CMC tactical AR-15/10 trigger group

When I first spec’d my AR, I decided on getting a fairly solid foundation by being careful about selecting the things that were harder to change like the barrel weight and twist rate. Plus a bit more tight-fisted with those things I could change more easily. This meant that the trigger in my delivery spec gun was rather basic. For me, this was the main factor affecting the feel of the gun, so I considered my options:

CHOICES, CHOICES

Get a competent gunsmith to work on the trigger; maybe not! As I’ll be without the gun while the work is being done and it’s usually more costly to pay for an expert’s time on an individual basis. Do the work myself; definitely not! I might easily over assess my capabilities in a number of fields, but I readily admitted to myself that this would not be in my area of competence. Get a replacement trigger kit! This might be a possibility – I’ve done it before with my Ruger 10/22, but I hate working with small springs that seem to jump eagerly into another dimension when I’m not looking. Finally get a drop-in trigger unit? Now we’re talking. No risk of losing small components and the quickest and easiest option (for me, at least).

So with that decision made, I now had to select an individual product. After a quick bit of internet research, I had a shortlist. I won’t bother to list them all here, but if you’re really curious then you might want to Google ‘AR drop-in trigger units’ or similar terms. Being an impatient person once my mind is made up, I decided to visit my local RFD (Neal Parnham) at Suffolk Rifle to see what was immediately available. A brief chat with him confirmed the suitability of my selected option and I settled on CMC’s Tactical AR15/10 Trigger Group. This gave me: single stage action, curved blade, 3.5 lb pull (more on this later), small size pins (not suitable for some Colt lower receivers) and standard length posts for use in mil-spec lowers.

OUT WITH THE OLD

Removal of the old trigger components was fairly easy, but some parts are spring-loaded, so it’s always sensible to wear eye protection and to work in an uncluttered environment. Usual disclaimer – if you decide to take this route, you should follow the instruction supplied with your choice of new trigger. But in this instance, the preparation steps were:

• Remove magazine and verify that the weapon is unloaded
• Remove the upper receiver from the lower receiver and set aside
• De-cock the hammer (but don’t let it strike the front of the receiver)
• Remove any circlips that are retaining the hammer and trigger pins
• If necessary, use a non-marring (brass or plastic-tipped) punch and light hammer to move the pins. This will allow you to remove the hammer, but not the trigger yet
• Loosen the grip screw located inside the grip to allow the handle (grip) to drop between a quarter and half an inch. This will allow the safety catches retaining spring and plunger to disengage. Conversely remove the grip and take out the aforementioned spring and plunger.
• Low pull out the safety and then the trigger

IN WITH THE NEW

The installation steps were a lot quicker and easier:

 

• Screw two of the provided hex screws (no tiny circlips to jump away and hide!) into one end of each of the pins supplied in the trigger kit
• Lower the CMC trigger assembly into the receiver
• Insert the pins and secure them on the far side of the receiver with the remaining two of the hex screws provided
• Reseat the safety, making sure the safety lever is properly oriented
• Insert the safety detent pin and spring, re-install the grip, and tighten it down

ONE LITTLE PROBLEM

The only installation problem I experienced was that the pins were fractionally too long. This meant that even when the retaining hex screws were fully tightened, things were a little bit loose. Taking a micrometer to the part of the lower receiver on either side of the trigger, showed that it was a few thou’ narrower than on a mil-spec AR that Neal had in his workshop.

This left a tiny bit of sideways slop in the unit, but the beauty of a drop in unit like this is that the trigger does not rely on those pins to function. They are there to hold the housing in place, nothing more! Rather than shorten the pins – I was concerned about the hex screws bottoming out if I removed too much – I opted for the quicker (and reversible) solution of using small steel washers (see photo). Once these were added, the whole assembly tightened up nicely. The CMC is made to fit a cross section of AR15 lowers and I would guess thta the SGC lower, which is built in-house might be just a shade slimmer than you might encounter on a commercial design.

DOH!

Now, there was just one other little issue that I have to own up to! In my haste to get the job done in time for the Introduction to a CSR course I’d booked myself on, I hadn’t bothered to check on the minimum trigger weight allowed for the Service Optic class that I want to shoot. The 3.5lb pull trigger that I had installed is 1lb too light. OK, so I could switch to the Practical Optic class, but I didn’t want to. Sensibly CMC offer a number of pull weight options 3.5, 4.5, 5.5 and 6.5 lbs and Neal has ordered me a 4.5 for a one-for-one swap, so no problems.

NAME: CMC Tactical AR-15/10 trigger group
PRICE: £199
CONTACT: Suffolk Rifle Co, 01473 730035, www.suffolkrifle.com