The U.S. Marine Corps developed the mil-dot reticle in the late 1970s as a means for the Marine sniper to estimate distances. Today, the mildot represents the standard approach for range estimating by both military and law enforcement in conjunction with laser rangefinders. A detailed review of the logic of design, types of mildots and the actual utilization of the mil-dot reticle can be found in a number of recent articles and books on sniping (l-5) and will not be reviewed here.
Mil-dot reticles are offered by several scope manufacturers, with Leupold & Stevens, Inc. (Beaverton, OR) being the most prominent. In addition, Premier Reticles (Winchester, VA) offers aftermarket mil-dot reticles that are based on U.S. Army or U.S. Marine Corps configurations. Custom mil-dots are available in multiple dot configurations, spaced in 100 yard or 100 meter increments that are tailored to a pre-determined cartridge load. Finally, luminous mil-dot I posts are also available from Premier Reticles.
The name mil-dot originates from the term "milliradian" and is based upon the spacing of dots of known size in mil increments on the reticle's crosshairs. Using the mil-dot formula, a range table can be formulated where the known size of the object is compared to the number of mils subtended. From this, the horizontal range-to-target can be determined in either yards or meters. Thus the shooter can either use a printed table derived from the mil-dot formula (usually included with scopes equipped with mil-dot reticles), or he can use the mil-formula directly.
Many snipers who have had extensive experience with the mil-dot reticle have found mental shortcuts based on the mil-dot formula or have used an abbreviated range table rather than using a complete table. A disadvantage to this routine may arise when a sniper finds himself in a stressful situation. Here, accurate calculations depend upon the sniper's ability to remember and then to execute the formula correctly. Assuming the horizontal range-to-target has been determined, the sniper still must compensate for a projectile drop or wind drift by a turret adjustment or a mil hold-over.
The Mildot Master™ is a 6.5 x 3.25 inch rectangle and is based upon an insert sliding between an outer vinyl envelope that is held together by rivets. The insert displays range in yards on one side and meters on the other side. Target Size and Bullet Drop scales on both sides of the slide are expressed in inches and feet. While the Mil-Dot Ranging Computer is a device that primarily calculates the horizontal range-to-target, the Mildot Master™ calculates this as well; but in addition, it calculates the correction necessary for an uphill or downhill target, and the corrections required for projectile drop or wind drift.
The front side of the Mildot Master™ has two sliding scales (Figure 2). The first reveals horizontal range-to-target based on target size and the corresponding mils that the target subtends. In addition, the scale has a series of indices that automatically correct for uphill and downhill shots. The second scale provides for corrections (scope adjustment or holdover) needed due to projectile drop or wind drift. Once the first scale has determined the horizontal range-to-target, the projectile drop or wind drift is automatically aligned with the corresponding MOA or mil correction.
The reverse side of the Mildot Master™ is designed to accept a ballistic data strip that contains drop and windage data for a specific cartridge with a specific loading. From these data, the shooter can utilize the projectile drop or wind drift scale to find the amount of correction necessary for the drop (drift) at the determined range.
Alternatively, if the "come-ups" for the rifle and load being used are known, these data can be taken directly from the data strip, resulting in an immediate scope adjustment for the determined range. The Mildot Master™ can also serve as a clinometer to determine the angle of incline or decline. This is accomplished by inserting a nylon string through a rivet located in one of the corners of the calculator and with a lead-fishing sinker to the other end of the string. The target is then sighted along the upper edge of the rear side of the calculator with the weighted string being allowed to steady itself. The string is next held in place and the unknown angle of incline or decline is read from the scale on the outer viny1 envelope.
The Mildot Master™ is beginning to catch on not only in this country but in other countries as well. Even though not on display at the recent SHOT Show, several individuals demonstrated this analog calculator and those who saw it were impressed. Placing a call to the owner of Mildot Enterprises, Bruce N. Robinson, before finishing this manuscript, I learned that his analog calculator is currently being reviewed by several branches of our armed forces, including the U.S. SEALS. It seems reasonable to predict that the Mildot Master™ will soon become an integral part of a sniper's