TFB REVIEW: Flint River Armory CSA45 Carbine

    The Flint River Armory CSA45 is a side-charging carbine chambered in .45ACP that operates on a gas piston system and uses standard AR15 fire control parts. My expectations for this gun were admittedly low – another AR carbine in a caliber I don’t buy/shoot, made by a relatively unknown manufacturer is a recipe for disappointment. However, I was pleasantly surprised at how much I enjoyed shooting the CSA45. Let’s take a look.


    Aside from the design and styling, what sets the CSA45 apart from from other pistol caliber carbines on the market is that, rather than a straight blowback operation, it runs on a gas piston system. If you are unfamiliar with piston driven guns, the difference is that the gas from the deflagration of fired rounds drives a spring loaded piston into the carrier to cycle the action. In theory, rather than blasting the gas and debris particles directly into the action, a piston gun provides a smoother, cleaner shooting experience. And from my limited time with the CSA45, it functioned as designed.

    CSA45 Spec Sheet:



    As I mentioned above, I am not normally a .45ACP shooter. So I expected an inefficient, heavy recoiling rifle that offered nothing over my preferred 9mm counterparts. But, starting at the 100 yard line, I was able to consistently ring 12 inch plates under fairly rapid fire. Not only was the CSA45 a soft recoiling carbine, but both smooth functioning and very accurate.


    One benefit of the gas piston system is the lack of gas in the action that can be directed back at the shooter by blowback or direct impingement (DI) systems. This can be doubly true for suppressed guns without a gas regulation system like an adjustable gas block or carrier/key. But a look at the action of the CSA45 after 100 rounds and the bolt, carrier and other components were completely free of debris.

    Aside from the left-side charging handle, this carbine functions much like any other AR15 variant. A standard magazine release button, selector lever and classic AR trigger make for a flat learning curve. I will say that the buffer spring is a bit on the heavy side, but workable by any stature of shooter.

    Let’s take a minute to talk about what I feel are the detractors downsides of the CSA45:

    1. Although I ended up liking the styling and ergonomics of the lower receiver/receiver extension/collapsible stock setup, it is a proprietary system that doesn’t allow for aftermarket upgrades.
    2. The 25 round magazine is also proprietary to the CSA45, meaning the only place you can get magazines at the moment is from Flint River Armory.
    3. The CSA45 feels heavy for a pistol caliber carbine.
    4. Price: At nearly $1600, the CSA45 may be out of reach for some interested customers.

    Flint River Armory CSA45 – .45ACP Carbine

    The CSA45 from Flint River Armory is purpose-designed to be the most effective .45ACP personal defense weapon ever made. This pistol carbine platform is designed for: Accuracy – Strength – Reliability …and made 100% in the USA. Every pin, spring, and component of the CSA45 is made in the United States, and mostly made in the State of Alabama. We at Flint River Armory believe in the talent of the American worker. And, we believe that “Made in the USA” means something -We have pride in our product and we have an obligation to put Americans to work.

    Features, Specifications and Construction:

    • High strength, one piece buffer/lower receiver
    • One piece bolt carrier
    • Keymod forearm standard equipment
    • Tactical breakdown – no tools required
    • Includes two magazines
    • Caliber: .45 ACP
    • Operation: Short-stroke gas piston with rotating, locking bolt
    • Fire Control: Standard AR-15 type
    • Barrel: 16″
    • Weight: 6.1 Lbs
    • Magazine: High Capacity 25 round
    • Receivers: Billet machined 6061-T6 aluminum
    • Barrel: 4140 Chrome-molly
    • Bolt: 17-4 Stainless
    • Magazine: Stainless steel with black finish
    • Stock: Polymer
    • MSRP: $1595.00

    Flint River Armory CSA45 Magazines

    25 Round Magazine – 25 round magazine for use with the CSA45 Personal Defense Carbine.

    I fully expected to run into a few failures to feed/extract, but I experienced none after a few hundred rounds of full metal jacket and hollow point ammunition. Every time I pulled the trigger it went bang, extracted a round and fed a new one into the chamber until the magazine was empty.

    The CSA45’s trigger is a small step above AR15 milspec – completely usable but obviously not match grade. Remember, you can upgrade to other AR15 patterned triggers, but it’s best to check with Flint River for model compatibility specifics.

    I was really looking forward to shooting the CSA45 suppressed. Unfortunately, my review gun was an earlier model with a non-standard thread pitch. Not to worry, current versions are available with a 5/8 x 24 thread pitch, the preferred threading by the majority of U.S. silencer manufacturers.

    The CSA45 is also available as a pistol or short barreled rifle (SBR).


    The Flint River Armory CSA45 is a pleasant, clean and flat shooting carbine. It is surprisingly accurate and very fun – and this is coming from a non .45ACP shooter. That being said, I do have some concerns: it’s a bit pricey, uses proprietary magazines and the custom receiver and extension will not allow for aftermarket stocks.

    But none of those concerns have anything to do with the actual quality or operation of the carbine itself. The CSA45 is very enjoyable; if a .45 caliber pistol caliber carbine is your goal, Flint River Armory deserves your attention.

    Flint River armory

    FLINT RIVER Armory

    Many thanks to our ammo sponsor Aguila for supplying the ammunition for this review!

    Thanks to MAC Tactical for their awesome FFL services.


    Editor In Chief- TFB
    LE – Silencers – Science
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