F4 Defense – AR Rifle and Part Manufacturer

F4 Defense

F4 Defense is a name we’ve heard repeatedly from builders and AR enthusiasts when it comes to higher-end rifles and parts.  Not being overly familiar with the company, I reached out to the F4 Defense COO, Dave Fairfax, to discuss the company and how it is attempting to stand out in the crowded AR marketplace.

Q:  Dave, thanks for sitting down with us.  Can you start us out with a bit of background on F4 Defense.

A:  F4 Defense…We’re a company made up of veterans and engineers who happen to love guns.  We’ve been big proponents of the AR-15 for years.  Several years ago we tinkered around with the idea of starting a company and we kicked it down the road until we could figure a way to come in and do it a little different.  We ended up partnering with a brilliant engineer who is our Chief Small Weapons Designer and it took off from there.

F4 Defense

Right now, consumers have so many choices.  When we started, we asked ourselves “what can we do that is a bit different?” And, that’s difficult with the AR-15, considering how much competition is out there and the number of different ideas and designs. We wanted both a design and a look that really stands out, which is tough in this crowd. There are so many great companies out there.

F4 Defense Adaptive Rail System

So, one of the early things F4 Defense hung our hat on was the adaptive rail system where we took both Picatinny and M-LOK and incorporated into the rail.  No more adapter rails…you can attach right to the rail with either MLOK or Picatinny.   And we did it by integrating it into a normal rail profile…no more bulky quad rails. We patented this a few years ago.

F4 Defense
F4 Defense Adaptive Rail System

While that’s not an Earth-shattering invention, it’s something different, which is tough in this market.  We never had the intention of making $600 ARs.  There’s nothing wrong with that, of course, but we wanted to do something on the higher end.  The idea being it’s for someone that’s going to buy a gun and not change anything. People sometimes purchase a gun that they have all these changes in mind, and that’s great, but we were trying to go the opposite direction.  We realize our customer base was going to be smaller, but it was something that we wanted to do.  A rifle from F4 Defense is going to be a kick-ass rifle right from the beginning…a high performer and it looks damn good.

Q:  Dave, F4 Defense has a lower that is not only visually striking but is very well built and thought out.  Can you talk a bit about that?

A: Everything comes down to the baseline of reliability and accuracy.  We didn’t want to go completely radical with the lower receiver. We wanted it to make sense.  We machined out enough relief cuts in there to keep the weight down.  We knew we wanted ambi controls. The lower is very easy to run with the ambi bolt catch and ambi mag release.  Ergonomically, it’s a comfortable lower and it looks good.

F4 Defense
F4-15 AMBI Matched Billet Receiver Set with rail…CNC machined from Aluminum Billet 7075-T6

As far as the mag well…You see it on race guns with pistols…flared mag wells on Glocks and things like that.  Opening it up allows consistent and fast reloads.  When you are doing billet, you have options like that. 

Q:  I love buying complete guns if I know it’s a solid company.  That said, AR builds are a passion, and its great to see F4 Defense offer a builder’s set.  How did that come about?

F4 Defense
F4-15 AMBI Builder Set

A:  We have the complete rifle crowd that wants a turn-key solution.  And, that will always be offered.  If a person wants a reliable and accurate complete rifle that’s ready to perform, we have that…no question.  But, there are so many builders out there. We wanted to make sure we address them with our builder sets.  We saw companies out there offering the builder sets and “We have the parts anyway, so why not offer them?” was the simple thought process there.

Q:  One thing you’re offering that really stands out is your small-frame AR-10.  F4 Defense has managed to pull off a .308 AR-10 at 6.5 lbs., which is very impressive.  Can you talk about how that came about?

F4 Defense SF-10
F4 Defense Small Frame AR-10, the SF-10…weighs 6.49 lbs…not including scope and suppressor.

A:  We have a massive portfolio of designs, but it’s difficult to figure out what to come out with next. The AR-15 is a no-brainer because its mil-spec and the market is there, but we’ve definitely been pushing our small-frame .308 platform, which is a 6.49 pound .308.  It really sits right in between an AR-10 and an AR-15. It;s built around the DPMS Gen2 pattern.

We saw a big push with AR-15s to go lighter and smaller, and we figured “why not with the AR-10 platform?” We always said “I don’t want a 12-pound rifle with optics.  Or a 10-pound rifle with optics.”  So, what can we do?  Let’s go smaller and lighter. But we didn’t want to do that with a skeletonized receiver or use titanium parts or things like that. We wanted to make the platform itself smaller.  So, we worked with Remington to get a licensing agreement and built our rifles based on the Gen 2 design.  It took quite some time to get the legal stuff straight, a few years, but we are there now.  You see, so many companies step all over patents and other companies’ IP… we refuse to go down that road, and that’s why it’s taken so long to get this released. But we’re there now.

f4 Defense
Left to Right: AR15 / F4 Small Frame AR10 / AR10 Much more compact and lighter.

With respect to design, it’s an AR-15 from the mag well back.  We shrunk down the bolt carrier group, which was extremely important.  You didn’t need this massive BCG.

We had a goal to keep it under 7.5 pounds.  We didn’t know we could go as low as 6.5, and we did that without sacrificing balance. One of the questions we always get is that it must have a lot of recoil.  But it doesn’t because the bolt carrier is smaller, moving less mass. The bolt face is the same, it’s just a reduced size.  It’s not low mass, nor are there any crazy relief cuts to make it lightweight. You have less mass moving and we use a hydraulic buffer which really softens it up.  It’s a super smooth shooting rifle.

F4 Defense

F4 Defense Small-Frame for Precision Rifle Shooting

Also, we’ve seen that precision shooting has exploded in the last few years.  We wanted to step into that market which is one we love and understand.  To do that, we wanted to make something that is compact, lightweight, reliable, and something that was dead-nuts accurate.  We wanted a super accurate, reliable and good-looking gun…and our small-frame AR-10 was the result.

F4 Defense
Small-Frame SF-10 in .308

F4 Defense Small Frame for Law Enforcement

Another main factor behind F4 Defense’s small frame AR-10 was our push into law enforcement. Being veterans, we are huge backers of the military and law enforcement.  The fact is, you’re not going to have an officer with a 22” 6.5 Creedmoor.  They are in urban environments and they don’t take long shots…it’s just the nature of the job.  So, what would they look for in a rifle?   Their snipers want to go with a heavier caliber.  A lot of them have AR-10s, but they have 18”, 20” AR-10s that are weighing 11, 12, 13 pounds.  It only makes sense to offer a 6.5-pound rifle with a 16” barrel that’s more compact so you can get in and out of vehicles and move dynamically with a much lighter and compact rifle, without sacrificing stopping power.

Variety of Calibers

F4 Defense

When it comes to caliber, we’re doing everything from 7mm-08 Remington to 8.6 Creedmoor, .243 Winchester, 6 Creedmoor, .260 Remington, 6.5Creedmoor, and .308…and we’re trying to offer as many choices that make sense with that .308 bolt.  This really opens it up to hunters, competitors, law enforcement, and across the board.

Our goal as an AR-15/ AR-10 company is to give as many people as many options as we can with calibers and that goes back to trying to do something different.  In my blog recently, I wrote that it’s nothing new to do all these calibers, but we’re the first company to do it all in a small frame. We’re so excited to get out there and get behind all these calibers and serve as many people we can in the marketplace.

Q:  Dave, you’re around enough firearms that we’re curious, what does your ideal build look like…something for a training class or perhaps home defense?

A: For a home defense weapon, I am a huge proponent of the AR platform.  Especially now with the pistol braces, you can go short without paying that 200 dollar tax stamp.  It’s a great platform for home defense.

As far as how I would put one together, I would start with a high-quality barrel, bolt, and trigger and pair with a quality mil-spec receiver set and a quality rail.  I’m a “less is more” guy for a home defense weapon…just  a reliable, well made short-barreled rifle with a red dot and flashlight.  I run a suppressor with all my personal weapons and cannot recommend it enough, especially in a home defense situation.  .556 suppressed still cracks with supersonic ammo but its much better than the alternative in a confined space.  It sucks, but pay the tax and get it done!

Barrel and Trigger

Then you have to look at what is going to make this firearm a good shooter… and that is your barrel and your trigger.  A quality bolt is important but the barrel is the heart.  This is why we dump so much money into our guns getting the best barrels in there we can.

F4 Defense
F4 Rifle equipped with a Trijocon MRO…


With optics, specifically magnified optics…Nightforce.  Cannot say that enough.  There are others out there that make fantastic products but Nightforce is hard to beat. If you’re going with non-magnified optics, the Trijicon MRO  or the Aimpoint T2 are top notch.


Tremendous thanks to F4 Defense COO, Dave Fairfax for taking the time to speak with us about his company.  Should you want to learn more about other companies out there offering up quality ARs and accessories, drop us a message and we’ll reach out so we can get more information on them for you.

Did you find this article useful?

Let the author know with a 5 star rating!

Average rating 4.8 / 5. Vote count: 4

No votes so far! Your rating will help us continue to provide valuable and interesting content.

Since you found this post useful...

Follow us on social for first dibs on brand new content!

We are sorry that this post was not useful for you!

Let us improve this post!

Tell us how we can improve this post?

Notify of

Inline Feedbacks
View all comments

If you want to be among the first to know when we release new content, your best bet is to sign up via email:

We’ll keep the emails to a minimum and we will never sell or give your information to a third party.

Would love your thoughts, please comment.x