCP Air Rifles?

PCP air rifles make the choice between pellet calibres particularly interesting because they are available in a wide range of power levels.

A powerful PCP rifle can make good use of heavier 5.5 mm pellets, while lower-powered rifles may be better matched to lighter ammunition. The manufacturer's recommended calibre and pellet weight should always be your starting point.

PCP rifles can also be pellet-sensitive. Changing pellet brand, shape or weight can change the point of impact and group size, even when the calibre stays exactly the same.

That is why testing different pellets can be useful. You're not simply looking for the highest velocity; you're looking for the combination that your rifle shoots most consistently.

Pellet Shape Matters Too

Calibre is only one part of the equation. Pellet shape can also have a noticeable effect on performance.

Common pellet designs include wadcutter, domed, pointed and hollow-point styles. Each design has different characteristics.

Wadcutter pellets are commonly associated with target shooting because they produce clean, easily visible holes in paper targets. Domed pellets are popular for general-purpose shooting and are available in many different weights.

Hollow-point designs are also available in both 4.5 mm and 5.5 mm and are commonly associated with hunting applications because their design can encourage deformation on impact.

The best pellet design depends on the rifle, its power level and the application.

Can You Use 4.5 mm Pellets in a 5.5 mm Air Rifle?

No. You should always use the calibre specified for your air rifle.

A 4.5 mm pellet is designed for a 4.5 mm airgun, while a 5.5 mm pellet is designed for a 5.5 mm airgun. Using the wrong calibre can result in poor accuracy, poor performance and potentially damage the equipment.

Always check the manufacturer's specifications before purchasing pellets. If you're unsure which calibre your rifle uses, check the markings on the rifle, its manual or confirm the model specifications with the manufacturer or a qualified dealer.

How Do You Choose Between 4.5 mm and 5.5 mm?

The right calibre depends on your rifle and what you want to do with it.

Choose 4.5 mm if:

• You primarily enjoy target shooting.
• You want a generally flatter trajectory.
• Your rifle is designed for 4.5 mm pellets.
• You prefer lighter pellets and higher velocities.
• You want a versatile calibre for target and recreational shooting.

Choose 5.5 mm if:

• You want a heavier pellet.
• You value greater momentum and energy retention.
• You enjoy target and recreational shooting.
• You have an air rifle designed for 5.5 mm pellets.
• You want a calibre commonly used for hunting where lawful and appropriate.

So, Which Is Better: 4.5 mm or 5.5 mm?

Neither calibre is simply "better" than the other. They have different strengths.

4.5 mm is an excellent choice when you want a lighter pellet, higher velocity and a flatter trajectory. It is particularly popular for target shooting but is also available in pellet designs intended for other applications.

5.5 mm is a highly versatile calibre in its own right. Its heavier pellets can provide greater momentum and energy retention, making it popular for target shooting, recreational shooting and hunting with suitable equipment where lawful.

If impact and energy retention are important considerations, 5.5 mm will generally have an advantage when comparing suitable pellets and similarly powered rifles. If flatter trajectory and higher velocity are your priorities, 4.5 mm may be the better fit.

Ultimately, the best pellet is the one that matches your rifle and the application you have in mind.

Final Thoughts

The difference between 4.5 mm and 5.5 mm pellets is about much more than a 1 mm difference in diameter.

4.5 mm pellets are generally lighter and faster, making them particularly popular for target shooting and applications where a flatter trajectory is useful. 5.5 mm pellets are generally heavier and can provide greater momentum and energy retention, which is why they are widely used for target shooting, recreational shooting and hunting with suitable equipment where lawful.

When it comes to which pellet does more damage, 5.5 mm will generally have greater impact potential when comparing appropriately matched pellets and rifles because of its greater projectile mass. However, pellet design, velocity, rifle power and accuracy all matter, so calibre alone doesn't tell the whole story.

If you're looking for 4.5 mm pellets, browse our 4.5mm Pellets.

If your air rifle uses the larger calibre, compare our selection of 5.5mm Pellets.

At the end of the day, matching the right pellet to your air rifle is more important than simply choosing the biggest or fastest option.