Gun Review: The Flint River Armory CSA45 Carbine

Flint River Armory CSA45 carbine stock — The sliding stock rides over the aluminum receiver.

Flint River Armory CSA45 carbine rail — The upper is railed so you can easily add optics like a Holosun reflex sight.

Flint River Armory CSA45 carbine magazines — The CSA45’s proprietary 25-round magazines taper to a single-stack presentation for reliable feeding but remain easy to load.

Flint River Armory CSA45 carbine handguard — The KeyMod handguard provides plenty of space for accessories, and its length makes it easy to get a far-forward grip on the carbine.

Flint River Armory CSA45 carbine muzzle — The muzzle comes threaded for sound suppressors, and a knurled thread protector is included.

Flint River Armory CSA45 carbine controls

Flint River Armory CSA45 carbine magazine closeup

Flint River Armory CSA45 carbine aiming angle

Personal defense is the single greatest impetus behind new firearm purchases in America. America’s moral compass spins faster than a Mississippi Delta ceiling fan, and the media reminds us daily, typically in the most gruesome of terms, of the innate sinfulness of man. In the face of ever-worsening threats to our homes and our families, Americans are exercising their constitutional rights to self-defense in ever-greater numbers.

In 2015, we Americans bought just shy of 20 million new firearms. That’s about 55,000 for every single day of the year. While Americans are indeed visiting their local firearms emporia in record numbers seeking firearms with which to secure home and hearth, I would assert that, by and large, we are actually doing the whole thing wrong.

The handgun is and always has been the hardest of all firearms in common use to master. What are at once a pistol’s major strengths turn out also to be its most compelling weaknesses. A handgun’s small size necessitates power limitations and miniaturized controls. Additionally, shoot long enough and you will inevitably see somebody’s stubby little muzzle inadvertently wander around to point at something soft, fragile and innocent.

The answer to this conundrum is the pistol-caliber submachine gun. Most European police agencies discovered long ago that the combination of pistol cartridges and a carbine chassis provides the best balance of control, reliability and effectiveness for a defensive firearm. Alas, the prejudices of the unenlightened conspire to keep these superb little weapons out of the hands of most American civilian shooters. However, Flint River Armory now produces a truly nifty smoke pole that offers all of that subgun chic, power and safety in a package that transfers without undue governmental interference.

All For The .45

The .22 LR is a hoot to shoot, but I once saw a poor unfortunate man in an urban ER who took sixteen .22 rounds to the lower extremities during a drug deal gone almost comically wrong. His opposite number escaped to peddle his illicit pharmaceuticals elsewhere, but we presumed him to have been armed with a Ruger 10/22 or similar equipped with an extended magazine. Our luckless miscreant actually survived to continue making the world a better place upon his ultimate discharge from the hospital. The point being, if you want to be taken seriously in an armed encounter, then you’d better bring a serious gun.

The .45 ACP cartridge was the product of the veritable wellspring of firearms awesomeness that resided within the peerless mind of John Moses Browning. The story is by now well known, but old John Moses thought up the .45 ACP as a counter to the Philippine Moro tribesmen, themselves some of the first radical Islamic terrorists the U.S. military had the displeasure of meeting in combat. Against this enemy in the early 20th century, the old .38 revolvers of the day, throwing simple round-nose bullets, were found to be terribly wanting.

Browning assessed the 115-grain 9mm bullet that our European friends were just beginning to field and, in typical American fashion, simply doubled it. The subsequent 230-grain .45 ACP round soon earned a reputation as a proven stopper. Nowadays, as those thumb-sized cartridges typically push high-tech expanding bullets, their downrange effectiveness is literally unprecedented.

Flint’s Take

The good folks at Flint River Armory set out with the goal of developing the most effective personal-defense weapon (PDW) ever made. The CSA45 is designed and built entirely in America by Americans, and is indeed a remarkable piece of work. Built around monolithic 6061-T6 aluminum receivers, the CSA45 weighs a mere 6.56 pounds unloaded with a 16-inch barrel. The gun runs from a locked-breech, short-stroke-piston-driven action and feeds from a proprietary 25-round, stainless steel magazine. The company also offers a sexy short-barreled rifle (SBR) version with a 10-inch tube. The gun is available in a variety of colors thanks to the miracle of Cerakote.

The collapsible stock telescopes over the receiver for a perfect inline distribution of recoil, and there is plenty of railed real estate for anything you wish to mount. The controls will be familiar to anyone who has ever hefted an AR. The charging handle reciprocates with the bolt on the left side, and the required cocking force is trivial.

While all of that boilerplate comes straight off the Flint River Armory website, what is not so easily captured is the originality and unfiltered coolness of this gun. You can’t swing a dead cat without hitting somebody who is putting together AR rifles in his or her basement and declaring them to be God’s gift to the armed American. What Flint River Armory has done, however, is design and build something truly new, innovative and effective.

How Does It Run?

In a single word—wow. Chances are you have never shot anything like this. The .45 ACP pistol cartridge thumps hard downrange while remaining utterly tamed by the piston-driven, gas-operated action. The gun lacks the penetrating snap of a high-velocity rifle and spits those big fat slugs out with monotonous reliability. The top-quality 25-round magazine will keep you in action long after the threat has grown non-threatening.

Doubles and triples are easy, even on the move, and the chassis maneuvers like a Jack Russell terrier on speed. The lower parts kit is standard AR, so the trigger feels like an old friend. With some quality tactical glass atop the upper receiver, the CSA45 utterly dominates indoors. I topped the receiver with a Holosun optic and built up the ultimate home-defense weapon, just like the Flint River guys said I could. The same rig as an SBR would be all the more extraordinary.

I tried five different loads through the CSA45 and printed five jagged holes at 20 meters off of a simple rest. The CSA45 is clearly an optimized close-combat tool. However, this sweet-shooting gun will drop your rounds right where you want them out to the limits of the cartridge.

There were two stoppages in the first magazine, but after that it ran flawlessly. The bolt locks to the rear when the gun is empty. Give the charging handle a go and the bolt runs forward. The double-stack magazine tapers to a single-stack at presentation, but I still got it loaded easily without a tool.

There is no conceivable circumstance wherein anyone might make a legitimate self-defense shot at more than about 20 meters, but that didn’t stop me from loading up a magazine or three and trying my hand at some serious ranges. Out to 200 meters and beyond, the CSA45 becomes more mortar than carbine, but the exercise is simply great fun. It really is tough to describe how smooth this gun is in action. I’ve never shot anything quite like it.

True First Responder

Whether the CSA45 sits in the back of your closet, behind the seat of your pickup truck, in the trunk of your squad car or in a bag in the minivan during the cross-country trek to grandma’s, literally nothing you can buy in America without a tax stamp will perform better for defensive applications. The CSA45 clearly isn’t a pistol, but it kind of isn’t a rifle, either. This gun is a carbine in the purest sense and is literally perfect for home defense.

When you hear the glass breaking downstairs or get swarmed by rioters run amok on the freeway is not the time to be pondering your self-defense solutions. With a little forethought and practice, the prepared American can legitimately inoculate themselves against highwaymen, burglars and similar unpleasantness. A Flint River Armory CSA45, along with a couple of spare magazines, brings peace of mind not to be found in a conventional handgun or smartphone.

With negligible exceptions, cops are hardworking, dedicated public servants who armor up every day putting their lives on the line to help keep us safe. However, if life really goes sideways, what they are really best at is catching the guy who killed you. For those critical first few minutes when you face the threat alone, a single Flint River Armory CSA45 in the hand is infinitely better than a dozen police officers on the phone.

A 9mm version of the CSA carbine is currently in the works, and pistol variants are available as well. However, the .45 ACP offers proven downrange performance, controllable penetration and reliable functioning, all in a compact and maneuverable platform. A .45 ACP Glock 21 is an indisputably fine handgun, but the CSA45 is hugely easier to learn and run safely. For female shooters, kids first learning the art or old geezers like me with callouses on their trigger fingers, the CSA45 is a fresh solution to the thorny question of personal protection. With the CSA45, Flint River Armory really did build a better mousetrap.