4.5 mm vs 5.5 mm Air Rifles
Calibre identifies the bore and pellet diameter an air rifle is designed to use. Gamo.co.za lists rifles and pellets in both 4.5 mm (.177) and 5.5 mm (.22). Neither calibre is interchangeable, and the best choice depends on the exact rifle, intended practice and available pellets.
Core differences
| Comparison | 4.5 mm (.177) | 5.5 mm (.22) |
|---|---|---|
| Pellet diameter | 4.5 mm | 5.5 mm |
| Typical pellet mass | Generally lighter within comparable ranges | Generally heavier within comparable ranges |
| Trajectory | Can provide a flatter trajectory in comparable setups | Requires learning the trajectory of the exact rifle and pellet combination |
| Availability | Check current rifle and pellet stock | Check current rifle and pellet stock |
Do not compare calibre in isolation
Power system, barrel, pellet weight, sights, trigger, rifle weight and the user’s technique all affect results. Published velocity values may also use different pellet materials or weights, so they are not a complete cross-model comparison.
Match pellets exactly
A 4.5 mm rifle must use suitable 4.5 mm pellets and a 5.5 mm rifle must use suitable 5.5 mm pellets. Magazine-fed models can also have pellet-length restrictions. See the Gamo pellet guide and the exact product manual.
Current Gamo examples
The Gamo CFX audited for this guide is a 4.5 mm rifle. The Replay-10 and G-Magnum 1250 audited here are 5.5 mm configurations. Compare only the exact configuration shown on each page.
Use and safety
Follow the manufacturer manual, use suitable eye protection and a secure backstop, and treat every airgun as loaded. Owners are responsible for checking the rules that apply to possession and use in their location. This guide is product-selection information, not legal advice.
Reviewed by the Gamo South Africa product team on 25 August 2026.
