Midwest Industries Enhanced AR15 Flat Trigger Review
The AR15 has grown into the most customizable and most popular rifle in the country. While some upgrade are mostly cosmetic, one of the easiest ways to make a rifle easier to shoot well is to upgrade the budget minded, often lawyer approved factory trigger. Midwest Industries has added another contender to the list of trigger options with their Enhanced AR15 Flat Trigger. This is a cartridge style trigger with an anodized aluminum frame that holds S7 steel internals. S7 is a high-end shock resistant steel that is used in tool and die work. The trigger comes with anti-walk pins and all the hex wrenches needed for easy installation.
The first step in upgrading to the MI Enhanced AR15 Flat Trigger is removing the pistol grip, even if it seems like a strange place to start. ARs use the pistol grip to hold the safety spring and detent in the bottom of the receiver. A 3/16″ hex wrench is the easiest way to reach up inside the body of the pistol grip and loosen the single, large bolt used to hold the grip in place.
Once the bolt is out, slowly wiggle the grip down from the receiver. This is best done with the barrel facing towards your right, as this makes it easy to see the spring and detent hiding above the pistol grip. Take a bit of time with this step, as chasing springs and detents around the workshop is even less fun than it sounds. Set these parts aside, as we will need them for reassembly later.
Next, use a punch to press out the front trigger pin, which is the one closest to the magwell. The hammer is held in place by this pin. It is under spring pressure and will likely pop out when the pin is pushed free and the punch is removed.
The rear pin will need to come out next. We can use the punch to push out the rear pin and remove the rest of the trigger assembly. Once all the parts are out, the pin can be pushed back through the trigger and sear assembly to hold everything together. A pro-tip is to put all of these trigger parts together in a small Ziploc bag with a label. There is an unwritten rule in the AR15 world that if you can upgrade your existing AR enough to collect more than 50% of the parts in zipper bags as spares, then you are entitled to use all these spare parts to start the build on a new rifle. So, keep these somewhere safe, as you are now off to a good start.
The safety selector needs to be removed next. If your rifle has a standard selector, then it should come out by hand. The AR on our bench has an ambi selector, so we’ll need to use a hex key to remove one side before it will drop out.
Before adding a new trigger to any rifle, I like to put a light coat of grease on the contact surfaces. Our current go-to gun grease is Black Rifle Balm. While there are certainly other products that work, we have been having good luck with this one recently, even after a little sticker shock. Black Rifle Balm was actually designed with guns in mind instead of being a repurposed roller coaster lube.
Now that all the old, factory parts are out of the way the Enhanced AR15 Flat Trigger literally just drops right into place. For new builds instead of upgrades, just start here and slide the trigger into the lower. Cartridge triggers are as easy as it gets.
When properly seated, the Enhanced AR15 Flat Trigger should look similar to the picture, as shown above. The edges of the red aluminum cartridge are well below the top of the lower. The flat trigger face is down inside the trigger guard, under the receiver. Also note how the flat face of the hammer is pointed towards the magazine well.
The pins that are included in the package are “anti-walk” trigger pins. These are secured to the lower with screws that have heads which are slightly larger than the trigger pin holes, so the pins cannot work their way out under fire. Before putting the pins into place, I like to coat the threads with Vibra-TITE VC-3 which I think is a better fit for this kind of work than Loctite.
When the anti-walk pins are properly installed, only the screwheads will be visible on the sides of the receiver. Resist the urge to dryfire the trigger at this point as the hammer is much tougher than the aluminum at the back of the magazine well. The fix for dry firing without an upper receiver attached is an AR trigger test fixture which catches the hammer before it impacts the lower. These test blocks can even be 3D printed for “free”.
Now that the new trigger is in place we can re-install the safety, which is just the reverse of removing it. For ambidextrous safeties, do not forget to attach the second selector switch. Then, re-attach the pistol grip with the safety spring and detent.
The last step and the only one that can be a bit finicky, is adjusting the two setscrews that take any wiggle out of the trigger assembly, depending on who made your lower receiver. The 5/64 Allen wrench is included and the screws only need to be finger tight. This step got a lot easier after we grabbed a small, flat head screwdriver to scoot the spring legs out of the way. This fixed our trouble spot so we could get the end of the Allen wrench down to the setscrews.
The MI Enhanced AR15 Flat Trigger is nothing short of a huge improvement over the common AR factory trigger. It has a smooth pull, crisp break and really short reset. If overtravel bothers you, it seems like the MI trigger barely moves during the whole firing cycle. In addition to letting multiple shooters try the new trigger, we were also able to pair it up with the Blackbeard AR Dry Fire System and it ran like a champ. If you are looking for something that has been tested to be compatible, this one works. While curved vs flat is certainly a matter of personal preference, this trigger holds its own against anything else that we have ever tested.