Single Stage vs Two Stage Triggers: AR15 Trigger Testing
BY PGF
1 year, 4 months ago
While the dispute between single stage vs two stage trigger is very much a preference thing, this won’t be a preference article. This article will discuss build and mechanics, the options and reliability of each, and why one might be chosen over the other in specific situations.
When thinking of a single-stage vs a two-stage trigger, the main terms that need to be known are hammer, sear, and disconnect. As these three parts will differ between triggers in an AR.
Hammer:The hammer is released when the trigger is fully pulled, striking the firing pin to ignite the primer of the round. Note: The hammer does have a portion on it that is known as the “searing portion” but it is not usually referred to as the main sear.
Sear: The sear is a separate part from the disconnect and hammer. The sear will be the last ledge that the hammer slides off of before being totally released to hit the firing pin. Dependent on the trigger, the sear can be a part of the trigger or its own separate piece that is then connected to the trigger.
Disconnect:The disconnect holds the hammer down after the trigger is pulled and the gun is cycling. As the gun is cycling, the hammer is pushed down and held down by the disconnect. This disconnect will then release once the gun has fully cycled and the trigger has been released. Once the disconnect releases the hammer, the hammer is now being held down by the sear.
Below is a graph provided by TriggerTech of various trigger pulls comparing pull weight and trigger travel distance. You can see the different forces and trigger travel required to set off different triggers as well as the amount of variation from trigger to trigger.
As some are better with words and some are better with actually seeing it, below is one of the better videos I’ve found in explaining the mechanics of the single-stage vs two-stage trigger. His example being with a Mil-spec single stage trigger in a standard AR-15 and then a Geissele Super Dynamic Two-Stage trigger.
It is worth it to note that all triggers will be different, even when it is a simple single stage trigger. Aftermarket triggers such as Triggertech, Hiperfire, and CMC are all very intricate designs and will differ from the example below but will have similar steps of operation.
Educational details about build and applications at the link.
On July 10, 2023 at 11:25 pm, RHT447 said:
The first two stage trigger I installed was a Milazzo-Kreiger into an H-Bar A2 I built for NRA Highpower back in the early 90’s. My current go to is Geissele. These two and others basically use an adaptation of the M1 Garand trigger. The similarities can be seen in this video–
https://www.youtube.com/shorts/D_JHj0BjUI0
No need to reinvent the wheel.
On July 12, 2023 at 10:35 am, Dirk said:
All my ar rifles are running single stage straight triggers. Anymore there are so many fantastic triggers on the market it would be difficult to not get a great trigger.
I’ve got a drawer full of mil spec triggers from over the years. Nothing wrong with them, I just prefer drop in straight triggers. Own multiple brand names.
My sniper rifles bolt guns are all being transitioned to Calvin Timney triggers, my god are they sweet!