What is the sprue of an arrow nock?

The sprue of an arrow nock refers to the small protrusion or extension that forms part of the nock's design, typically located at the back end of the arrow. It is often used to aid in the manufacturing process, particularly in molding, ensuring the nock retains its shape and can be easily removed from the mold. The sprue can also contribute to the structural integrity of the nock, although it is usually trimmed off or designed to be inconspicuous in the final product.