Foxtrot Mike FM9B Accessories [TOP 10 LIST]

Over the past few years, the concept of the pistol caliber carbine has really taken off. These weapons, usually in 9mm, are light and handy carbines that are great for competition. Coming in the same form factor as rifles, they’re much easier to shoot and get around one of the biggest problems with pistols, which is that they are hard to shoot well due to having to hold them out in front of you with your hands. Pistol caliber carbines also innovate on the idea of a rifle, by keeping things light with a short barrel, and often some kind of folding stock. These come, conceptually, from a longstanding military want for a firearm that can be issued to people like guards and tank drivers who don’t necessarily need or want a full-size rifle, but might well need something with a bit more firepower than a pistol. Thus, we have the M2 carbine, the grandfather of modern pistol caliber carbines. This article will discuss a modern pcc, the Foxtrot Mike FM9B, with a comprehensive list that will make your next FM9B accessory purchase as easy as possible. 

Things have come a long way since the 1940’s, with many pistol caliber carbines being well made, easy to use, and great fun as a competition firearm. They’re also a really good option for a home defense carbine, for the exact reasons I listed above. In this piece, we’re going to be talking about the Foxtrot Mike FM9B, which is basically a really well made AR9 that comes as a complete pistol caliber carbine. With a highly tuned, well-made pistol caliber carbine, you’re going to need some accessories. In this list, we’re going to cover ten accessories we think will come in really handy on your new pistol caliber carbine.

Here, we’re going to try to recommend everything we think you need to get yourself on target and shooting both quickly and accurately. So, we’ll recommend the sights and lights that we find are a great fit for this carbine. After that, you’ll need mags grips, and slings to keep things handy and putting rounds down range, where you want them. Finally, a few quality of life upgrades, such as two stage trigger and an ambidextrous charging handle can make a perfect FM9B accessory.

Magpul Mbus Gen 2 Sights

magpul sights FM9B

The FM9B comes optics ready. This means that, out of the box, it does not have a sighting system and that you’ll have to supply your own. Most people will put a red dot on their pistol caliber carbine, and we’ll certainly get there, but we’re starting with something simpler here. These are the Magpul MBUS sights. Basically, they’re a set of iron sights that attach to a section of picatinny rail that allow you to fold them down and out of the way when you don’t need them, thus being labeled as backup sights. With that said, if you’re looking for simple and just want some sights, these would do just fine as your primary sighting option as well, and many people run these in that manner in their AR platform rifles.

Also, these are a standard height that works well with most red dot sights, making these a great backup in case your red dot doesn’t work when you need it to during competition or home defense. Frankly, it always makes us uncomfortable to see weapons without iron sights that people might want to use for home defense. Lights and lasers fail. Batteries die. Are you willing to bet your life on a battery made in some giant factory in a far away place? Neither am I. Thus, we think it’s always smart to put a set of non-electronic sights on any weapon you might use to defend yourself from harm. These are rugged, install easily, and are a great FM9B accessory.

Butler Creek Black Sling

black sling FM9B accessory

Keeping things similarly simple for our second recommendation, we’re calling for a sling to be your FM9B accessory. A pistol caliber carbine is a deeply practical weapon given its light weight and handiness. With that said, you’ll probably be getting it to run in competition or as a home defense weapon. In either of those cases, a sling is a must, both as a means to carry the weapon and to be used as support when shooting from standing or kneeling positions. This one, by Butler Creek, is a simple black sling that goes through standard sling loops, which you would need to get separately. It’s made out of a tough nylon so that you can set it up on the gun and forget it’s there until you need it, which we think is just about perfect in a sling.

Glock 33rd Magazine

GLOCK G17 9mm 33rd FM9B

Of course, with any firearm you’re going to need a way to get rounds into the gun. A major benefit of the pistol caliber carbines that are coming out these days is that many of them take readily available Glock magazines. The FM9B is no exception to this. Conceptually, this goes beyond simple economics and has major benefits for those in competition matches. If you run a pistol caliber carbine as your rifle, and a Glock as your pistol, you only have to carry one kind of magazine, which will cut down on weight and increase speed.

For the FM9B, which comes in some really cool finishes, we like the look of the flat dark earth Glock magazines. In particular, we recommend the 33 round OEM magazines. While these might be a little long and bulky for most pistol applications, they feel right at home on a rifle format weapon making them a great FM9B accessory.

Streamlight TLR-8A Tactical Light

Streamlight TLR-8 A FM9B accessory

Speaking of pistol compatibility, we’re recommending another pistol accessory on this one. In this case, we think it’s a great idea to have a light on the gun in that it would make a great home defense weapon and we like to avoid shooting literally in the dark. Instead, mount something like this Streamlight, which packs a lot of features into a small package. This light, meant for pistols, mounts on standard 1913 rail and is a great FM9B accessory. In that light frame, you get a 500 lumen white light and a red laser. We think it makes sense to try to keep the weight down, in that one of the major benefits of a pistol caliber carbine versus a rifle is that the latter is lighter and easier to carry to begin with, so there’s no reason to give that up if we can avoid it.

Firefield Battletek Mounted Light

Firefield BattleTek light FM9B accessory

As fellow firearm owners, we’re more than sympathetic to the fact that budget is often a concern in building a firearm and that’s especially true for the accessories. So, following from a fairly expensive light, we want to recommend something cheaper in a similar form factor. Now, you’ll be giving up a little build quality, water resistance, and a laser, but for about a third the price, this Battletek light is probably a great option for people who intended to mostly range shooting with their pistol caliber carbine and won’t put the abuse on a light that would necessitate something much more expensive. Thus, we think things like this a great FM9B accessory.

Magpul Vertical Grip

Magpul vertical grip FM9B accessory

For the next couple of items, we’re going to have to get into the legal aspects of pistol caliber carbines a little bit, so pardon the detour if all you want is accessories. But, in this case, the legal details matter a fair bit. Pistol caliber carbines can be sold as either rifles of pistols. As rifles, they are often short barreled rifles, and those are a little beside the point here. With a rifle, you can mount any kind of grip you want on the carbine and you’re just fine, no need to worry at all whatsoever.  If you have a rifle and want to do that, we think that this one, a Magpul vertical fore grip is a great way to do that.

These grips install simply into an M-Lok section and give you a solid place to hold the firearm. We like these on competition guns in particular so that you can keep down on muzzle flip and maintain more positive control of the firearm when shooting and moving at the same time.

Magpul Angled Fore Grip

Magpul angled fore grip FM9B

If, on the other hand, your pistol caliber carbine is, in fact, a pistol, you need to be a little more careful. Adding a vertical foregrip to a pistol would mean that you have now run afoul of the ATF, which is, to say the least, a potentially very long set of expensive and unpleasant days. Instead, with a pistol you are constrained to angled foregrips.

We like an angled foregrip on our pistol caliber carbines for a few reasons. First are much the same reasons as the previous grip for rifles: less muzzle flip and more positive control over the firearm when shooting quickly. Beyond that, where these really shine is in using them as a hand stop.

The great thing about pistol caliber carbines is that they’re short. The awful thing about pistol caliber carbines is that they’re short and you might put your hand over the muzzle if you’re shooting in a hurry and used to a longer rifle. Thus, having an angled foregrip as a tactile place to put your hand that is repeatable and well south of the bit where bullets come out is a great idea. This one attaches to 1913 rail sections, and is light enough to not add much bulk, making it a great FM9B accessory.

Timney Two Stage Trigger

Timney Trigger FM9B accessory

The great thing about the FM9B, and most other AR9 platforms, is that they’re built to share as many parts as possible with the AR15, or AR10 for that matter. For you, that means that you get to take advantage of the wealth of parts out there that can make your carbine an excellent competition carbine. For example, this Timney two-stage trigger meant for pistol caliber carbines.

If you have a few punches and about half an hour you can drop this trigger right into your carbine and end up with a light two stage trigger that breaks at right around two pounds of pressure after a two pound take-up. Basically, you’ll get a smooth weight of pull with a stop in the middle, which we think will allow for great control and fast follow up shots with this excellent home defense carbine. Triggers like these can make a pistol caliber carbine into a really smooth shooting platform, so we highly recommend one for your next FM9B accessory purchase.

POF Ambidextrous Charging Handle 

Charging Handle FM9B

Speaking of making the carbine a lot more shootable, some people are not necessarily content with the standard charging handles that come in most AR platform rifles. And that’s a fair critique: they only work one handed and the little lever for your finger is small enough to be an issue to get to reliably with gloves or in wet conditions. Thus, a lot of people tend to put better, larger charging handles on their AR platform pistol caliber carbines.

In this case, we’re going with a POF handle. They are labeled for .223 but, as we had mentioned before, many of the parts for the AR15 fit on the AR9 pattern as well, often including trigger parts, stocks, and, in this case, charging handles. So, this should drop in just like the stock one and will give you some major benefits. Basically, this is an ambidextrous charging handle that can be reached much more easily from either side of the gun with its larger levers. This makes it ideal for a gun you’d be shooting in less than ideal conditions, such as a competition carbine or a home defense gun, as well as making the platform more usable for left handed people who, who are often left out of the firearms market.

Sig Saur Romeo5 Red Dot Sight

Sig Sauer Red Dot Sight

To round things out, we’re recommending a red dot sight. Early in the list, we suggested some iron sights, and those are great options for most situations. With that said, red dots have some major plusses, for example being much faster on target and generally easier to use. In this case we’re recommending the Sig Romeo 5, 2 MOA dot for your FM9B. These are well made dots, as Sig cares about their reputation enough to ensure that anything with their name on it is made from quality parts and meant to last in tough conditions.  These are water resistant, take standard CR2032 batteries, and can run for 5,000 hours on one battery.

We think that these are great companion sights to a set of irons, in that they come with a mount that allows you to cowitness. Thus, if you choose to keep your irons up while your red dot is on, your sight picture still makes sense to your brain while shooting. This is especially important when shooting under stress, such as on the clock in a competition or while defending yourself. Put on one of these as your next FM9B accessory and you will be just a little bit quicker on target.

Parting Shots…

The FM9B is an excellent pistol caliber carbine, arguably one of the best made on the market today. It’s basically an AR9, but made to exacting standards. With that said, we think it is an excellent platform to accessorize into being a truly capable competition or home defense carbine. With some really simple modification, such as a set of iron sights or a red dot, you’ll be dumping Glock mags on target to your heart’s content. Of course, adding a sling and a grip will keep things handy, and a light will make it easier to shoot in a variety of conditions.

Finally, if you want to dial this great carbine in even more, a drop in trigger would be a solid idea as well. With a lot of options at several different budget ranges, you can choose what works for you to make this pistol caliber carbine truly your own. For example, you might not need a light much, so spending more on sights and picking up an affordable light might work. Or, perhaps, you know you don’t need to carry the thing around much, so you skip the sling entirely and buy a few more magazines. Whatever way you decide to customize it, the FM9B is an excellent home defense or competition pistol caliber carbine that we think you’d be more than happy to own.



Levi Frenchak has years of firearms experience between sporting and responsible concealed carry applications. Levi is a member of multiple pro-second amendment organizations including USCCA, NRA, and just as importantly, his local range. Levi is continuing a legacy of support for our rights by working with his family to increase firearms education and awareness as the lead editor of GunBacker.

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