text: Denied, Degraded and Disrupted Operations
  C-36. This method of lay is used during a deliberate occupation when an aiming circle is not available. The
  M2 compass is used to lay one howitzer. Once laid for direction, that howitzer is used to reciprocally lay the
  remaining howitzers.
  C-37. The steps for laying with the M2 compass are as follows:
  * Place the M2 compass on a stable object (such as a collimator cover, and aiming circle tripod, or
  a mattock handle) away from magnetic attractions.
  * Measure the azimuth to the pantel of the howitzer to be laid.
  * Determine the deflection to the howitzer by subtracting the azimuth of fire from the measured
  azimuth.
  C-38. This method of lay has advantages and disadvantages that must be considered before it is used.
  * The main advantage to using this method is that all howitzers will be oriented parallel.
  * Disadvantages are the compass is graduated every 20 mils and can be read to an accuracy of 10
  mils. The accuracy depends a great deal on the ability of the instrument operator.
  Note. A mil is a unit of measure for angles that is based on the angle subtended by l/6400 of the
  circumference of a circle (TC 3-09.81). The mil is used because of its accuracy and the mil relation
  formula, which assumes that an angle of one mil will subtend an arc of one meter at a distance of
  1,000 m. The graphic representation of a mil is a lower-case letter "m" with a virgule (/) through
  it.
  MEASURING AN AZIMUTH USING AIMING POINT-DEFLECTION METHOD
  C-39. The aiming point-deflection method of lay is used during an emergency fire mission when the need to
  expedite the mission is more critical than the need for first-round accuracy. A distant aiming point is required
  and must be at least 1,500 m from the position. All howitzers must be able to pick up a line of sight to the
  distant aiming point. A compass, or a map and protractor are the only equipment needed. For more
  information on measuring an azimuth using an aiming point-deflection method see ATP 3-09.50.
  MEASURING AN AZIMUTH USING COLLIMATOR AND AIMING POSTS
  C-40. The collimator is the primary aiming point for the howitzer. The emplacement distance for the
  collimator will vary because of terrain encountered but is normally between 4 and 15 m from the howitzer.
  Displacement is corrected by matching the numbers in the panoramic telescope with the corresponding
  numbers in the collimator. If the collimator is not emplaced within the distances stated above, the graduations
  visible in the collimator will not align properly and the sight picture will be out of focus. Therefore, it will
  be impossible to correct for displacement.
  C-41. The aiming posts are a secondary aiming point for the howitzer. The aiming posts are emplaced
  approximately 50 and 100 m from the gun for the M119-series and M109-series howitzer, or 75 and 150 m
  for the M777-series howitzer. The increased spacing of the M777-series howitzer's aiming posts is due to the
  pivot point of that weapon system. When firing out of traverse missions, the gunner can lose sight of the
  aiming posts at the shorter distances. Increasing the distance of the aiming posts addresses the problem. For
  more information on measuring an azimuth using the collimator and aiming posts see ATP 3-09.50.
  MEASURING AN AZIMUTH USING THE RECIPROCAL LAYING METHOD
  C-42. Reciprocal laying is a procedure by which the 0-3200 line of one instrument and the 0-3200 line of
  another weapons on the azimuth of fire. The aiming circle is used to measure horizontal clockwise angles
  from the line of fire instrument are laid parallel.
  C-43. The aiming circle is the primary means by which the cannon battery orients weapons on the azimuth
  of fire. The azimuth of fire is the direction, expressed in mils, that a fire unit is laid (oriented) on when it
  occupies a position (ATP 3-09.50). The aiming circle is used to measure horizontal clockwise angles from