The Bisley Nylon Jag is a firearm cleaning attachment designed to hold cleaning patches while they are pushed through a barrel. It screws onto a standard cleaning rod and is available in different sizes to match specific calibres for rifles, shotguns, and airguns. Its main function is to provide a secure base for a cleaning patch so it can make full contact with the inside of the barrel during cleaning.

Unlike brass or steel jags, the nylon construction ensures there is no metal-to-metal contact with the barrel. This reduces the risk of scratching or marking the internal surface, making it especially suitable for users who prefer a softer, non-metallic cleaning method. Despite being softer in material, it is still strong enough to hold a patch firmly and maintain consistent pressure as it is pushed through the bore.

In use, the patch is wrapped or pressed onto the jag and then pushed through the barrel using a cleaning rod. As it travels through, the patch expands to match the bore and removes fouling, residue, and excess solvent. Multiple passes are often used during cleaning until the patches come out clean, indicating that the barrel is free of debris.

Nylon jags are commonly used in routine maintenance and are particularly popular for regular cleaning where gentler contact is preferred. They are durable, resistant to chemicals and solvents, and suitable for repeated use without corrosion or wear that can occur with metal alternatives.