Throwback Thursday: AR-15 Two-Stage Triggers

By Glen Zediker published on in Gun Gear

In my estimation, a two-stage trigger in any rifle offers the most secure, precise, and safest function. Two-stage triggers appeared in U.S.-issue service rifles, such as the 1903, M1, M14. But for the AR-15/M16, it took the civilian-side aftermarket to create the two-stage trigger. The main reason other military-use rifles carried two-stage triggers is, primarily, because they are safer. There are other attributes to discuss, but safety is the main point in favor of a two-stage.

There are a good many two-stage triggers available now for the AR-style rifle platform. Development of available adaptations has been ongoing after introduction of the original and patented design by Charlie Milazzo. Most are knock-offs of his MKII; some are as good, some may be better, but the majority, in my opinion, are also-rans. A lot of fine work goes into producing a truly good trigger.

Being able to ride the trigger face, taking up the first stage, riding it back out when needed, makes for radically better performance in less stable firing positions. I use the first-stage take-up as a sort of “switch” to engage myself with the upcoming shot. If it’s not right or I’m running out of air, back off, regroup, and then go again. This off and on tactic requires a lot more finesse if you’re using a single-stage. And, since engagement doesn’t change with the two-stage, neither does the trigger feel. Sometimes a little off and on can nudge a single-stage into a lighter break. Photo by Glen Zediker © 2015.

In competitive shooting, being able to ride the trigger face, taking up the first stage, then riding it back out when needed, makes for better performance in less-stable firing positions. On High Power competition targets, the author uses the first-stage take-up as a switch to engage the upcoming shot. If it’s not right or he’s running out of air, he backs off, regroups, and then goes again. This technique requires a lot more finesse if you’re using a single-stage trigger, he believes. And because engagement doesn’t change with the two-stage, neither does the trigger feel. Photo by Glen Zediker © 2015.

I’m often in the company of a gamut of AR-15 users, and the leading initial reactions from someone who first fires one of my competition guns results from the trigger function. “Whoa, how do you have so much creep in the trigger?” Fair question, because that’s what a two-stage trigger feels like. But from a functional standpoint, it’s not creep.

The two-stage trigger design features a tensioned first-stage movement or “take-up” prior to engaging the sear lever. The take-up of the first stage begins to minimize the amount of sear engagement, until it “bumps” into the second stage. This bump stops rearward trigger motion, indicating that the sears are then at minimum engagement. Depending on how the trigger has been adjusted, it may take only a few more ounces of rearward trigger pressure to cleanly overcome the second-stage weight and fire the shot. Because the sears are not minimized until the first stage is taken up makes a two-stage a safer trigger. Two-stage trigger sears have a large amount of sear overlapping until the first stage has been completely activated, that is, pulled through.

First stage added to the second stage is the total pull weight. So, it’s possible to take a majority of this total weight out of the pull in an effectively unnoticeable manner. A two-stage trigger is a better platform for breaking an accurate shot because it is easier for the shooter to feel the remaining additional weight (the second stage) as opposed to overcoming the total pull weight for a single-stage trigger. On my competition rifles, which have the very best two-stage triggers installed (and a whole lot of tuning time expended), I set the second stage to a relatively light weight.

Again, the safety point: If we have a second-stage break weight of 1 pound, after overcoming, say, 3 pounds of first-stage takeup, that is a far safer trigger than the 1-pound break weight single-stage necessary to duplicate the effective break weight of the “4-pound” two-stage. Follow?

Unlike a single-stage (which simply releases after so much pressure is applied, with no prior movement), the shooter can put his finger on the two-stage trigger face, prepare for his shot, and then reconsider it. Back it out, and start it over. With a single stage, when the finger goes on the trigger, the next thing that happens is the shot, or the finger comes away from the trigger face entirely to stop the process. There’s much more “connection” controlling a two-stage let-off.

Here’s the original, the MKII by Charlie Milazzo. A long-time competition M1A builder, Charlie figured out how to do the two-stage for the AR-platform. Look closely at the illustrations and see how sear engagement changes from first stage to second stage. There’s a whopping lot of sear engagement prior to initiating the pull though the first stage, and a very “crisp” break from minimum engagement waiting after the bump when the first stage has ended. In a single-stage, such minimal engagement is necessary to get a crispy break, but it’s not as safe because it’s minimal from the get-go. In a true two-stage, releasing back through the first stage take-up also returns sear engagement to where it was. Another minor point, with major influence, is that since sear engagement returns to its formerly generous self after a shot, there’s not going to be any “tripping” of the sear as there can be with a single-stage that’s adjusted to a light weight. This can happen from the shock of bolt carrier assembly inertia. For this reason, it’s possible to attain a lower actual break weight with a two-stage. Photo by Glen Zediker © 2015.

Here’s the original MKII two-stage trigger by Charlie Milazzo, a long-time competition M1A builder. Look closely at the illustrations and see how the sear engagement changes from first stage to second stage. There’s a lot of sear engagement prior to initiating the pull through the first stage, and minimum engagement when the first stage has ended. In a single-stage trigger, such minimal engagement is necessary to get a crispy break, but it’s not as safe because it’s minimal from the get-go. In a true two-stage, working the first stage take-up also returns sear engagement to where it was. Another minor point is there’s not going to be any “tripping” of the sear as there can be with a single-stage that’s adjusted to a light weight. Photo by Glen Zediker © 2015.

Better is better. The question is always how good do you want? The “drop-in” and non-adjustable two-stage triggers out there are better than almost all stock triggers, immeasurably better, in my estimation. That said, tuning two-stage triggers requires a little creativity, but the better two-stage (and single-stage) “match” triggers have provisions for second-stage engagement adjustment. First-stage takeup weight can be adjusted with altering or replacing trigger return springs.

What’s less than ideal about two-stage triggers? Foremost is cost. But that’s something each shooter can decide to absorb, or not.

Second, I’m not convinced they are all reliable. I’ve not had one of mine malfunction, but I have had them change and require tune-up. The only trigger malfunctions I’ve encountered have been in tricked-up single-stage units. Keep a two-stage model well lubricated and clean, and it will deliver consistent let-off results, in my experience.

Another factor to note is that the distance to reset is greater with every two-stage I’ve encountered. By that I mean, how far the trigger must move forward after firing to reset the hammer for the next shot. If someone is trying to shoot rapid-fire as quickly as possible, a two-stage will slow things down. That was one of the first things I noticed when I first fired an AR-15 two-stage trigger. Compared to my previous competition NRA Service Rifle, the M1A, it felt like an eternity before I could get settled in for my next shot. The trigger in the M1A can be tuned so there is only a miniscule lessening of pressure on the trigger face necessary to reset, so it’s possible to shooter faster when the conditions and course warrant it.

Still, after you get accustomed to one in your AR-style rifle, a two-stage is the only way to go, in my opinion. A two-stage not only allows for more precision in firing, but it’s safer to use.

Do you own any two-stage triggers? What do you like, or not like, about them? Tell us in the comments below:

 

Glen Zediker is the owner of Zediker Publishing, which has published detailed books on firearms for 25 years. Titles include The Competitive AR15: Builders Guide; The Competitive AR15: The Ultimate Technical Guide, The Competitive AR15: The Mouse That Roared, Handloading For Competition, The Rifleman’s Guide To Rimfire Ammunition, Service Rifle Slings, and Slings & Things. He has worked professionally with some of the greatest shooters on the planet, as well as leading industry “insider” rifle builders, manufacturers, and proven authorities on gunsmithing, barrelmaking, parts design and manufacture, and handloading. And he does pretty well on the line: Glen is a card-carrying NRA High Master, and he earned that classification in NRA High Power Rifle using an AR-15 Service Rifle. Correspond with him here.

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Comments (17)

  • Kirk B Mullins

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    I have had several discussions with friends and read several articles on single vs. 2 stage triggers. My estimation is that people tend to prefer what they originally learned on, or what they are comfortable with. Both types have there advantages & disadvantages. I personally prefer the 2 stage trigger because I know precisely when the hammer is going to be released to fire a round down range. It is a logical assumption that this will lead to higher accuracy, consistency & safety. That does not mean that a shooter can not be just as good. or better, with a single stage trigger. it is all about the time spent with the firearm. Knowing your firearm’s characteristics is one of the key essentials to accuracy & efficiency with it. Firing it consistently & correctly helps to improve a shooters accuracy. So know your firearm well, especially if your life, or the lives of others, are depending on it on a regular basis. It could be the one thing that puts you at an advantage when it counts.

    Reply

  • mach37

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    Seems like the first diagram is missing from this article – how the action looks before the trigger is pulled. The pic labeled “Hammer reset after cycle” would seem to be the logical “first” diagram, showing the assembly before the trigger has been pulled.

    Reply

  • mach37

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    “Better is better” is not a real argument, in my opinion. I can’t fault my Timney 667S single stage; it corrected the complaint I had with my stock Eagle-15 trigger.

    Reply

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