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8/19/2014 4:57:02 PM
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jetspeedz
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Posted: 2/2/2013 6:40:25 PM
[Last Edit: 2/2/2013 10:20:22 PM by jetspeedz]
I decided to build another custom rifle, like the rest of the critical components on this AR, I had to choose a trigger. I had previously tested various match triggers and performed trigger jobs on factory triggers for various platforms, in the end I decided to go with the 3.5lb drop in CMC Tactical straight trigger for this build which I can compare to my drop in Timney 3lb skeleton trigger. Similar to the rest of the components in this build, I wanted to buy parts which were made in the U.S. CMC is no exception, being 100% produced in Texas.

I often get asked what the best trigger is for my AR, and I typically respond there is no best because it is all subjective. When it comes to triggers, in my opinion there are either good or terrible triggers. Poor quality triggers are easy to pick out and most people would agree, however when it comes to a quality trigger it varies person to person. There are a variety of two stage and single triggers available on the market and each have their purpose. I prefer single stage triggers and all to be around 3lb, so I picked this CMC trigger because I like the design and marketing material looked promising. Like all triggers, you can’t judge them until you actually have them in your hand and begin testing.

CMC is truly a family run operation with Co-Owner/General Manager David Biegel in charge. I spoke to David and Jack Biegel V.P. & co-owner on the phone and the biggest problem they had was keeping the triggers on the shelf due to the high demand. CMC Triggers is affiliated with Chip McCormick who is well known in the 1911 community, they are a separate entity which deals specifically with match grade triggers for the AR platform.

My initial impression of the trigger was positive from the sturdy 410 stainless steel metal housing to the finish on the sear and hammer. The flat trigger bow was comfortable and has an edge in design which suited my custom build. Unlike my Timney trigger, the edges of the bow are rounded and comfortable. It came packaged with instructions, pair of oversized small .154" hammer and trigger pins and c-clips. I installed this trigger in my Mega Arms billet GTR-3H lower, which is a high precision CNC cut lower. As I have stated in other reviews the tolerances of Mil-Spec parts vary from manufacturer to manufacturer so the fit will vary depending on your lower. CNC parts are usually more precise than forged counterparts due to the tight tolerances of the machining process. No special tools are required, so anyone should be able to install this trigger with ease, however an e-clip tool will help getting the c-clips installed easier. Installation required removal of the grip and safety selector. The fit of the trigger was spot on and slid in like a glove. I was a little worried about the pins and the c-clips potentially scratching the surface of the lower but the clips are very small and one side is polished smooth compared to the other to prevent any wear which was a pleasant surprise. The oversized pins required a little bit of lube and force to slide into my lower which is not a problem as it provided a tight secure fit when sliding through the trigger group. CMC provides spare c-clips in case you lose them, installing the c-clips took a little bit of patience and creativity without e-clip tool, but once everything was complete I dry fired the trigger and it performed as expected.

When it comes to comparing match grade quality triggers like CMC to factory FCG, it all depends on the factory trigger tolerances, some are far worse than others when it comes to take-up/pre-travel/slop, travel/creep, break weight, over-travel and trigger reset. Since CMC is marketed as a tactical trigger, not a target trigger, the characteristics should be more in line with a factory trigger, but it was not. Most factory triggers have a small amount of take-up which is perfectly normal. My Stag FCG has quite a bit of take-up but CMC had no measurable take up at all. Take-up/pre-travel/slop is the movement of the trigger before it contacts the sear. Another way to explain this is the movement of the trigger from rest before you feel any significant resistance and before sear movement. Pre-travel on the CMC is on par with a target trigger like my Timney, which has no pre-travel. I did however notice you can actually pull the trigger forward, towards the muzzle about 1/8" when the safety selector is in the safe position. This does not affect the functionality in the safe or fire position. In the fire position the trigger operates normal with no pre-travel and the spring pressure does not force the trigger move forward beyond the normal reset. I suspect this 1/8” movement is partly due to the design of the safety selector in combination with the CMC trigger safety pad. I did not see this kind of movement on the Timney trigger when in the safe position for what it’s worth. The next step of the trigger stroke is what is often called travel/creep. When the sear moves off the hammer notch as you pull the trigger on some triggers you can actually feel the movement. The grittiness/drag people refer to during the travel, is due to poor finish on the surface of the hammer or sear and/or poor tolerances. The angle of the hammer hook is critical for a perfect clean “glass/crisp” break. Gunsmiths can change the angles and polish the surfaces along with changing the spring to get the “perfect” trigger as a part of a trigger job package. I have performed trigger jobs and I can’t stress enough how important it is to avoid taking too much material off as these parts are measured in thousandths of an inch, a quality trigger will have enough travel to keep the trigger safe while reducing the ill effects of trigger creep. This trigger had no measurable travel and no creep in my opinion. It has a nice clean “crips” break without any gritty or rough feel which is what you expect out of a match quality trigger. Compared to my Timney, it is difficult to notice the difference for the average person, but there is ever so slightly more travel on the CMC. The break weight is basically the force required to move to engage the trigger and what companies advertise for trigger weight. I measured the trigger and consistently read ~3.42lb of break weight, this is right on par with the advertised 3.5lb. Keep in mind this is a brand new trigger and the springs are new, I suspect overtime the break weight will slightly change with wear. Over-travel is the distance the trigger moves back after the travel stage, when the gun fires. Most Military tailored triggers have quite a bit of over-travel for reliability since they encounter various environmental conditions. The extra over-travel prevents malfunctions, but the downside is trigger rest, and for some, disturbing the sight picture on follow up shots. The trigger job I performed on my home defense pistol has very little over-travel, it is always maintained and clean enough so you can eat food off of it, so I’m not worried about debris preventing the gun from firing. CMC has designed this trigger to work in various conditions to not only meet but surpass Mil-Spec standards, there is measurable over-travel on this trigger for reliability. When it comes to over-travel affecting the sight picture, it is really a matter of opinion, a well trained shooter would not be affected by over-travel, however some prefer very little over travel. The Timney trigger has less over-travel, but it is also tailored more towards target shooters. Lastly trigger reset which depends on the over-travel is the stage where you move the trigger forward before the disconnector resets. Some triggers like my Glock are very tactile and even auditory where you can feel and hear a click once it resets. Hammer and sear angle geometry also impact trigger reset, CMC’s geometry follows Mil-Spec, it does not need any modification like the rest of the trigger. CMC has a very short reset which is great compared to a factory FCG, but not as short as the Timney. When it comes to reset, it is a matter of preference, but what is more important than the actual distance is consistent tactile resets. CMC can not only be heard but you can feel the reset. It is also worthwhile mentioning CMC uses high quality springs in their trigger and while you cannot easily adjust them without taking the trigger apart which will void the warranty the return spring force is tuned perfectly and does not need to be altered.

Field testing CMC trigger using various ammo yielded positive results with about 3% of .22LR rounds which failed to fire due to poor quality ammo and not light strikes. Since bricks are cheap and not the best quality ammo you can expect a few to FTF. On the higher quality match ammo, there were no FTF and overall I’m very pleased with the CMC Tactical trigger. CMC offers a 30 day no questions asked return policy, but even better they test their new trigger designs and put them through the ringer with series of live and lab tests performed by an independent Engineering firm to validate the design and durability of the trigger. When a company puts that kind of effort and time behind a product they are putting their name on it shows they care. I would not hesitate to recommend this drop in trigger to anyone looking for a great match quality tactical trigger.

Install Video
http://www.youtube.com/watch?v=f24YeYXZeYU