Exclusive: Understanding (& Improving) AR Triggers

By Glen Zediker

First, little can be done to improve a stock trigger. Any real help comes from the aftermarket. The last stock trigger I measured was a little more than 11 pounds. If trigger break weight is greater than rifle weight, well, it’s a little hard to shoot with.

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Mastering the trigger of your AR can make the difference between hits and misses when it counts.

Competitive position target shooters, like NRA High Power competitors, almost always prefer a two-stage trigger. It has free movement to the rear (the first stage), comes to a stop (at the second stage) and then breaks cleanly from that point as pressure is applied. A single-stage has no free movement toward the rear before the break, or isn’t supposed to. Competitive shooters prefer a two-stage because it’s more controllable and predictable. We use the first stage as the start to a shot, and also as a safety valve, of sorts, if we have to back out. Second, it’s a way to get a light break-weight (the second stage) while maintaining a higher overall weight (the first and second stage added together).

If you install your own trigger, make triple-sure disconnector function is 100 percent.

Getting the finger onto, and then into the trigger, simply makes for a more competent standing position shooter. First stage, plus second stage, equals total trigger-pull weight. That matters much to NRA and CMP Service Rifle shooters who can’t use a trigger less than 4-1/2 pounds. The triggers on my Service Rifles are two-stage, and the second stage is about 8 ounces at, as said, an overall weight of 4.5 pounds. The light second stage, therefore, means the trigger is not a handicap compared to an NRA Match Rifle, which has no minimum pull weight requirement. It does, however, require a little getting used to….

Another popular means to get a better performing trigger is dropping in one of the “modular” systems. In these, all the angles and adjustments have been made (usually) and the “box” pins in place of the standard trigger.

The original two-stage was the MKII as done up by Charlie Milazzo. Its workmanship and quality, not to mention, of course, its two-stage engineering, was a major milestone in fleshing out the AR-15 as a competition arm. Charlie owns the patent and it’s been a legal embroilment for quite a while now. Right. Most two-stage triggers are Milazzo clones. Others, however, took steps beyond Charlie’s original take, or at least took them in different directions.

Take a look at the hammer; it’s radically lighter than standard. Here’s a Geissele. It’s very well made, adjustable and way on fast to impact. Geissele has different “tunes” available to suit different needs.

What’s the best two-stage? Right now, for me it’s the Geissele (say “gih-sell-ee”). In terms of adjustability and design, it be “da bomb dot-com.” Jewell makes a good two-stage. It has a unique and easy adjustment system and spring arrangement (most others use essentially standard form springs) and installs easily. Lock-time is the main difference between these two, in performance.

Here’s a trigger assembled into a Brownells trigger fitting jig. This lets you install the trigger on the outside of your receiver so you can see every little nook and cranny, and how the metal-to-metal fits are working.

Lock-Time

This is defined, so I say, as the time between hammer release by the trigger and firing pin strike on the primer. The quicker the better. Everyone’s rifle is moving when it’s fired. Even the best prone position will exhibit some discernible movement, and no one’s standing position hold keeps the sights still for long. The sooner the bullet leaves, the closer to call the shot will be, which means bullet exit and perceived sight location will more closely coincide. Standing position shooting, of course, is where effects show most. This is most noticeable on a windy day.

Not everyone needs or wants a two-stage and there are outstanding single-stage systems. Single-stage triggers have the advantage of a shorter distance to reset than two-stage triggers.

The AR-15 is, by design, way, way slower to ignition than a bolt rifle. The AR-15 has a hammer, for one. Anything with a hammer is slower than any other thing with an inline striker. Lock time on a standard AR-15 is around 16 milliseconds (that’s 0.016 seconds). Lock time on an out-of-the box Remington 700 or Winchester Model 70 is about 4. Bill Geissele took this to heart and his trigger installs out of its poly bag at about 8 ms. Wondrous. That is a big deal difference.

Hammer weight matters to this. The trick here is getting one lighter that will hold up. Just grinding metal away may not do it… Hammer spring power has another decided influence. The heavier the spring, the faster the push. The caveat there is the heavier springs place the hammer under more tension, which can influence wear mightily. The combination of a lighter hammer and a stronger spring (unless both have been engineered to work together, as they have in a Geissele or JP Ent. for instances) add up to better performance, but for how long?

Pins & Springs

My experience has been better pins make for noticeably better trigger behavior. The better aftermarket triggers will have their own “matched” pins, which will also be precision-made (size and straightness). I highly recommend KNS-brand pins. They are well made and available in different sizes to suit.

Unless specified differently, pins install from right to left, ungrooved end first (there are exceptions). The reason is how the grooves engage the “J” spring in the hammer.

Springs matter. The idea is (usually) to get a lighter trigger return spring and a more powerful hammer spring. That can actually reverse, or at least the trigger spring part, if we’re shooting NRA Service Rifle because we want a higher first-stage weight.

On a stock-form trigger, aftermarket springs are about the only way to make its action better. On a competition-style trigger, knowing how to specify and manipulate springs can make a big difference in the “tuning” of something like a two-stage, such as doubling the trigger return springs to increase first-stage weight.

Installing a trigger isn’t at all difficult, but having it install to 1. Be what you expect performance-wise and, 2. Be what you need safety-wise, ranges from easy to very tedious. Depends, I am convinced, on the precision used in the manufacture of the lower receiver. Engagements and geometries of quality aftermarket triggers are engineered around (and in some cases actually installed into and adjusted for) a perfect blueprint lower. That essentially means the holes are oriented and located exactly as they should be.

The preceding is a specially adapted excerpt from The Competitive AR15: Builders Guide, a book by Glen Zediker and Zediker Publishing, (662) 473-6107, www.zediker.com.

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