In drilling fluid solids control, a mud gun is a device used to mix and agitate drilling mud in mud tanks, particularly in corners and hard-to-hard areas where agitators are less effective. It uses a high-pressure jet of mud to suspend solids, prevent settling, and ensure the drilling fluid remains homogeneous. 

Function and working principle
Mud guns are a vital part of the solids control system, working in conjunction with mud agitators to keep the drilling fluid properly mixed and in circulation. 

• Preventing solids from settling: By directing high-speed fluid jets towards the tank's bottom and corners, mud guns break up sediment and keep solid particles suspended. This is crucial for maintaining the properties of the drilling mud, such as its viscosity and density.
• Cleaning the tank: A mud gun can be used to flush and clean accumulated mud and solids from the bottom and walls of a mud tank.
• Transferring mud: The gun can also be used to facilitate the transfer of drilling mud from one tank compartment to another, for example, to a trip tank.
• Assisting agitators: While mud agitators work to mix the fluid in the center of the tank, mud guns reach the "dead spots" or tank corners that the agitators cannot reach effectively. 

• Based on mounting and structure:
  • Fixed mud gun: A stationary mud gun designed for a specific coverage area in the tank.
  • Rotary (or swivel) mud gun: This type is designed to rotate, often up to 360 degrees, to provide complete mixing coverage within the tank without blind spots.
  • Bottom-type mud gun: Installed at the bottom of the tank, this design is simple and effective for large metal tanks.
  • Spinner/pivot-type mud gun: A rotating type where the nozzles are angled to create a spinning motion from the fluid pressure. 

• Main body: The primary pipe assembly that connects to the mud line.
• Nozzles: The discharge ports where the high-pressure fluid exits. For durability, they are often made from wear-resistant materials such as polyurethane or tungsten carbide alloy.
• Adjusting handle (for rotary type): Allows the operator to change the direction and angle of the high-pressure jet.
• Flange: Used for connecting the mud gun to the drilling mud tank's mud line. 

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