A bow plunger, also known as a cushion plunger or button, is a spring-loaded device attached to the riser of a recurve or traditional bow. Its primary function is to provide adjustable resistance to the arrow as it leaves the bow, helping to compensate for the arrow's sideways flex (archer's paradox) and ensure a clean, straight launch.
The Mechanism Explained
The core of a bow plunger is a pin that extends through the arrow rest window of the bow riser. This pin is backed by an internal spring.
- Spring-Loaded Pin: The pin moves inward against the spring tension when pressure is applied.
- Mounting: The plunger screws into a threaded hole in the bow riser, typically above the arrow rest mounting hole.
Role in Arrow Flight (Archer's Paradox)
When an archer shoots a recurve bow, the arrow doesn't just fly straight off the string. Due to the force of the string pushing from behind center and the archer's grip, the arrow flexes sideways around the riser. This phenomenon is known as archer's paradox.
The bow plunger plays a crucial role in managing this flex:
- As the arrow accelerates forward, it bends towards the riser.
- The side of the arrow shaft presses against the plunger pin.
- The spring in the plunger allows the pin to give way slightly, cushioning the arrow's movement towards the riser.
- This controlled give allows the arrow to "snake" past the riser cleanly without colliding hard against it, preventing erratic flight.
Without a plunger, the arrow would likely slap against the riser during paradox, disrupting its path.
Adjusting Center Shot and Tuning
One of the key benefits of a bow plunger is its adjustability, which is critical for tuning the bow and arrow combination. As mentioned in the reference, adjusting the center shot on your plunger is possible, and "they all work pretty much the same."
- Spring Tension: This is typically adjusted by screwing or unscrewing a cap at the back of the plunger body.
- Increased Tension: Provides more resistance, making the arrow flex less against the riser. Useful for stiffer arrows or higher poundage bows.
- Decreased Tension: Provides less resistance, allowing the arrow to flex more against the riser. Useful for weaker arrows or lower poundage bows.
- Pin Extension: This is the distance the pin extends from the plunger body. Adjusting this sets the resting position of the arrow relative to the center of the bowstring (the center shot).
- Adjusting the pin extension moves the arrow rest position left or right (for a right-handed shooter). This is a fundamental tuning step to ensure the arrow is aligned correctly for optimal flight.
By adjusting both the spring tension and pin extension, archers can fine-tune their setup to match the arrow's spine (stiffness) to the bow's draw weight and their shooting form, achieving consistent, accurate arrow flight.
In essence, the bow plunger acts as a flexible side plate that guides the arrow cleanly through the paradox phase, and its adjustability allows for precise tuning of the arrow's launch angle and flight characteristics.
