Mildot

Tech Notes

Ballistic Mil-Dot™ Reticle

200 yards 300 yards

-1.6” -7.3”

.80” Corr@100 yds 2.43” Corr@100 yds 4.58” Corr@100 yds 7.20” Corr@100 yds

History In 1998, it became clear to Burris that sportsmen’s interests in long range shooting had grown considerably. The advent of laser rangefinders, more long range rifle designs, more magnum cartridges, and super accurate ammunition,long range shooting became more popular and achievable. However, a vital link in long range success is a trajectory compensating scope reticle. In 1999, Burris introduced the Ballistic Mil-Dot reticle in a 6X-24X Signature Series scope, primarily with the varmint hunter in mind. While under development, Burris recognized that the ballistics of the popular .22-250 55gr varmint load was very similarto that of many flat shooting big game cartridges out to 500 yards or more. Demand for this type of reticle was also strong from big game hunters, and Burris soon expanded the Ballistic Mil-Dot offering to include the 4X-16X and 8X-32X scopes. This reference piece is designed to be used in conjunction with the Ballistic Mil-Dot reticle guide which is included in the packaging with each scope. Aguide to using Mil-Dots for range estimation and wind drift compensation is also included in the packaging with each scope and therefore is not covered in this technical discussion.

400 yards -18.3” 500 yards -36.0”

600 yards -62.6” 10.43” Corr@100 yds

700 yards -101.3” 14.47” Corr@100 yds

Ballistic Mil-Dot Design Considerations The Ballistic Mil-Dot reticle begins as a standard Mil-Dotwith two exceptions. The first is that all the mil-dots are round instead of oblong. Shooter feedback suggested that round dots are easier to distinguish than oblong dots. Second, is the conversion of the mil-dots on on lower vertical crosshair to Ballistic lines. Hundreds of iterations were considered, and the final determination perfectly matches the ballistics curve of a .22-250 55gr Sierraboattail load at a muzzle velocity of 3680fps, fired at 3,000 feet altitude, 59 degrees and barometric pressure of 29.53. Because the comparative need for accuracy is greatest while shooting prairie dog size targets (compared to big game), an average altitude and environmental conditions parameter was utilized for this type of shooting. The Sierra Infinity™ Ballistics software program was utilizedfor all calculations and verified by field shooting. Although a miniscule amount of shooting occurs beyond 500 yards, Burris elected to provide a total of 7 sighting references for maximum flexibility and for the purpose of minimal sight picture departure from the standard mil-dot. Per the spirit of the original design, this would allow accurate shooting out to 700 yards. Some would contend (andBurris would agree) that these cartridges are so flat shooting out to 200 yards, that a separate 200 yard reference is unnecessary. However, significant consideration was given to making the use of the reticle intuitive and not subject to the failings of memory for occasional shooters. As designed, counting the ballistic lines is easier starting at 100 yards as the center reference, rather than“remembering” to start counting at 200 and discounting 100 yards. For those who subscribe to the 200 yard zero, a bit of work with the Sierra Infinity Ballistics software program (or other similar ballistics programs) will still allow the shooter to calibrate and optimize the reticle to his particular cartridge, environmental parameters, and shooting style. Factory Calibration Burris Ballistic Mil-Dotscopes are of the American-standard non-magnifying reticle design. As you change the magnification, the reticle remains constant in size as the image changes in size. Therefore, the reticle’s size in relation to the image size (reticle subtension) changes so the amount of trajectory compensation changes as magnification changes. This necessitates that the scope be set at a specific magnification...