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).

Take your pick #csa45 #flintriverarmory #rifle #pistol

A post shared by Flint River Armory (@flintriverarmory) on


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


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

Thanks to MAC Tactical for their awesome FFL services.


LE – Science – OSINT.
On a mission to make all of my guns as quiet as possible.
Twitter: @gunboxready
Instagram: @tfb_pete


  • Brett baker

    They’re pricier than Auto-Ordnance!

  • Anonymoose

    And here I was hoping it took Thompson mags. 🙁

    • Brick

      I was just about to post the exact same thing. They look like Thompson mags.

    • nova3930

      The main design guy at FRA is an acquaintance of mine. We’ve discussed magazines a few times and there’s a lot more issues than you’d expect trying to use the available off the shelf 45 mags. I actually suggested grease gun mags and got shot down lol

      • When their competitors are running common mags like Glock mags, and they aren’t many people are going to be looking to their competitors.

        • nova3930

          ok. not sure why you’re telling me, I don’t have any control over it or skin in the game.

    • BIG problem with .45 ACP AR receivers using OTS double column magazines is the width of the magazine. Which would explain why this looks an awful lot like a Thompson magazine redesigned to be staggered, not double column.

  • TheNotoriousIUD

    Would make a sweet SBR.

    I like the stick mags.

    • Madcap_Magician

      Needs 8″ SBR. Where is the gas port hole, and how is cycling affected by cutting the barrel to various lengths? If it can run reliably at 8″, it would be kind of awesome.

  • If this were a $600-800 gun, I’d be sorely tempted. I’m just not sure it does enough over an above the other 45ACP carbines on the market to justify the expense.

    • If it were a $600-$800 gun, I’d definitely buy one. But I can accept that they won’t get their RDT&E costs back at that price point, in the numbers they can *realistically* expect to sell, even at a lower price point.

      • Valid.

      • ozzallos .

        HiPoint doesn’t seem to have that problem. Say what you want about the fugly, but the only thing that holds that carbine back is the lack of a hicap mag.

        • El Duderino

          A Hi-Point carbine that took Glock 21 mags would be a neva-been-dun-befo game changeah and sell millions.

          • ozzallos .

            Fck yes it would. the price of these unicorn carbines would drop overnight.

          • BillyOblivion

            Price is a function of “what the market will pay”.

            But availability is a function of “can I charge enough money on this to justify the time, labor and all the other hassles it takes to get this out the door”.

            If Hi-Point made their carbines such that they took Glock magazines the prices on these would go *up* because they would have to amortize the cost of development over fewer units. They would only sell to people who weren’t buying the cheapest thing on the market that was “good enough” for a day at the range.

  • CommanderRikerFacepalm

    $1,600? In this market? Guess it’s show-n-tell and not show-and-sell.

  • Paul Rain

    Excellent, not only is it in gods own pistol calibre, but it is gas-piston driven, unlike all those unreliable blowback pistol calibre carbines. Worth every cent.

  • Christian Hedegaard-Schou

    You went on about some of the pros/cons of the piston system in a pistol-caliber firearm over direct blowback, but you completely neglected to mention the single biggest advantage over blowback: Drastically less reciprocating mass = less felt recoil, less muzzle rise, less movement in general leading to a more pleasant shooting experience.

    • Person

      Maybe they are saving that tidbit for a PCC “head-to-head shootout” comparison article? Or maybe the author knows that this is a PCC offered up at $1,600 and most people are going to buy a TNW, PSA, or (gasp) Hi-Point carbine, a bucket of mags, and a case or two of ammo with money left over for a fresh pair of sneakers.

      • Christian Hedegaard-Schou

        Some of us work for a living and $1600 isn’t that big of a deal for quality firearms.

        I sometimes wonder if all the people following this blog work for McDonalds with the way they go on about the price of literally everything.

        • Person

          You’re right, “$1,600 isn’t that big of a deal for quality firearms.”

        • Just Say’n

          I make just under $100k/yr and I’d never consider a $1600 “range toy” like this. I’d get a Kel-Tec at 1/4 the price first.

          And what’s with the text on the lower receiver? It’s like the default font from MasterCAM. For $1600/ea they could hire a designer to come up with some cool logo instead….

          • Christian Hedegaard-Schou

            Neat. And I would never consider a garbage Kel-Tec.

            It’s almost like we all like different things.

          • John L.

            Kel-Tec doesn’t make anything in .45acp, so … no you wouldn’t.

        • I can afford a $1600 rifle that trips my fancy hard enough. The idea of a PCC merely tickles it — which is why this particular gun is priced outside my range.

          After all, if I wanted a practical variation of the same thing, I’d do a Blackout carbine with heavy subsonics, that yields the same MV as .45ACP in roughly the same weight, but with much better bullets, and the ability to use supersonics for more range. So this is *to me*, merely a range toy my daughter might appreciate — but that’s not a $1600 line item in my mental budget.

        • Douglas Pickerell

          Or maybe some people have a wife that would divorce us over a 1600 rifle

          • Christian Hedegaard-Schou

            Get better wives?

          • Upgrading wives is WAY more expensive than $1600 rifles. LOL

        • Beju

          IMO, the issue is that a $1600 .45 ACP PCC is inherently going to appeal to a narrow market. People tend to associate PCCs with cheap plinking, and .45 ACP is priced similarly to .233/5.56. This likely accounts for the choices in the .45 ACP PCC being limited to cheapies like Hi-Points, Beretta CX4s (which doesn’t seem to be produced in .45 anymore), and blowback ARs, then a couple other $1000+ options (CMMG MKG45 and KRISS Vector).

          Even accounting for people who aren’t going to spend $1600 on any firearms, the people that can/will spend that much or more have a lot of choices in this buyer’s market. It buys a pretty nice AR pattern rifle, or if you want to be different, a Tavor. It gets you a SIG MPX pistol, or an MPX rifle for slightly more.

    • Pete – TFB Writer

      You’re right, I did skip over why this gun was so easy shooting. The reduced mass makes this gun what it is – actually pleasant to shoot. Having had (past tense emphasis) a blow-back .40S&W PCC, I can definitely appreciate a gas piston driven gun.

    • Madcap_Magician

      I was extremely surprised by the increase in felt recoil the first time I shot a 9mm Colt carbine. The blowback operation really does increase felt recoil dramatically. It obviously wasn’t unpleasant or anything, but it was harder to shoot than the 5.56 x 45 mm equivalent.

      • Christian Hedegaard-Schou

        Yeah it’s not unpleasant, it’s just…. Really thumpy? More than you would expect being a 9mm. And it’s not because 9mm has an exceptional amount of energy or anything, but you have that super heavy bolt and buffer moving back and forth, and that’s just a lot of mass to get moving. Shakes the gun all over the place, making follow-up shots difficult.

        Anyone who’s shot an MP5 or Sig MPX will immediately notice a huge difference.

        • Madcap_Magician

          I have not shot an MP5 or MPX, but ‘thumpy’ is a great way to describe the Colt 9mm carbine. Not heavy recoil, but yeah… thumpy coming and going.

  • Keiichi

    So, in a $1600 package you don’t get the benefits of common mag compatibility or AR parts compatibility.

    Not seeing the upside here… would have been nice if they’d actually done something innovative for the PCC market…

    • Christian Hedegaard-Schou

      They did do something innovative. It’s gas piston which drastically reduces the amount of reciprocating mass needed, making this gun shoot far more pleasantly than any other PCC, I can pretty much guarantee.

      But everyone is so wallet-sensitive on this blog that they are blind to it.

      • Keiichi

        I’ll grant you the internal mechanism, but I’m talking about the overall package.

        The AR platform is not an efficient or appropriate design for a pistol cartridge based rifle since the magazine could feed through the grip, like a pistol. Innovative would have been a rifle weighing a pound less, using their piston system, with a more sleek and compact design.

        As to being wallet-sensitive: Everyone have different priorities; for most, $1600 is quite a lot for a range toy. I spent that much on my long range competition rifle. A novel mechanism isn’t enough to justify the cost when cheaper, but just as reliable and durable, options are available, unless I suppose one was so recoil sensitive that a blowback rifle was intolerable…

      • Hardwood83

        We get it, you have lots of discretionary income. So do others, but being able to afford something and it being worth the cost are not the same.

        I like this package, but it is not worth $1600 to me. I have several other guns that cost more than that, but this one isn’t worth that much to me. Cost =/= value. I’m sure you know this, but you’ve commented several times about how poor everyone must be, so I felt compelled to spell it out.

      • Not blind. It’s a good feature. But there’s already the low recoil Kriss Vector. And the recoil on 45acp carbines at a much lower price point isn’t exactly punishing.

        It’s not that it’s not potentially good. I’m just not sure it does enough, over and above existing options, for people to form a line.

  • maddog

    shouldn’t it be “25 round standard capacity” magazine. for $1600 you would think they would give you a decent pistol grip, not one that usually gets thrown away.

    • Christian Hedegaard-Schou

      I’m glad they don’t include a fancy pistol grip. I like the Ergo’s, if it came with a MIAD or MOE from Magpul I’d still end up swapping it out. Other people really like the Tango Downs.

      Which fancy grip should it come with? Because it’s not going to please everyone. Best they include the cheapest throwaway grip possible and let everyone upgrade it to the one THEY prefer.

      • Keiichi

        For $1600 I shouldn’t have to provide my own grip, at my expense. It should come with a grip appropriate for its design, not a throwaway grip. As is, it’s now a $1600 + ~$30+ rifle, thus further accentuating the excessive price point.

        … oh, and keep your “wallet-sensitive” crap. The value of a thing must justify the cost in the context of its competitors to be worth the expense. This, not so much.

  • If it was in 10mm or some other caliber that was at least interesting/had a right to exist, and the price wasn’t quite so outrageous I’d strongly consider it.

    But 16 hundred dollarydoos for a PCC in Fuddy-five? Pfffft ahahahahahahah

    • nova3930

      At one point they were gonna make a 10mm but I’m not sure what happened with it…

      • Jared Vynn

        Would it take glock mags? Have to ask it’s traditional.

        • nova3930

          no idea.

  • Dr. Longfellow Buchenrad

    What are the pros and cons of a pistol caliber AR against a full size AR15 in .300blk [or any other regular caliber; .300blk specifically mentioned only because its the most comparable caliber common in AR15s]

    I have a hard time seeing the usefulness of a pistol caliber AR, but Im willing to be enlightened.

    • Beju

      Compared to .300BLK, PCCs offer cheap plinking. Cheap brass cased 9mm is ~1/3rd as much as cheap .300BLK, and .45 is ~1/2 as much. Go with imported steel case 9mm, and it’s ~1/4th as much.

      Now comparing .45 ACP to .223/5.56, cost doesn’t make sense given the existence of cheap .223 that costs less than cheap .45 ACP. I could it see making some sense if one wants to shoot steel targets at closer ranges, or relatively cheap subsonic shooting for suppressor use.

    • Keiichi

      Frankly, I agree, but not in opposition to the PCC concept – just in opposition to the use of the AR pattern for the PCC concept.

      A lighter, more compact platform that feeds mags through the grip a la a pistol, which shares mags and caliber appropriately, would be a far more attractive proposition, in my opinion.

      • Dr. Longfellow Buchenrad

        I agree. Im not saying I dont see a use for PCCs. I just think the AR pattern is not the most optimized for it.

        Im not one to make a big deal about magazine compatibility or even caliber commonality though.

  • noob

    So yes to “can i put a binary trigger in it?”
    But no to “can i change the receiver extension and stock?”

  • George Smythson

    I have a similar rifle from Bazooka Bros that uses modified grease gun mags; it’s a pleasure to shoot and has been quite reliable. It uses all standard AR mil-spec parts so it can be updated just like any other AR (I built mine from a stripped lower)… I would choose it over the FRA rifle shown here.

  • RogUinta

    Proprietary mags = fail

  • Madcap_Magician

    What’s the deal with the proprietary stock? Is there a mechanical or design requirement served by that?

  • tsh77769

    Proprietary mags = deal breaker. Double stack single feed only makes it worse. Price is like WTF?

  • Keith

    I don’t think “detractors” means what you think it means!

    • Pete – TFB Writer

      “To reduce the value, importance, or quality of something.”

      • RocketScientist

        Yeah buddy, that’s the definition for DETRACT… not detractORS. the word you used, “detractors”, is defined as PEOPLE who disparage someone or something. A good synonym would be “critics”.

        So as you typed it you basically said “Let’s take a minute to talk about the critics of the CSA45:” followed by a list not of people who do not like the gun (which would make sense), but instead by a list of faults of the gun (which makes no sense).

        Here’s a hint I used to give my students. Never use a word you don;t use regularly or that you need to look up. Odds are you’ll use it wrong and come off looking like an idiot.

        • Pete – TFB Writer

          Jokes on you, I usually look like an idiot anyway…

          Edited (credit Keith and Rocketscientist)

        • Person

          That’s cool. I used to tell my students to not insult their audience because it closes their ears.

          (This was back before the birth of the internet comment section. Now the three sides of the rhetorical pyramid are 1. trollos, 2. insultos, and 3. the ol’ standby, pathos. And if you can drop a meme in there…Ooh, son!)

          • RocketScientist

            Wait, you’re criticizing my teaching style, and you believe people can close their ears? What an idiot.

          • Person

            …And here’s your diploma.

  • TheUnspoken

    The review gun looks rough around the edges, hopefully the full production guns are a little more polished.

    I would prefer more of a sub gun look over AR, if it isn’t going to be AR parts compatible anyway. “Manual of arms” and all but this one is side charging, only the mag release, grip, and safety selector, and trigger are AR. Bolt hold open appears to have lost its head.

  • Bucho4Prez

    If you are going to use proprietary mags, at least make them double feed.

    • Width of the lower receiver. true double column .45 mags are FAT. Remember that 5.56x45mm cases are basically the WIDTH of 9x19mm.

  • gunsandrockets

    With a locked breech action, should be adaptable to .45 Super and .460 Rowland versions.

  • CA

    It just seems like one of those rifles that don’t fit any particular need or niche. You have to do something that really stands out, and not something that just reduces recoil.


    Can you run 45 super or 450 SMC in these?

  • int19h

    Finally, some PCC designer remembered about M1 Carbine, and why it was a good idea.

    *looks at the price*

    Oh, never mind.

  • civilianaf

    First off, thanks to Flint River Armory for doing something different for a change. Second, thats the gun that CMMG ripped off for their operating system. CMMG also ripped off the BHO from another company, but thats another story.

    • Vitor Roma

      The CMMG is a delayed blowback, so it isn’t a rip off, just a different way of reducing the mass of the BCG.

  • Mr Lizard

    Can someone please just make a 10mm AR that uses Glock mags, and a mag well designed for them?