Starting in the mid-1980s, semi-automatic pistol-caliber carbines became quite popular, particularly in law enforcement circles. While Colt AR-15s were available, most law enforcement agencies didn’t purchase them for street use, because the plethora of expanding ammunition available today for the 5.56mm/.223 cartridges did not exist then. Because of that, there was a great fear of over-penetration on soft targets by police administrators of that era. The pistol-caliber carbine was seen as a great alternative, especially since there was a wide variety of soft-point and hollow-point ammo available for the 9mm pistol round.
Colt was at the forefront, offering a blowback 9mm submachine gun based on the M16, as well as a 9mm semi-automatic carbine. But there were other options available as well. Marlin made a fine little 9mm blowback carbine — later available in .45 ACP — known as the Camp Carbine. The 9mm version used Smith & Wesson pistol magazines, while the .45 used Colt mags. They were handy guns, easy to use, inexpensive, reliable and accurate, and they found their way into police cruisers of the time (even though they were designed as camp and farm firearms, not law enforcement weapons). Marlin stopped making them in the wake of the assault weapons hysteria that culminated in the Assault Weapons Ban of 1994.
Ruger joined in with a similar blowback carbine produced from 1996-2006 and designed for law enforcement and civilian use: the 9mm PC9 and the .40-caliber PC4. Both used Ruger pistol magazines.
The Ruger carbines eventually fell out of favor with the development of modern hi-tech expanding 5.56/.223 ammo and the sudden popularity of the AR-15 rifle produced by new manufacturers when the 1994 Assault Weapon Ban sunsetted in 2004.
Pistol-caliber carbines of any type all but disappeared from the commercial market until recently, when people began to rediscover the fact that pistol rounds produce less noise and blast than do 5.56s from an AR-15. One of the best new pistol-caliber carbines I have seen is the new Flint River Armory CSA45.
Chambered in .45 ACP, the Flint River CSA45 represents a major departure from traditional pistol carbine designs. Instead of blowback operation, the CSA45 is piston operated!
In talking with the folks at Flint River, I found they decided to go with a short gas piston system of operation primarily to keep the action cleaner than is possible with blowback operation or direct gas impingement. I found that their pistol system works very well.
The CSA45 is all USA-made, with most of it being made in Flint River’s home state of Alabama. The CSA45 is basically a 16-inch-barreled M4 carbine (pistol and SBR versions are also available). The upper and lower receivers are billet-machined 6061-T6 aluminum. The threaded barrel is 4140 chrome moly steel, while the bolt is 17-4 stainless steel. The round Keymod fore end runs nearly the full length of the barrel, and both the fore end and the flattop upper receiver feature full-length Picatinny railing. Unloaded weight is a feathery 6.1 pounds.
These are the basic features of the CSA45. Now let’s get into the features that make it a standout arm.
As I said earlier, the CSA45 is gas piston operated. However, it dispenses with the military AR-15 charging system that operates the reciprocating bolt. The charge handle (which also serves as the forward assist) is on the left side, which allows right-handed shooters to keep their full shooting position intact while reloading. There is no bolt release button, so dropping a locked-back bolt requires pulling back the charging handle fully to the rear, then releasing. However, the bolt can be locked back by pushing down on the lower portion of what would be the bolt release while holding the charging handle to the rear.
While the charging handle setup varies from the standard AR setup, the safety and magazine release are standard AR. The same is true of the trigger group, which can accept any aftermarket drop-in system from any manufacturer.
The polymer adjustable stock gives the CSA45 a bit of the appearance of the FN SCAR or similar rifles. It works well, but is the only point of complaint I have with this rifle — it could use a bit of rubber padding. Even with a mild cartridge like the .45 ACP, I felt some discomfort against my shoulder while firing repeatedly from the prone position. I didn’t notice discomfort while firing from a standing position.
Magazine capacity is 25 rounds. The magazine (two are included with purchased guns) loads easily. While the design is adapted from the Thompson magazine, the two are not interchangeable, making the CSA45 mag entirely proprietary.
I had two different optics to test with the CSA45. While there are no sights included on the commercial gun, Flint River included a Tactical Prismatic Reflex Sight with laser sight attachment from Scorpion Outdoor Products (www.scorpionoutdoors.com). This sight, which has an MSRP of $149.95, features a heads-up reticle display that can be changed to red or green by the single-selection lever with varying degrees of brightness. It also allows the user to select from 4 different reticles. Mounting hardware is included.
The Scorpion sight is a good choice for this type of close-range CQB carbine. No additional riser was needed to obtain proper eye position.
The second sight I had to work with was an updated Generation 3 version of the Lucid HD7 Red Dot Sight (www.mylucidgear.com). These improvements include capped turrets, a new reticle set with more capabilities for the operator and the availability of a Flash Filter accessory. The HD7 was the sight I actually used for my test-firing. MSRP is $249.
I replaced the Scorpion reflex sight with the HD7 before heading to the range. I had four different .45 ACP loads with which to test the CSA45: Precision Delta 230-grain FMJ, Winchester White Box 230-grain FMJ, SIG Elite Performance 230-grain FMJ and SIG Elite V-Crown 230-grain JHP. I wanted four different loads to see how the .45 ACP fared when fired from a longer-than-pistol-length barrel.
While the 9mm picks up an increase in velocity from a carbine-length barrel, the lower-pressure/lower-velocity .45 ACP does not benefit much — if at all — from being fired from a carbine. A .45 Carbine does benefit the shooter in that most people can shoot a .45 from a carbine much more accurately at extended range than they can from a pistol.
The Flint River Armory CSA45 proved to be drop-dead reliable. No hitches or bobbles, no opening night jitters. The piston system works very well for this caliber! It is also very smooth, as it utilizes a lighter bolt than can be used in a blowback carbine.
Charging was easy using the left-hand cocking handle. The trigger was a bit crisper than standard military grade. The magazine ejected and inserted easily.
Recoil was similar to a 5.56mm rifle, with much less blast. While a flash suppressor or muzzle brake could be attached to the threaded muzzle, it’s not necessary — unless you want to increase the “cool” factor. There simply isn’t enough pressure exiting the muzzle during firing to make it necessary.
Running the ammo across my chronograph verified my previous understanding of the ballistics of the .45 ACP when fired from a carbine-length barrel.
| Ammo Type | Factory Ballistics for Pistols | Chronographed Carbine Ballistics |
| Precision Delta 230-grain FMJ | N/A | 783 feet per second |
| Winchester 230-grain FMJ | 910 feet per second | 908 feet per second |
| SIG Elite Performance 230-grain FMJ | 850 feet per second | 877 feet per second |
| SIG Elite Performance 200-grain V-Crown | 918 feet per second | 1019 feet per second |
The CSA45 was more than accurate enough within its intended range of 150 yards or so. The Lucid HD7 produced a very bright picture with an easily visible and simple reticle. It is built tank-tough and was easy to dial in and line up perfectly regardless of shooting position. It is hard to beat, especially for the price, and the capped turrets are really a welcome addition. Unfortunately, I forgot to bring along my Bog Pod shooting rest. This required me to improvise my prone shooting position. Even so, I was able to easily obtain groups in the 3- to 4-inch range once I dialed in the Lucid HD7. Had I remembered the Bog Pod, my groups would have been much tighter.
The CSA45 ups the ante for pistol-caliber carbines. Its light weight and handy size make it a great perimeter rifle for smaller properties or camping excursions. Its appearance is great, and its profile with magazine inserted is reminiscent of the Thompson Submachine Gun. It is currently on sale for $1595.
More info at: www.flintriverarmory.com
