To become a Sharpshooter, a candidate was required to fire a qualification course using a rifle brought to the competition by the volunteer. The course of fire consisted of shooting ten rounds as rapidly as the shooter could reload into a target ten inches in diameter at a distance of two hundred yards. All ten rounds had to hit the target and the average distance could be no more than five inches from the center of the target. This was measured using a fifty inch string. The end of the string was placed on the center of the target then run to the nearest hole in the target. The point where the string intersected the hole was then moved to the center and the distance to the next hole measured, then so on. If the end of the string was reached before the last hole could be measured, the volunteer was disqualified. Thus the term "A string of fifty" was born.

The Berdan Sharpshooters used a Sharps .52 caliber, breech loading rifle manufactured by the Christian Sharps Co. The rifle used a one piece cartridge consisting of a "ball" which was either glued or tied to a cylindrical cartridge of paper or linen which contained powder. The first Sharps cartridges were tied at the tail end. The block at the breech (back) of the firing chamber slid downward by the operation of a lever under the receiver and was designed such that, when closed, it would clip off the tail of the cartridge, exposing the powder. The primer cone was mounted on the top of the block. When the hammer fell on the cap, a fulminated mercury charge was ignited. Fire was routed through a vent in the block and into the chamber of the rifle, igniting the cartridge. Exposing the powder caused a problem of the grains of powder getting between the block and receiver. The cartridges were soon shortened and a primer of fulminated mercury was placed at the tail end of the round.

The Berdan uniform was of standard U.S. Army Wool. However, it was a distinctive green in color. "to blend in with the foliage and trees during the leafy season." They wore a green forage cap with a black ostrich feather. The jacket was a Frock Coat. The brogan shoes were covered with brown leather gaiters which rose to the knee to protect the legs when walking through brush. The buttons of the uniform were made of hard, black rubber to prevent the reflection of light. The leathers were a simple waist belt with cartridge box, cap box and bayonette. The Berdans used a unique Knapsack. The pack was of Prussian design, made of a wood frame covered with cowhide with the hair side out. A square mess kit was tied to the outside of the pack by use of leather straps.

Marksmen from the 1st and 2nd US Sharpshooters were the deadliest in the war. Berdan Sharpshooters were credited for a higher percentage of kills than any other unit in the war. Berdan Sharpshooters also suffered the highest casualties. This was due to their employment exclusively as light infantry. The Sharpshooters were responsible for patrolling in front of the main body of infantry. They would seek out the enemy, then engage them for the purpose of discovering the Rebel deployment. Once the Confederate bodies were located, The Berdans would report back to the commanders what they had found and establish battle lines for the main forces. Upon being relieved from the advanced assignment, they would reenforce the infantry, frequently supporting flanks to prevent the enemy from flanking a battle line, or providing additional support at weaker placements in the main line of battle. When it became necessary for the main body to retreat, the Sharpshooters would stay behind to prevent the retreating forces from being overrun.

The Sharpshooters trained exclusively in Skirmish Drill. Rather than fighting in one large massed body, the Berdans would deploy at intervals of five yards and fire in partners. Thus a canon blast would only disable two or three of the men on the line and two men next to each other would never have empty rifles at the same time.

The combination of skirmish line fighting, the rapid loading and the accuracy of the Sharps rifle proved deadly to many a confederate officer or cannoneer. A quick sharpshooter could fire as many as 6-8 rounds per minute with great accuracy and range in combat, compared to 2-3 for an infantryman using a muzzle loader. The Berdans were credited with kills at distances up to 800 yards and shots of 400-500 yards were not uncommon."