What is a single action only revolver? What visual clues might you have with this type of action?

What Is a Single-Action-Only Revolver?

A single-action-only (SAO) revolver is a type of revolver that cannot be fired until the hammer is manually cocked by the shooter. In this design, the trigger only performs one function — releasing the hammer to fire the gun — and does not cock the hammer itself. This means the shooter must thumb back the hammer before each shot.

How to Recognize a Single-Action Revolver

Visual and loading cues help identify a single-action revolver:

• Side loading gate: Many classic single-action revolvers have a loading gate on the side of the frame. The user opens this gate and loads or unloads cartridges one at a time while rotating the cylinder manually.

• Top-break or frame-swing loading: Some designs (less common) allow the frame to open or pivot forward (top break), which also permits loading and unloading one chamber at a time.

• No typical cylinder release latch: Unlike many double-action revolvers with a left-side cylinder release that lets the entire cylinder swing out, traditional single-actions often rely solely on a loading gate and cylinder rotation by hand rather than a release latch.

Mechanical Simplicity and Trigger Function

A single-action revolver generally has fewer internal connections and moving parts compared with a typical double-action revolver. This simplicity arises because:

• The trigger’s only job is to release the hammer — it does not cock it. That means fewer linkages and springs are involved in the firing cycle.

• In contrast, a double-action mechanism uses additional parts (such as a longer trigger travel, hammer cocking linkage, and mainspring setup) to both cock and release the hammer with one trigger pull.

• The simpler action in SAOs often translates to a lighter and smoother trigger pull since the trigger is not doing the hammer-cocking work.

Trigger Springs and Mechanism Notes

Your statement about trigger springs can be clarified like this:

• Single-action revolvers typically rely on a mainspring directly linked to the hammer rather than complex intermediate springs found in some double-action systems. This contributes to mechanical simplicity. While some older designs may use a bar-type spring as part of the mechanism, modern designs vary and often use coil springs depending on manufacturer and model.

• Double-action revolvers require additional spring tension and parts to let the trigger cock and release the hammer as part of a single motion — which adds complexity compared with a single-action system.

Summary of Key Differences

Feature	Single-Action Only	Double-Action
Trigger Function	Only releases a manually cocked hammer	Cocks and releases hammer (or just releases if already cocked)
Loading Style	Side loading gate or hinged frame, one at a time	Typically swing-out cylinder with latch
Mechanical Simplicity	Fewer moving parts	More linkages & springs
Trigger Pull	Light and crisp	Longer/heavier when used in double-action mode

Cited References

• Single-action mechanism and firing operation explanation — revolver must be cocked manually.

• Standard loading gate and single-action loading procedure.

• Typical revolver loading gate and visual cues.

• Explanation of trigger duty and differences between SA and DA.

• Confirmation of alternative loading styles and common traits.

• Comparison of internal parts and mechanical simplicity.