Next up in the series of AR-15 drop-in triggers for review is the flat trigger unit from CMC Triggers. This trigger pack has represented the lowest-cost, drop-in option on the market for many years, only outseated recently as the budget leader by the Velocity Trigger. Let’s dive in and see how it stacks up on features and fundamentals . . .
MSRP comes in at $189.99, and it’s widely available online for about $167.
I’ve been describing the build of the trigger units to far — materials, finish, machining process, etc — but CMC is pretty vague on its website. The information available is:
- Tolerances of +/- .001″ for all engagement surfaces.
- Hammer, trigger, disconnector and pins are made with the highest grade, hardest, longest-wearing materials available.
- The assembly is contained in a high-grade 410 stainless steel housing.
- Full-strength rocket wire springs for fast lock-time and reliable discharge with factory or military ammo (not recommended for use in 5.45×39).
It’s worth noting that this is the only drop-in trigger unit on the market that isn’t contained within a CNC machined housing. Wilson Combat’s drop-ins are housed in a block of machined billet steel, and the rest of them are housed in billet aluminum. I actually like CMC’s idea of using a piece of sheet metal bent into shape. Quick, easy, sufficiently effective, and definitely low cost. But as CMC is no longer king of the budget hill, it looks less appealing.
Obviously I can’t actually say what sort of steel the FCG parts are made from, or how they’re machined. In this day of wire EDM machining, though, tolerances of one thousandth actually seem loose.
Many of the other manufacturers flaunt the fact that they use full 1/4″ width disconnectors. I’m not sure I’m likely to put enough rounds through a trigger to prove or deny the claim of additional durability from that increased engagement surface, but have brought it up thus far so it’s worth mentioning that the CMC unit employs a rather skinny hammer and a very skinny disco.
Pull weight is set at the factory. There is a 3.5, 4.5, 5.5, and 6.5 lb option, with each available in curved or straight trigger shoe flavor. My example is a 3.5-lb unit, and my Timney trigger pull gauge pegs it at a very consistent 2.75 lbs. Pre- and over-travel are also taken care of at the factory, so the only thing remaining is to drop it in and go shooting.
Unfortunately, CMC Triggers’ triggers lack one feature that I definitely value — a means by which to tension the unit inside of the receiver. Although this ends up being a fairly small nitpick in practice, if you check out the video above you’ll be able to see and hear how the trigger pack wiggles inside the receiver. As they really must be to account for receiver and trigger pack tolerances, the bushings in the trigger unit through which the trigger pins go are slightly larger in inner diameter than the pins are in outer diameter. With no way to clamp the trigger unit down, it wiggles on the pins. It’s the only drop-in trigger on the market, at least as far as I know, that doesn’t attempt to take up this slack somehow. If this were my trigger, I’d put tape under the rear of the housing until it had to be compressed with a few pounds of force before the trigger pin could get through.
On The Range
To maintain continuity across all of these drop-in trigger reviews, including the ELF review and Velocity review already published, we’ll rate them on the same metrics. For definitions of the following trigger fundamentals, please see that ELF Tactical review.
- Take-up, which is also referred to as pre-travel or slack. The trigger itself has no take-up. It’s a single stage and it’s right up on the sear at rest. However, it may or may not have rearwards wiggle room depending on how it’s positioned on the pins. That click can feel like a millimeter of take-up.
- Creep. Most of the time, there was no detectable creep in this trigger at all. A few times, a hint of creep was detectable and visible. A little awkward that it wasn’t totally consistent, but it’s still like 99.5% flawless here.
- Break. Possibly due to the pull weight of only 2.75 lbs on my example, the break has a light feel to it. However, it’s pretty dang crisp and very nice. It goes from 2.75 lbs to 0 instantaneously, and that’s what we’re looking for.
- Overtravel. Short, but room for improvement. It’s pretty solid at the back, but doesn’t have the same steel-on-steel feel of some others.
- Reset. Smooth trigger travel forwards to a click that is on the light side but still audible and tactile. There were a couple of instances where it felt like it caught at the end — like the disconnector didn’t want to let go — but only when I was releasing the trigger in an exaggeratedly slow manner to get a feel for it.
- Pull Weight. Plenty of options from the factory, although the 3.5 lb and 4.5 lb ones seem to be most commonly stocked by retailers. I’ve seen the 3.5 lb one advertised as “3.0 to 3.5 lb,” but, again, mine measured a totally consistent 2.75 lbs.
I shot some IMI 5.56, Federal 5.56, and a bunch of Silver Bear .223 with the CMC trigger installed, and it had no issues with any of it. Despite their fairly hard primers, they had acceptable dents. The trigger was totally reliable for me throughout, both suppressed and unsuppressed.
The look of CMC’s flat trigger blade may be a little extreme, and I’ve seen folks express concern about how it might feel with that hook on the bottom, but I’m happy to report that in practice it feels great. That hook or flange causes no discomfort whatsoever, and it has the benefit of providing an index point for your index finger. A couple other triggers on the market employ similar — if not more visually-pronounced — methods of ensuring consistent trigger finger placement, as this fosters accurate, consistent shooting.
Thanks to a much cleaner break, lower pull weight, and less overall travel with none of the grit, the CMC unit is significantly faster than a mil-spec trigger. It’s also easier to shoot it accurately, whether shooting quickly or making slow, precise shots from a rest.
The CMC trigger is good enough that if it shipped in a rifle I bought, I wouldn’t replace it. That said, with the entry of the Velocity Trigger to the market, I can’t see spending more money on the CMC since it has fewer features, lower build quality, and falls just short of the Velocity on trigger pull fundamentals. It doesn’t quite have the same crisp, solid feel. It’s really dang good! But it’s a bit softer around the edges.
Bottom line for me is that the CMC needs to once again claim the title of least expensive drop-in trigger. It would still be a solid choice at the right price. Conversely, some changes to build and features could make it more competitive at its current price. It’s still a known quantity and a popular trigger and there’s a lot of inertia there, but it’s roundly beaten in every last category by Velocity’s unit.
RATINGS (out of five stars, compared to other drop-in AR triggers):
Fundamentals * * *
Average or even slightly above average for this group of drop-ins. No creep and a nice break.
The only drop-in of 10 that doesn’t attempt to eliminate wiggle in the receiver. No other adjustments are available either. Skinny hammer and disconnector. Sheet metal housing.
Price * * * *
Second lowest MSRP for a drop-in AR-15 trigger that I know of.
Overall * *
Price would be the redeeming factor here, and if it were the least expensive option by a decent margin I could be convinced to rate it above average. However, a better trigger is readily available for $40 less. To be clear, in comparison to the entire AR-15 trigger market and certainly in comparison to a mil-spec trigger, the CMC drop-in is great. This rating is against the other 8 drop-in triggers that I have here, where it’s slightly above average on fundamentals but has the lowest build quality, least features, etc. It’s just outclassed in this specific group, so comes in just below average overall.