The new innovations in firearms during the time of the Civil War led to a drastic change in strategies where a full frontal assault was no longer a solid strategic plan. Both the Union and Confederate armies began the Civil War using single shot rifles. During the course of the war, however, rapid-fire/multi-shot guns were introduced to both sides for the first time in the history of war. At the same time, revolvers were introduced.
While the Smith & Wesson Model 1 was not a popular war item, the Model 2, a slightly larger caliber (.32 compared to .22) was introduced in 1861 two months before the firing on Fort Sumter/the start of the Civil War. This model was favored by several soldiers, who found it compact and reliable.The biggest impact of the Civil War on gun culture was that “after the Union’s huge advantage in industrial weapons production crushed the agrarian South, huge numbers of used and surplus weapons went home with both victor and vanquished. A generation of combat-hardened young men had learned the relatively new lesson that firepower prevails. Disastrous and abortive Reconstruction-era violence followed, and much of the “wildness” in the West can be attributed to these young men and their arsenal.” Also, there was a selling of surplus guns overseas, and the use of the more accurate and dangerous guns to keep Native Americans on reservations while also exterminating the buffalo. Often times, the Civil War is referred to as “the critical period in the formation of an American gun culture."
NOTE: for more information on the origins of gun culture in Amercia (as this is a much debated topic), you might try exploring some of the following works: Shooters: Myth and Reality of America's Gun Cultures by Abigal A. Kohn; "The Origins of Gun Culture in the United States" 1760-1865 by Michael A. Bellesiles and Arming America: the origins of a national gun culture by Michael A Bellesiles
 Hawley, Frederick. “Civil War and Small Arms.” In Guns in American Society: An Encyclopedia of History, Politics, Culture and the Law, edited by Gregg Lee Carter. 2003. http://www.credoreference.com/entry/abcguns/civil_war_and_small_arms