A question often asked is what the differences are between a single-stage and a two-stage trigger. This is fully understandable, as there are an astounding number of options available in the market today. Here we will discuss the differences between the two styles.
A single-stage trigger is a trigger where a constant pull to the rear will release the sear. The pull weight may vary depending on the firearm and the trigger itself. Some trigger pull weights can be measured in poundage in the lower teens, while others will have a pull weight in just a few ounces. The consistent feature, however, is that it is the same weight throughout the trigger pull until the sear releases.
A two-stage trigger is just that, with two separate stages that can be felt in the pull of the trigger. The first stage will pull back somewhat like a single-stage trigger. However, at the end of the pull, it will hit what most describe as a “wall.” This wall is the heaviest part of the pull, and the start of the second stage. The second stage is usually, but not always, a lighter pull than the first stage, and generally shorter in pull distance as well. However, the wall is significant in that it signals to the end user that the trigger is close to being fully pressed. For instance, the Geissele SSA trigger, one of the most popular 2-stage triggers on the market, has specifications listed as a 2.5-3.0 lb. first stage, a 1.5-1.75 lb. second stage for a total of 4.25-4.75 lb. of pull. Just as a single-stage, two-stage trigger can vary dramatically in weight of pull, and in both stages.
The final decision of which trigger should be used can vary significantly depending on several factors. The largest is simply individual choice, as many people simply prefer one style over the other. The single-stage is commonly regarded as a slightly faster trigger to use, and usually available in lighter weights than the two-stage. The two-stage tends to be used in scenarios where target designation is needed, or in higher adrenaline situations. If possible, it would be recommended to try both styles, and see if one feels more comfortable to use.