Airgun Ammunition by Calibre
Airgun Ammunition by Calibre: More Than Just the Right Size
Choosing the right airgun ammunition involves much more than selecting the correct calibre. The exact projectile diameter, weight and shape all influence accuracy, consistency and overall performance. Even small differences can have a noticeable effect on how an air rifle performs.
On this page you'll find airgun ammunition organised by calibre, while also learning why premium match pellets are available in different diameters, why projectile weight is measured in grains and how projectile shape affects ballistic performance.
Calibre is only the starting point
The calibre indicates the nominal diameter of the projectile and must always match the calibre of your airgun. Using the wrong calibre can reduce accuracy and may damage your airgun.
Our range covers virtually every popular calibre, from traditional 4.4 mm (.173) round balls to powerful .72 (18.3 mm) slugs designed for today's highest-powered PCP air rifles.
| Calibre | Inch | Common Projectile Types |
|---|---|---|
| 4.4 mm | .173 | Round Balls |
| 4.5 mm | .177 | Pellets, BBs, Slugs |
| 5.0 mm | .20 | Pellets |
| 5.5 mm | .22 | Pellets, Slugs |
| 6.35 mm | .25 | Pellets, Slugs |
| 7.62 mm | .30 | Slugs |
| 9 mm | .35 | Slugs |
| 11.4 mm | .45 | Slugs |
| 12.7 mm | .50 | Slugs |
| 15 mm | .58 | Slugs |
| 18.3 mm | .72 | Slugs |
Why are there different diameters within the same calibre?
Many shooters assume that a 4.5 mm pellet always measures exactly 4.50 mm. In reality, premium manufacturers often produce the same pellet in several head diameters.
Common examples include:
- 4.49 mm
- 4.50 mm
- 4.51 mm
- 4.52 mm
- 4.53 mm
The difference is only 0.01 mm, but that tiny variation can significantly affect how the pellet fits the barrel. Since every barrel has slight manufacturing differences, experienced target shooters often test several diameters to determine which one delivers the smallest groups and the most consistent velocity.
Match ammunition: precision starts with manufacturing
Competitive shooters demand extremely consistent ammunition. Manufacturers such as RWS produce premium match pellets with exceptionally tight tolerances in diameter, weight and shape.
This is why serious competitors often test multiple head sizes before selecting the pellet that performs best in their particular barrel. One rifle may produce its best groups with 4.51 mm pellets, while another performs better with 4.52 mm.
Budget ammunition for recreational shooting
Not every shooter requires match-grade ammunition. For practice and recreational shooting, brands such as Gamo offer reliable pellets at an attractive price. These products are manufactured with wider tolerances, making them ideal for general target shooting and regular training sessions.
If maximum precision is your goal, premium match ammunition will generally provide more consistent results.
Projectile weight: speed or stability?
Besides calibre and diameter, projectile weight is another important factor. Airgun ammunition is almost always measured in grains (gr), with one grain equal to approximately 0.0648 grams.
Every airgun performs differently depending on projectile weight. The ideal combination depends on factors such as power output, barrel length, rifling twist rate and muzzle velocity.
- Lighter projectiles generally produce higher muzzle velocities.
- Heavier projectiles usually retain velocity and energy more effectively over longer distances.
- A heavier projectile is not automatically more accurate.
- The ideal weight varies from one airgun to another.
Projectile shape influences flight characteristics
Shape plays a major role in ballistic performance.
- Wadcutter – flat nose designed for clean holes in paper targets.
- Domed (Round Nose) – the most versatile projectile for general shooting.
- Pointed – streamlined design for improved aerodynamics.
- Hollow Point – hollow-nose design for specialised applications.
- Slug – high ballistic coefficient, ideal for powerful PCP air rifles.
- BBs – steel or lead spherical projectiles for compatible airguns.
- Round Balls – traditional projectiles used in classic and historical airguns.
From 4.4 mm round balls to .72 slugs
SEM Jacht & Schietsport offers one of Europe's most comprehensive selections of airgun ammunition. Besides popular calibres such as .177 and .22, you'll also find specialised products including 4.4 mm (.173) round balls and heavy .58 and .72 slugs for today's most powerful PCP platforms.
Frequently Asked Questions
Why does one rifle shoot better with 4.51 mm pellets than 4.52 mm?
Every barrel is slightly different. Testing several pellet head sizes helps determine which diameter provides the best barrel fit and the tightest shot groups.
Why is projectile weight measured in grains?
Grains are the international standard for measuring bullet and pellet weight across the shooting industry.
Is a heavier projectile always more accurate?
No. Every airgun has its own preferred projectile weight. Testing different weights is the best way to determine what performs best.
Why are slugs so popular in PCP air rifles?
Slugs have a higher ballistic coefficient than traditional pellets, allowing them to retain velocity and stability over longer distances.
Can I safely use different pellet diameters?
Yes, provided they remain within the specifications for your calibre. Match pellet head sizes are specifically designed to help shooters optimise barrel fit and accuracy.
Why choose SEM Jacht & Schietsport?
SEM Jacht & Schietsport offers one of Europe's most complete selections of airgun ammunition. From affordable Gamo pellets to precision RWS match ammunition with 0.01 mm head size increments, and from traditional 4.4 mm round balls to powerful .72 slugs, we provide the right ammunition for virtually every airgun. Our technical expertise helps you choose the ideal calibre, projectile diameter, weight and shape for the best possible performance.
