The HS-422 is one of the most durable and reliable servos Hitec has ever offered. With its dual iron-oilite bushings, high impact resin gear train and high performance circuitry, the HS-422 features excellent centering and resolution.
The answer to this question is partially dependent on what you are using to control the servo. 
Click for a quick video explanation.
With an Average Radio System:
87°
Your average transmitter and receiver will output a relatively narrow PWM signal range.
Radio System + Travel Tuner:
195°
Adding a Servo Travel Tuner to your radio system setup will allow you to achieve wide PWM signal ranges.
Wide Signal Controllers:
195°
Controllers such as the Servo Commander, Arduinos, and Raspberry Pi servo hats can usually send a wide signal.
| Output Shaft Style | C24T Spline | 
|---|---|
| Voltage Range | 4.8V - 6.0V | 
| No-Load Speed (4.8V) | 0.21sec/60° | 
| No-Load Speed (6.0V) | 0.16sec/60° | 
| Stall Torque (4.8V) | 45.82 oz-in. (3.3kg.cm) | 
| Stall Torque (6.0V) | 56.93 oz-in. (4.1kg.cm) | 
| Pulse Amplitude | 3-5V | 
| Operating Temperature | -20°C to +60°C | 
| Current Drain - idle (4.8V) | 8mA | 
| Current Drain - idle (6.0V) | 8.8mA | 
| Current Drain - no-load (4.8V) | 150mA | 
| Current Drain - no-load (6V) | 180mA | 
| Continuous Rotation Modifiable | Yes | 
| Direction w/ Increasing PWM Signal | Clockwise | 
| Deadband Width | 8µs | 
| Motor Type | 3 Pole Ferrite | 
| Feedback Style | 5KΩ Potentiometer | 
| Output Shaft Support | Dual Oilite Bushing | 
| Gear Material | Nylon | 
| Wire Length | 11.81" (300mm) | 
| Weight | 1.6oz (45.5g) | 
| Wire Gauge | 25AWG | 
| Servo Size | Standard | 
| Max Rotation | 195° | 
| Travel per µs | 0.0975°/μsec | 
| Max PWM Signal Range | 500-2500μsec |