I get asked a metric crap ton of questions. It’s something that I’ve become accustomed to. Usually these questions are about clone service rifles or dissipators. Lately a lot of people have been asking about or mentioning the FM15 Gen 2 upper that I bought to review. Who can blame them. I’ve had it for well over a year and I’ve been promising a review. Some things take time and I think now is finally the time.

First things first, I need to disclose some things before I delve into the details. I purchased this upper receiver with my hard-earned money, but I was fortunate to receive a 13.9” upper from FoxTrot Mike for free. This review will focus on the 11.25″ upper that I bought and not the 13.9″. That one will come later as I have some cool plans for it. Throughout the process of this review, I did receive some parts from Foxtrot Mike for free as well.

A Quick Overview

If you missed my original post about the FM15 Gen 2 upper, then here is a quick overview to get you up to speed. In the world of AR15 enthusiasts, the quest for the ultimate side folding AR15 has led us to some intriguing innovations, and the FoxTrot Mike Gen 2 upper is no exception. This intriguing upper takes the fascination with side folding to a whole new level by enabling you to fire your rifle even with the stock folded.

Side Charging Upper

One standout feature of this upper is its side charging mechanism with a non-reciprocating charging handle. This design eliminates the worry of hand positioning and the potential discomfort of a charging handle smacking into your hand during operation or causing malfunctions due to impeding the charging handle. Personally, I find it intuitive to hook my thumb over the charging handle, using it as a lever to drive the gun effortlessly.

Ridgid Handguard

The proprietary 10.5″ handguard deserves special mention for its ingenious design. The entire upper has a taller profile, accommodating the side charging function. Consequently, the handguard is also taller than a standard AR15 handguard. FoxTrot Mike employed a lengthy barrel nut, tapered to lock securely onto a corresponding taper on the barrel. This taper not only ensures a tight lockup, but probably also aids in maintaining concentricity to some degree.

The impressive rigidity of the handguard cannot be overstated. It surpasses many other handguards, making it ideal for mounting lasers. Moreover, the handguard cleverly interfaces with a notch in the upper receiver, akin to an HK416, effectively preventing any rotation. With these features combined, the handguard stands as a veritable fortress of stability.

Barrel and Gas System

The barrel and gas system also have a fair amount of features adding value to this upper. The upper comes equipped with an 11.25″ carbine gassed barrel, chambered in 223 Wylde, and sports a 1:8 twist rate. Starting at the tip, the barrel has wrench flats machined into it. This allows you to spin on and off muzzle devices safely without the aid of a reaction rod or similar tool. The gas block is both keyed to the barrel to ensure perfect alignment with the gas port and it is also pinned to the barrel for a bomb proof attachment.

When I first got my upper it had a standard non-adjustable gas block. The gas block has since been swapped for FM’s adjustable gas block after a conversation with Paul from FoxTrot Mike. Normally I’m not a fan of adjustable gas blocks on hard use guns. This gas block is more like something you’d see on a hard use piston gun. It’s got positions for adverse, normal, and suppressed shooting. There’s no inbetween and no way this thing is coming out of adjustment. Perhaps the only con of this gas block is that it is hard to change positions.

Bolt Carrier and Recoil System

The bolt carrier, as stated in my post on my initial impressions, is incredibly short in comparison to a milspec carrier. In fact, it’s only about half the size. This is due to the fact that the bolt needs to fully reciprocate and pick up a round without short stroking inside of the upper. It no longer has a buffer tube to get the travel it needs. Its very much similar to the old school ZM Weapon Systems LR-300 in terms of its bolt carrier. The shortened size and reduction in weight helps produce a soft and rather smooth recoil impulse.

Aiding in the smoothness is the fact that the bolt carrier also rides on a sort of guide rod that the recoil springs (what would be the buffer spring in a normal AR15) nest together on. This rod goes through the top of the carrier key, effectively helping guide it straight backward and retaining the recoil springs. The carrier key itself is taller than normal. The top of the key interfaces with the guide rod, while the bottom of the carrier key interfaces with the gas tube. Having a much taller carrier key might be a concern to some people as one might think it would cause issues with breaking carrier key bolts. You can dismiss this concern as the carrier key has a built in recoil lug that interfaces with the carrier, effectively sparing the bolts from any forces acting on the carrier key.

What Comes In The Box

A close up of the piccatiny adapter. You can see the hole where you can access the rear takedown pin spring and detent.

When you get your hands on the FoxTrot Mike Gen 2 upper, you’ll find the box is stuffed full of Foxtrot Mike goodness. First and foremost, the instruction manuals are like novels in their own right, covering everything from the break-in process to routine maintenance and everything in between. These comprehensive guides prove incredibly helpful in familiarizing yourself with the upper’s workings. I highly suggest you take the time to read them as this upper is very different from a milspec upper. It can save you a few headaches.

Provided in the box is a set of rail covers. These covers are reasonably grippy and they help insulate your hands from heat. If you do a lot of suppressed shooting, then you’ll grow to appreciate them. I used some BCM rail covers instead, but they were definitely a nice touch if you don’t already have a set that you plan on using.

FoxTrot Mike includes a rear piccatiny adapter for your lower receiver. This allows you to attach the foldable stock of your choice. It is a two part adapter. The side with the pic rail keys into the lower like your rear end plate would, while the other part threads into both the other part of the adapter and where your buffer tube traditionally attaches. When you tighten down the inner portion it sucks the rear part of the adapter tightly to the lower. Then the buffer retainer locks the threaded portion in place, preventing it from loosening up. One notable feature of the adapter is that it has threaded hole that simplifies the installation of the rear takedown pin detent and spring while the adapter is in place.

I did get a folding stock adapter from FM which has a hinge mechanism rather than piccatiny. This allows you to attach a buffer tube to the hinge mechanism and still use your favorite regular AR15 stock or brace. At that point in time the folder was pre-production. The folder is very robust and you’d probably have a hard time breaking it, although during my testing some people have had a hard time unlocking it.

Testing the FM15 Gen 2

I know what you’re thinking, and you’re right—I’m here to tell you how the FoxTrot Mike Gen 2 upper held up during over a year of testing. So, let’s dive right in.

To truly put this upper through its paces, I spared no effort in pushing it to its limits. However, let me make one thing clear—I didn’t resort to absurdly unrealistic scenarios like dragging it behind my car, smashing it with a hammer encased in a block of ice, or force feeding it mud. That’s not how real-life firearms are used, and such tests provide limited practical information. The FM15 upper was heavily neglected in terms of maintenance. It was often left dirty, filled full of carbon, and dirt. In fact, it was only cleaned when I broke something and I needed to work on it and when I sent it into Foxtrot Mike to install the adjustable gas block. I didn’t want them to have to deal with a filthy gun. I did periodically apply to Extreme Weapons Grease to the BCG about every 1000 rounds.

To set the stage, I only purchased the upper itself, assembling a custom lower tailored to my preferences. This allowed me to install FoxTrot Mike‘s folding mechanism on my lower. The installation process, while not overly complicated, did take some getting used to. I discovered the importance of proper installation as an incorrectly installed adapter led to bolt short stroking. Luckily, Paul and Neal from FoxTrot Mike provided support, guiding me through the adjustment process. This was one of those scenarios where reading the instructions would have been beneficial.

Running drills and in general just trying to break things.

My testing involved shooting the hottest ammo I could find. I wanted to see if I could beat the gun to death. Throughout, the upper experienced nearly 100% of its shooting with a suppressor, and I made sure to shoot it in all drills and scenarios I’d subject my go-to rifle “Redacted” to. While I didn’t expect it to perform at the same level as my higher-priced firearm, I was pleasantly surprised by the results. In my effort to break any portion of the bolt carrier or cause mechanical failures, I experienced no breakage, cracking, or unusual wear on the BCG.

As previously mentioned in my initial impressions, there is a small gap between the carrier and the back of the ejection point. Naturally, this raised concerns regarding potential debris ingress. However, I tested the upper in realistic scenarios, subjecting it to dirt, silt, and more. Despite these challenges, I’m delighted to report that no debris caused any stoppages in the firearm. The FM15 Gen 2 upper proved its resilience in this aspect. I will note that the gun often ended up absolutely filthy. It was often completely filled with both carbon and dirt. That also never caused any failures.

Outside of a couple instances, the FM15 Gen 2 upper was very reliable. Every rifle will have stoppages, double feeds, and the occasional hiccup when you run it hard and neglect it. It happens, but it shouldn’t be a normal thing. Under normal circumstances, I can count the number of malfunctions on one hand, but they did happen. I’ve had a couple double feeds and that’s really about it. With all that said, I did have that issue where I improperly installed the rear pic adapter, I did break it once, and I did wear out some stuff. I’ll cover all that in a bit.

How Did It Handle?

I shoot a lot of guns. Everything from KAC, Colt, FN, LMT, Clones, Dissipators, HK’s, down to PSA’s. You could say I’m a HUGE gun snob. You could hand me any AR15 and I can run it just as good as any other AR15, but it’s the little nuances in its handling and performance that really interest me and drive my opinions about rifles.

One of the first things that caught my attention was how smoothly the gun shot, even with a suppressor attached. The recoil wasn’t as aggressive as I anticipated, and the gun handled well with excellent balance. It was incredibly easy to run fast and the gun stayed reasonably flat. Part of this mild recoil and flatness can be attributed to the bolt carrier mass or lack thereof. The rifle really shined in this regard without the suppressor, but in the interest of being abusive, I ran a suppressor nearly 100% of the time. The adjustable gas block did to a good job of toning the gun down with the suppressor as well.

The manual of arms for this upper is definitely different. You will experience this every time you move from a platform you’ve been on for a long time to a new platform. At first I often found myself going to the back of the gun to charge it. Of course that doesn’t work when there is no charging handle there. It just takes some getting used to though. Side charging from the handguard actually proved to be really nice and just as fast. The factory charging handle leaves a bit to be desired in terms of comfort. I ended up running an Applesauce Engineering charging handle. It is an amazing option if the factory charging handle isn’t your favorite.

The complete package, while not light at 8.2lbs as setup, balances incredibly well. It points quickly as you’d expect it to. As mentioned before, the rifle is easily driven when you throw your thumb up over the top of the charging handle. Moreover, when folded, the gun fit neatly into my Vertex backpack, making it my go-to backpack gun in my get-home bag—a testament to my trust in its performance, even competing with my MP5K for that position.

Some people are going to fixate on accuracy. I might disappoint here. I did not sit down and shoot groups with this gun. I ran a lot of drills and tried to beat the gun to death. I will come back with a sit down report on how the gun groups later, but it was the least of my concerns. Why? Throughout all the abuse I put it through, I never saw a difference in what I expected accuracy wise or anything concerning. I basically shot the same as I would with any of my go to guns. It was good enough for me to score hits consistently out to 400 yards on man sized cardboard and place rounds where I needed to during up close drills.

The 11.25″ FM15 Gen 2 upper and folding adapter is short enough to fit into a medium sized backpack folded without the suppressor attached.

Alright, What Did You Break?

The First Time Was My Fault…

The FoxTrot Mike FM15 Gen 2 was mostly sunshine and rainbows… unicorns even. Not completely though. I think this is the most important part of the story. Not because I’m pointing out things that broke, but because of how Foxtrot Mike handled it. While the gun was running, it ran incredibly well. Mostly boringly reliable, very easy to shoot, and an all around pleasant experience. I did have some hiccups though. The first being the bolt not locking back on empty.

Little did I know that this problem was actually my fault. I should have read the instructions. It was actually a simple fix. The problem ended up being the way I installed the folding adapter on the back of the gun. As previously mentioned, its a two part adapter. The rear portion of the adapter butts against the rear of the lower and keys to it like an end plate would. The other section is threaded and threads to both the back portion of the adapter and to where the buffer tube threads into the lower. When you tighten the inside part, it sucks the whole system to the back of the lower. It is possible to assemble it in such a way that the inside portion impinges on the bolt carrier’s movement and that is what I had done.

Paul and Neal at FM educated me on the proper installation of the folding adapter. It was at this time it was pointed out to me that there was actually a set of recoil springs made specifically for suppressor use. I had not been using them and had been running the gun hard with a suppressor. Paul mailed me a set of the springs and offered to install their new (at the time) adjustable gas block on my upper. This would eliminate the need for the suppressor specific recoil springs, which I never used. He also ended up sending me a 13.9” upper, which I plan on pitting head to head with “Redacted” to really give a good benchmark of its performance.

Kronk Smash…

The next thing I broke was the folding adapter, but not at the hinge. I broke the interior threaded piece. Some of you may have seen the pictures my friend posted on Weapon Malfunctions before I had him take them down. In all transparency, I felt as though it was not fair to the guys at FM, the upper, or this review to have those pics posted with absolutely zero context. At the time I was not ready to release any sort of review or statements on the upper and I think those pics require the context of this post, so the only logical option was to have the pics taken down.

During a decent day of shooting the adapter ended up breaking after I mortored the rifle off of my leg to clear a double feed. All rifles malfunction and the double feed was a one off non-issue. Malfunction clearing practice if you will. However, when I went to continue my drill, the brace and folder fell off the back of the gun. I reached out to Paul and I discovered that I was the second person that they had heard of this happening to. The threaded portion of the adapter was made out of a delrin like material. Paul ended up sending an aluminum version of that threaded part.

I am under the impression that the aluminum part is available. Either way, I haven’t seen much in the way of other people breaking the delrin part. If this concerns you, I would definitely check with FM to see if you could get the aluminum part. The 13.9″ upper currently uses the delrin part. If I break it, then I’ll report back.

After mortoring the gun off my leg the inner delrin threaded section of the adapter snapped in half. It was remedied with an aluminum version of the part.

Worn Out Springs

The last and final issue I had was just north of 4500 rounds. I started having light primer strikes that happened more and more frequently. After checking the trigger for debris, I found none. I had swapped triggers in the lower and tried a handful of other things to resolve the issue. Nothing worked and I was baffled until I handed the gun off to a friend to shoot. At which point upon watching the gun, I discovered that the gun wasn’t completely going back into battery. This lead me to the cause. I had worn out the original recoil springs. Keep in mind that I abused this gun, filled it full of dirt and carbon, neglected it, and ran it suppressed on some pretty hot ammo with the springs that were not designed to be run with suppressors. I did have the adjustable gas block on it, but it had been run a substantial amount of time with the non-adjustable gas block and the wrong springs. Essentially I had worn them out.

After acquiring a new set of recoil springs, gun ran flawlessly again. I have yet to have any issues since.

Overall Impressions

I was incredibly excited to get the FM15 Gen 2 upper. The idea of having a folder that I could shoot folded was intriguing. Little did I know, but I would take it and later repurpose the gun as my backpack gun for my get home bag. That was back before the pistol brace rule and I could legally conceal it as a pistol.

I think this FM15 Gen 2 upper fits in an interesting niche. Originally when I had heard rumblings about a short 8.5″ 300blk offering, that was what I was interested in. Unfortunately, that didn’t come to fruition and I’m not sure if they even offer anything of the sort currently. That drove me to get the 11.25″ 223 wylde upper. The 11.25″ barrel has a bit more oomph than something like a 10.3″ 5.56. Inside 400 yards the gun performs quite well. It can push out and perform past that, but I think it shines inside 400 yards. It’s all a game of trade offs. I can say that I do love my 9.5″ 300blk LMT, but it doesn’t fold or fit in my get home bag. The FM15 Gen 2 just does most things reasonably well. You can take this gun and make it tiny, all while still having the ability to reach out and touch things effectively.

I have this gun setup to run under nods. Despite that, it balances out very well and it is also reasonably light. It should be light and handle well due to its shortness, but I have other short guns setup to run under nods and they are not as balanced or as light. Impressively, its not front heavy despite its incredibly stout handguard. Being light and pointable is huge. In fact, I think this could make a great gun to compete with in things like 3 gun.

This might be a controversial take, but I think that this upper could take on some serious roles. There are a ton of arm chair warriors out there that proclaim things like, “you must own a KAC and nothing short of a KAC is acceptable for duty use.” That couldn’t be further from the truth. I’d say, don’t trust your life to any rifle that hasn’t proven itself to you. Also, have reasonable expectations. I ran the FM15 upper in a dirty dusty desert environment. An urban environment might be far easier on the gun and hence why I threw mine in my get home bag. It proved itself in the dirty environment that I ran it in and I feel comfortable running it in in my get home bag.

Outside of the 3 issues I had previously mentioned, my FM15 has been reliable. Especially when I’m cleaning it and have it on an actual maintenance schedule, like I currently have it. Would I run it as a hard use gun in some fictional SHTF situation with a million variables? No… I’d run my KAC SR-15, any of my Colt based clones, or Redacted before I’d run the FM15, but I have all those at my disposal and they’re far more proven. If all I had was the FM15, then I’d run it hard and not look back. I’d say if it proves itself to you, then go ahead and run it because it’ll work great.

The FM boys

I do want to give a big thanks to Paul, Neal, and the boys at Foxtrot Mike. I tried to review their upper as objectively as humanly possible and in the end despite the few issues I had, I feel like its a great upper. More importantly than the product that they produce, is their excellent customer service and devotion to their customer base. They absolutely went out of their way to help fix things even before Paul knew that I was reviewing his upper. When I say they went out of their way, I mean they really went out of their way.

Paul and crew jumped every time I had an issue. Paul personally answered every question I’ve ever had both incredibly quickly and very thoroughly. On top of that Paul also went above and beyond every time anything came up. All of his guys did. In fact, I have a pile of spare parts that I’ve accumulated over my various interactions with him that he just tossed my way. I’ve never needed them, but he sent them. I appreciate that greatly.

In the big scheme of things, this blog is a hobby. In my professional life (gotta have a real job to pay for all this stuff…) we have a series of standards by which we operate, especially in how we communicate. I pick up on these same practices and the professionalism or lack thereof when I deal with companies. One thing that I greatly grew to appreciate was this same level of communication and professionalism that I expect at work when dealing with the FM boys. It wasn’t just a conversation where all the right things were said. It was the professionalism, making time to handle things, being kept in the loop when things happened, following up, ect. Being CC’d on an e-mail here and there and getting a video progress report on my upper was more than I had ever gotten from any other company.

I give The Foxtrot Mike crew a 10 out of 10. They are a hard working bunch of guys that truly do appreciate their customers.

Wrapping it up…

This review has taken a long time and been quite a process. In the end it was an adventure. It not only lead to me satisfying my curiosity about folding guns, but it gave me a backpack gun for my get home bag. While there were a few bumps in the road, the overall experience was pretty good.

The FM15 Gen 2 has been over all fairly reliable. Yes, there were some hiccups. I don’t feel like they’re things most people would have to worry about though. If your piccatiny adaptor is installed correctly, then there’s no issues. I’ve yet to see anyone else break the folding adapter and now they have an aluminum part that cures that issue. I am pretty positive I only wore my springs out because I ran them suppressed and didn’t use the correct springs. I literally tried to beat this gun to death. My goal was to break it. I did succeed, but it was only under some incredibly abusive circumstances that most people probably wont replicate. In fact most normal people never push their equipment that hard. Outside of those few things, I would consider it boringly reliable. It gets my stamp of approval there.

The gun handled incredibly well. After getting used to the manual of arms, it became intuitive and easy to use. It’s super comfortable to throw your thumb over the charging handle and drive the gun hard. It’s also so soft shooting and controllable that it is incredibly easy to shoot. Even with a suppressor the rifle is very mild. Overall, the gun is incredibly fast and an absolute joy to shoot. On top of that, Foxtrot Mike’s customer service is on a whole new level and a lot of other companies should really start taking notes.

I did mention that Foxtrot Mike sent me a 13.9″ upper, which I currently need to finish setting up. While normally this is not a big deal, this time the setup has to be very specific. The plan is to pit the FM15 13.9″ against a build that I did. This build was lovingly dubbed “Redacted” as it was kept off the blog and IG while I put it through its paces. Redacted still hasn’t been posted on the blog. It will be soon though. I plan on comparing the two head to head under various situations to see how the 13.9″ compares under some hard use. Stay tuned for that.