I have been promising a follow-up on the AR-15 triggers discussion. Well, here it is.

    Since I last broached this subject, I would say I have learned quite a bit. In fact, I have become very comfortable with the workings of the AR-15 trigger and feel that I am capable of doing excellent trigger jobs on my own rifles. I do now understand why trigger jobs are relatively pricey for the AR-15. While the operation is not difficult, it is very time consuming, and the time invested is directly proportional to how picky one is about trigger performance.

I am very picky, so I plan on spending about 4 hours per job.

    I really don’t think that this number can be substantially decreased by any factor other than luck. There is the off chance that your receiver pin locations are in the exact location as the trigger design criteria demands. Chances are that this is not so. A few thousandths or even a single thousandth could make the difference between a perfect trigger and a so-so trigger.

Remember this fact as I elaborate…

AR-15 trigger parts in simple terms:

bulletTrigger-  this is the part of the trigger assembly that your finger touches. This has its own spring that adds tension to the trigger. The primary sear is located on the trigger, typically in the front of the trigger. In the case of the Armalite and Milazzo, the primary sear is in the rear.
bulletTrigger spring- the only function of the trigger spring is to return the trigger to the home position after the trigger is pulled to the rear. This spring also contributes to the pull weight of the trigger. (In a simulated two-stage like the Kreiger-Milazzo, Compass Lake and Armalite, the first stage pull weight is almost exclusively affected by the trigger spring).
bulletHammer- the hammer is the mechanism that strikes the firing pin. In an AR-15 the hammer is of the rotational variety, and swings from the rear in an arc of almost 90 degrees to strike the firing pin. This occurs after the hammer hook slips off the sear after the trigger is pulled to the rear.
bulletHammer spring- this is the beefy spring that affects the hammer to strike the firing pin. The hammer spring and hammer weight both affect lock time. The hammer spring tension is also a major contributing factor to trigger pull weight.
bulletDisconnector- The disconnector is a spring loaded hook that grabs the hammer as it moves to the rear and keeps the rifle from doubling. Will also be referred to as the "secondary sear system".
bulletDisconnector spring- The disconnector is spring loaded to allow the hammer hook, in the cocked position, to pass the front of the disconnector, while the trigger is pulled to the rear.
bulletSear- the "primary sear" typically found on the forward tip of the trigger. The sear is the knife edge that, once disengaged from the hammer hook, allows the hammer to be released. The primary sear is located on the trigger, typically in the front of the trigger. In the case of the Armalite and Milazzo, the primary sear is in the rear.
bulletTrigger pins- these are the two pins that pass through the lower receiver that retains the hammer and trigger.


    My direct experience, so far, only touches the Armalite NM, Kreiger-Milazzo, JP Enterprises, and the Compass Lake. All of these triggers are touted as two-stage triggers except for the JP, which is a single stage. Actually, all of the AR-15 two-stages I have seen are actually long pull single stages with a secondary trigger spring that acts through some outside mechanical means. This two-stage effect has been achieved through different means.

The Two-Stage

    The Armalite and the Kreiger-Milazzo are essentially the same geometry, and use a clever copy of the US military double hammer hook which is found in the Garand and M1A. The sear is moved from the front of the trigger, which is the standard AR-15 geometry, to the rear-top of the trigger. The disconnector is also moved to the back of the trigger. Basically, the primary sear starts in contact with the hammer hook and is only under the tension of the trigger spring until the back of the hammer contacts the front face of the disconnector (at the rear of the trigger), which, of course, is also spring loaded. At this point the pull weight becomes a summation of the trigger spring and the disconnector spring. The only real difference is that the Milazzo is adjustable without cutting.

    The Compass Lake system accomplishes the same two-stage effect in a different way. Basically, this system is based on the stock AR-15 trigger. It uses a modified trigger, hammer and safety assembly. In short, from my observations, the hammer hook has been modified to fix the over-camming effect of the hammer in the first stage in the mil-spec arrangement. The sear geometry has also been modified, I think. The real unique part is the new safety assembly.

    The CL safety has added overtravel and creep adjustments. The two-stage effect is the result of a spring loaded detent that acts on the back of the trigger. It is really the same concept as the rear hammer hook type two-stages, in that the second stage results from the summation of the primary trigger spring and the detent spring in the safety. The results are really quite smooth and predictable. The two-stage is also fully adjustable and is not very complex. Second stage weight and engagement are independently adjustable. The first stage weight, as usual, is a function of the primary hammer spring.

bulletThis can be a really good system for "DCM" rules, because the primary trigger spring can really be loaded up by bending the feet down creating more tension. Most of the pull weight can be moved to the first stage when a minimum pull weight is required by the rules.
bulletThis system is also bad, in my opinion, because the second stage has to have creep. It is inherent in the design! If creep were to be adjusted out of the second stage, the second stage would disappear! True, in a really good trigger job, this is minimized, but I don’t see how it can last because the tolerance is so tight! Usually what happens is that some creep is built in to be on the safe side.
bulletA two-stage design has a lot of moving parts, all of which wear. Armalite has tried to convince everyone that they can get away with not having adjustments on their trigger, don’t you believe it!

Just for the record:

bulletI do not like the Armalite. I will never, ever pay for a match trigger that is not adjustable without cutting. The instructions that Armalite provides for "adjusting" the creep out of the second stage (which is impossible) says that you stone on the hammer hook. Well, the hammer hook is $75 and few thousands too far, well…
bulletThe Milazzo is sweet, but no better that the Compass Lake.
bulletI have few comments about the way the size of the adjustment screws on the Compass Lake, but other than that, I think the Frank White system is the best-buy in the two-stages, by far.
bulletCompass Lake triggers are immediately available. Bonus!
bulletThis whole idea the Milazzo has some kind of rights to their "design" is very suspect. The whole double hook system is well used. Adjustable triggers are also very common, I find it very hard to believe that the U.S. patent office would say the Milazzo’s adjustment screw was unique. (I am in the process of applying for a patent right now, for a piece of machinery I designed).
bulletI ordered a Jewel two-stage in November of 1998, still no word. I Bet their product is exceptionally good, but who gives a shit! Don’t get me wrong, this is no fault of Jewel. It is not their fault their product has so much demand. I am sure they would love to sell me a trigger, me and about a million other guys.

The Single Stage

     The king of the AR-15 single stage is JP Enterprises. Others do exist, like the Derrick Martin, which is supposed to be quite good, but the JP can be purchased just about anywhere. The JP is also very common as an OEM match-trigger system, and can be had from just about any AR-15 manufacturer (Note: the JP 4 ½ lbs. trigger in the Ghogkiller’s DPMS "DCM" rifle is as sweet as mine, and I spent four hard hours and two disconnectors on mine). I got one of mine from Midway for goodness sake! The other one I did for my match gun was purchased directly from JP, which I highly recommend. One phone call and I had my fire control system in two days.

The JP can be had in degrees. One could purchase the trigger only for $99 and use the stock hammer, pins and springs. This is what I have on my service rifle and I think this is all you need for the 4 ½ pound setup. Mine has been rock solid. For a match rifle I recommend the fire control system kit for $169 direct from JP. This includes the trigger, match springs, oversize moly receiver pins, and the speedlock hammer. John at JP says he matches these parts when he makes a kit. My match rifle breaks like a bolt gun trigger at 2 ½ lbs. using very conservative settings. If you like, overtravel can be completely eliminated, I like just a tetch’ of overtravel. Creep is non-existent.

bulletThis system is drop dead reliable.  I have never had a double as a result of the trigger. (Little advice: if you blow some primers, look underneath the trigger very carefully. I mean very carefully!
bulletA crisp 4 ½ pounds does not feel like 4 ½ pounds.
bulletIf the trigger breaks exactly the same every time, your finger will get smart quick. I have noticed no advantage of moving a first stage through 3 ½ pounds over pre-loading a single stage 3 ½ pounds with my finger.
bulletLess moving parts, always good over the long haul.
bulletThe only cutting required for fitting this system is done to the OEM disconnector, which can be had at a gun show for $4. The fire control system comes with an extra. If you screw it up, no harm, no foul.
bulletThe back of the trigger must be cut to fit the safety, but this fit has no ultimate effect on the quality of break. Go slow and this is no problem. I recommend that the safety be kinda’ hard so that the trigger is held securely. The reset on the JP is very short.
bulletAdjustable from the top for sear engagement (creep) and overtravel. Pull weight is a function of the trigger and hammer springs.
bulletInstructions for installation are second to none and John can help over the phone.

   I think the single stage triggers have gotten a lot of bad talk because most of the Highpower shooters started on the .30 caliber’s. A lot of guys want their AR’s to feel like an M1A. I have heard gunsmiths say a lot of uninformed things about the new single stage triggers that are a leftover from the days of stock trigger jobs. Let me just say, the disconnector function on a JP trigger is just as good as the disconnector function on a Milazzo. When both are properly timed, a disconnector is a disconnector. I have seen no evidence that one trigger outlasts another, there are many good specimens to be had.

    I think that one thing to look for is adjustability. Just face the fact that bearing surfaces wear and will need to be adjusted eventually. I haven’t touched my JP’s since they went in both my rifles, but I do know that I could add a ¼ turn of sear engagement if I need to, and it would only take about two minutes to do.

I comment on my triggers:

    I was at Perry this year looking for my friend Junior who was shooting in leg match in the Nationals (never did find him). I had made a point to get to Perry during Highpower week so I could see all the cool AR-15 stuff in commercial row. I was in talking to my friend Carl who owns Champion Shooter’s Supply. I just happened to step into his shop when Mr. Zylanak of Zylanak Sights walked in to do some business with Carl. We started shooting the poop a bit and I asked him some questions about my Zylanak sight that was on my match rifle. I told him that it was out in the truck and he wanted to check it out. No sooner than I had the rifle out of the case, he asked if I wanted to buy a Jewel trigger. I told him that I was very happy with my JP. One pull of the trigger and he was in agreement that there was no reason to switch. The Jewel was no better!

I get the same response about my service rifle trigger, no one believes it is 4½ pounds! If this makes any sense, I think that the low duration of force required to break an extremely crisp trigger feels lighter than a lighter trigger with any hint of creep. Pay attention to quality of the break not the quantity.

   To conclude my little article, I will just say that the AR-15 trigger mechanism is somewhat limited in its current configuration. That is, in relation to a bolt gun trigger. The problem is that the pull weight of the trigger is heavily dependent on the tension in the hammer spring. The force present in the hammer directly acts on the sear. This same spring is also directly related to lock time. The most positive way to lessen the trigger pull weight can be had by lightening the hammer spring. The problem is you just created another problem related to lock time and primer strike. JP Enterprises does address this in their fire control system. The hammer spring they supply is much lighter than OEM, but so is the speedlock hammer! This is how they easily achieve a 3 lb. trigger. I do not know if lock time is reduced with the JP hammer, but I do know the trigger weight is reduced by a few pounds with substitution of the JP spring.