A quarrel or bolt is the ammunition used in a crossbow. The name "quarrel" is derived from the French wordcarré, meaning square, referring to their typically square heads. Although their lengths vary, bolts are typically shorter than traditional arrows.
Parts of Crossbow bolt
A bolt consists of four main parts;
Shaft: It is main body of the bolt in which other parts of the bolt are attached. Shaft is normally made of carbon or aluminum and are very light weight, they don't bend or splint. However sometimes both aluminum and carbon are used. Shafts come with varying degrees of stiffness; that stiffness is referred to as the "spine" of the bolt. The more resistant to bending an arrow is, the more "spine" it is said to have. The weight of a shaft is in grains. Product descriptions may provide the total weight in grains or in grains per inch. The total weight of shaft can be calculated by multiplying the GPI value with length of shaft in inches.
Fletching: Fletching, also referred to as vanes, are wings that are located at the end of the shaft just before the nock. The fletching is made of plastic or other soft materials. They serves three main purposes; to stabilize the trajectory of the bolt mid-flight, help it keep going in the proper direction, and to prevent it from pitching or swaying to the left or right. Fletching may also cause the bolt to spin around its axis during the flight. There is no rule or formula for length of fletching, generally the longer the shaft is the longer fletching is and vice versa.
Point: The point, also called the head or the tip, is the front end of the bolt that is sharp so that it can penetrate the target.
Nock: A nock is a small object that is attached to the end of the shaft. It helps to keep the bolt in place. Nocks are made of either plastic or aluminum.
There is not any hard and fast rule of bolt sizing. Generally, the bolts are of 15 to 22 inches long but the standard length is 20 inches. Expertsrecommend longer bolts but they have certain disadvantages as well. The weight of bolt can have a serious effect on the range of the bolt. The bolt's total weight includes the bolt's weight, nock, insert, vanes, and broadhead or field point. Almost all bolt manufacturers will list how many grains each shaft weighs or how many grains are in each inch of the shaft. A more massive bolt, e.g. at least 400 grains, will have better downrange energy and offer better penetration, but will travel more slowly and thus drop more due to gravity during its flight. A lighter bolt will fly quicker and give the shooter a longer range, but might not have the desired penetration.
