Rock River Arms KABOOM

RifleShooter had his Rock River Arms AR-15 go kaboom when he was shooting Ultramax remanufactured ammunition. RRA blamed the ammunition and replaced it at cost …

The bolt carrier appears to have split, you will notice it protruding into the magazine well. On the left side the upper was cracked and bulged, the bolt hold open sheared off. On the right, the upper bulged and the ejection port cover bent. The magazine was blown out of the rifle. Notice the how the bottom of the mag bulged from the pressure.

Thank fully no one was hurt. I think that is a testament to the design of the rifle and the quality of RRA.

According to the owner, RRA told him it was cased by the ammunition (Ultramax) and this is the second gun they had destroyed by it. The RRA mishap report, “Lower OK, bolt still in battery, lockup. Fired casing came apart at base, no bulges in barrel.” RRA replaced the upper at cost ($323.50) after he signed a release absolving them of any liability. They suggested contacting the ammunition manufacturer.

The moral of the story is you should not be surprised if your gun goes kaboom shooting remanufactured ammunition.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Darkness

    That’s considerably little damage to the AR, RR got some high quality construction to their rifles. Still, if you pay that much for a gun people, do yourself a favor and take care of it- remanufactured stuff is crap, stick to factory ammunition. Way less kaboomage happens with factory then remanufactured.

  • Darkness

    That’s a good rifle, sustaining that little damage. Still, if you’re gonna spend that much on an AR, do yourself a favor people and take care of it. Remanufactured is crap, stick to factory ammunition. Way less kaboomage happens with factory then remanufactured

  • Cymond

    On one hand, it seems like we always hear about the evils of reloaded ammunition, and ‘remanufactured’ is just a term for ‘reloaded by a business’.

    On the other hand, does it really make THAT much of a difference if the brass has been used once before? If company ‘XYZ’ can manufacture safe ‘factory new’ ammo, then why can’t ‘XYZ’ make safe ‘remanufactured’ ammo? Maybe we should blame ‘XYZ’ instead of remanufacturing?

    • Reverend Clint

      ive bought re-manufactured ammo before… never had an issue. Im always supect of places that have “Ultra” or “Max” in the name so a combo is a no go.

    • Geodkyt

      Well, what you have to ask yourself is:

      “How does XYZ obtain their brass, and how do they know it’s only been used once, twice, or has some of it been resized and reloaded by Cletus on his rock-cruncher so many times you can nearly read newsprint through it?”

      “How do they sort their brass? Are they loading only once-fired brass from ammo loaded to a consistant case spec and pressure (like, they only use once-fired M855/M193 brass from US Army ranges), or do they take ANY old 5.56/.223Rem case that arrives in a bucket. (Even single-use cases but mixed manufacturers can result in inconsistant cases.)”

  • gir6543

    I would love to see a large scale study done on reloaded ammo. Obviously I would never shoot 308 caliber or larger reloaded because of the scary kaboom pictures. Still I would bet that the amount of money saved using reloads. I would be willing to guess that the actual risk of kaboom is far outweighed by the cost saved from cheaper ammo.

    obviously one cannot put a price on safety, which is why i am only questioning small calibers

    Maybe i’m incorrect, If there has been a study of any kind please post 🙂

    • D

      It’s actually quite possible to put a cost on safety, on a per round basis.

      Figure out the rough percentage of catastrophic failures (say, 1 per 10,000 rounds of reloaded ammo).

      Figure out the percentages of catastrophic failures that cause injury (50%).

      Figure out the percentage of injuries that are serious enough to cost money to fix (say, 75%). Average out a cost – say, 500$ per injury (some would be a few bucks, some would be thousands, so average might be 500).

      Do the math out: .0001 * .5 * .75 * 500

      or more easily: 0.0000375 * 500 – so about 2 cents would be the cost of safety per round, with the assumptions we’ve got.

      Feel free to tweak the values (especially the average injury cost), though, to get something you feel is more reasonable.

      • W

        D, excellent post!

        if saving a few bucks on reloaded ammo (that statistically has more of a potential to render your 1-2000 dollar rifle as scrap and fuck your hand or eyesight up) is more important than your personal safety, then that is your business.

        Personally, there is NO cost for my eyesight or full dexterity of my hands.

        Reloading works fine if you have some super rare wildcat or H&H discontinued cartridge of some type.

        For 9mm, 223, and 308, ill stick with factory ammunition.

    • Geodkyt

      Actually, I would concern myself with prioritizing by peak pressure, not round size. A larger caliber, larger capacity rounbd at a lower peak pressure is less likely to suffer a catastrophic failure than a smaller, but higher pressure, round — even if the “bigger” round has more total energy.

      Timing issues will also affect failures — although it apparantly had NOTHING to do with this particular failure (bolt was fully locked at failure, which eliminates timing as a suspect).

    • jdun1911

      KB! will happen if you shoot a lot. Doesn’t matter what firearms or ammo. It just statics. Don’t lose any sleep over it.

      As long as you have eye protection you should be fine.

      Injuries are rare with handgun calibers KB!.

      As long as you do not put your hand around the magwell or use a bullpup rifle your injury will be minimum on anything less then a .50 caliber. Sure there are cases where people lost a finger or two but those are the exceptions.

      • W

        i have never seen a kaboom with factory ammunition.

        Im not saying that it doesnt happen, im just saying after the hundreds of thousands of rounds of factory ammunition i have witnessed and fired myself from scores of different firearms and ammunition manufacturers, there were no kabooms.

        now with reloads, that is a entirely different issue.

        The risk of me fucking up during reloading is enough of a deterrent to make me stick with factory ammunition when firing common calibers.

        If I had a H&H or some other discontinued or wildcat cartridge (which I dont), i guess I would reload out of necessity. Other than that, its simply not happening.

  • Chase

    Replacing the upper at cost seems like a nice thing for Rock River Arms to do.

  • Tinkerer

    Let’s see:
    -Direct-Impingement AR-15? Check.
    -Gas tube that is shorter than the original AR-15 rifle-lenght gas tube? Check.
    -Bolt carrier that splits? Check.

    We’ve seen this kind of catastrophic failure before. Not a broken bolt, or bolt lugs, or case failure. It’s the bolt carrier -the one that is being pumped full with hot and high-pressure gases- the one that fails.

    • Tyler Marcoz

      I’m unsure if you’re trying to imply that DI is somehow bad, or the like? But given its clearly an ammunition issue, rather than the weapon itself, not sure what you’re going for.

      • Don

        The above post from Tinkerer shows a complete lack of understanding of how the AR gas system works. High pressure, high temperature gas is not pumped into the BCG. After dumping heat & pressure passing through the gas port, entering the small expansion chamber in the gas port, traveling down the gas tube and entering yet another expansion chamber, the gases are nowhere near the pressure, temperature of BTUs it had while shoving the bullet down the bore. A shooter can fire off enough ammo to get the gas block hot enough to burn skin, yet can hold the BCG in hand and barely feel any warmth. I know this for a fact because I tested it for myself

      • Geodkyt

        Let me think about that, Tinkerer. . . i’ll put on my failure analyst hat (it’s nicely broken in after nearly two decades of regular wear)

        Yeah, gas pressure/temperatures high enough to cause fairly thick tool steel that has multiple gas escape paths to blow up, yet the really thinwalled gas tube itself didn’t split open and spill the gas before it reached the BCG.

        Riiiiiight. . .

    • Tinkerer

      I have no problem with the thumbs downs and the explanations given. It comes with free expression. But the photos are plain for all to see. The bolt head didn’t fail, the bolt lugs didn’t fail, the chamber didn’t fail. What failed was the bolt carrier. And it’s not the first destroyed AR-15 bolt carrier I have seen to fail that way. But I have yet to see a non-AR-15 bolt carrier to experience this failure. Have you?

      • Sigivald

        The bolt head didn’t fail, the bolt lugs didn’t fail, the chamber didn’t fail. What failed was the bolt carrier. And it’s not the first destroyed AR-15 bolt carrier I have seen to fail that way.


        But the explanation you gave (“It’s the bolt carrier -the one that is being pumped full with hot and high-pressure gases- the one that fails.“) for why that’s so doesn’t make any sense.

        After all, as mentioned, if it was “hot and high-pressure gases”, how does that thin little gas tube take it?

        Those pictures there show me the bottom of the BCG failing, presumably from overpressure from a case separation; if it was through the gas system, with, as described, the bolt still in lockup, I’d expect the gas key to have failed, not the bottom of the BCG.

        The gas key takes all the pressure and heat of the gas in normal operation; the bottom of the BCG doesn’t get jack all from that.

        What does put a lot of pressure in it, enough to make it go “boom”, is a case separation (“Fired casing came apart at base”).

      • Tyler Marcoz

        What I hear is “I have been proven wrong, but refuse to admit it.” I’ll be honest, I don’t have an encyclopedic knowledge of gun failures. But I’ve seen enough evidence to know that the AR15 is not the first weapon to have a catastrophic failure from bad ammunition.

    • Nmate

      It should also be noted that operating gas pressure is a combination of gas port size, gas system length, and barrel length. For instance a 14.5″ mid-length gun with a relatively small gas port (I’m not sure of the exact size) is going to have lower pressure than a 20″ rifle system.

      You’d have to talk to someone who knows more about ARs than I do for specifics, I’m sure someone over at M4carbine would be able to expand upon this. The point is, just because the barrel/gas system are shorter than the original design does not necessarily mean it has more gas pressure. The whole point of the mid-length was due to the fact that 16″ carbine barrels were over gassed.

  • Nicks87

    Ultramax is junk.

    It’s the only ammo that has ever malfunctioned in my piston AR. Even the cheap steel stuff runs better.

  • Brice

    I think I’d send a bill to Ultramax, same as I would to Federal if I had a gun came apart on their ammo. Don’t magically think that the owner of the machine that fills the cases up is going to mean they never have an overcharge or an out of spec case. I know I’ve seen a recall notice from one of the big boys this year on their .223 ammo.

  • alannon

    Seems to me that it wouldn’t be hard, or expensive, to get a machine that when given known-weight cases can automatically accept or reject based on weight.

    Assuming they use automated machinery, and not a bunch of guys sitting at loading benches. I’ve never looked into how the (re)loading industry works.

    • D

      That would lower the bottom line, and they are very likely all about making the most profit for the least expense possible.

    • Greg B

      It’s not that simple, variation in case/bullet weight make a simple weight the complete round solution non-feasible.

    • Aaron

      The issue with this is if the manufacturer screws up and uses the wrong powder. IIRC, rifle powder in a pistol case can cause under-pressure, but pistol powder in a rifle case can cause massive over-pressure.

      If you use the wrong powder but the same charge weight an automatic scale won’t pick up the mistake because grains are a unit of weight.

  • Michael

    Wow, this hits home for me. The first AR I bought was a RRA Midlength rifle. The first ammo I ran through it was 500 rounds of Ultramax.

    Thankfully, I didn’t have any problems, but I’ll make sure I never buy that ammo again.

    I will admit that is one of the least damaged AR’s I’ve seen after sustaining a KB.

  • Esh325

    I bet the pictures will be posted on Internet forums out of context, and it will be proclaimed by the Internet warriors that Rock River rifles are prone to blowing up then.

    • bmrtoyo

      ohh nooo im gonna give my rock river away ,,not

  • Michael

    I have not had any problems with ultramax in my ARs, but as their 55grn soft points shoots excellent in my Savage I don’t feed my ARs with it anymore.
    Have there been any problems with Wolf ammo in ARs?

    • Griffin

      Wolf jams my M&P 15 VTAC like nobody’s business. It seems to happen at least once every 100 rounds. The case gets firmly stuck in the chamber after firing and the extractor just rips through it. I can’t remove it without using a cleaning rode tapping it out from the front.

      Doesn’t matter how much I clean the chamber and no other ammo has ever had a problem.

      It sucks because I have at least 800 rounds of .223 wolf that are of no use to me.

      • Geodkyt

        I’ll take that “useless” Wolf ammo off your hands. I won’t charge a disposal fee, and I’ll even pay shipping! {Chuckle}

    • Geodkyt

      This has been tested. Firing ANY steel cased ammo can give you problems when you switch back to brass cased stuff.

      Why? Metallugy

      Steel doesn’t stretch and fully form to the chamber as well as brass does. (Which is a god thing, as steel that does stretch doesn’t go quite back to original shape as well as brass, so primary extraction would be a bear! {grin})

      So, firing steelcased stuff leaves more crap (powder fouling, just like the crap that turns your patches black, basically) in the chamber. When you switch to brass casings (especially US civilian brass), the stretchier brass form fits to the cruddy chamber, and the extraction is like it was lubed with little rocks.

      Yup – that crap in your chamber after shooting steel cased ammo is not lacquer, it’s just regular fouling, only WAY more than you’re used to seeing from Winchester Party Packs (Winchester White Box Value Pack).

    • W

      the only problems i have heard of is in ARs with heavier buffer springs. steel cased ammo typical of wolf doesn’t obturate as much brass does, so there is typically less energy being exerted when the bolt carrier group recoils back. Sometimes there is Failure to Feed issues and if the rounds to cycle adequately, they dont push the bolt back far enough to lock the bolt to the rear when the magazine is expended.

      The inferior obturation compared to brass (brass expands more than steel when heated in a firearm) also is the reason why these cartridges shoot dirtier. There is more carbon and residue that escapes into the chamber and internal parts every time a round is fired.

      In all practicality, with most ARs out there, steel cased ammunition like tulammo or wolf causes NO issues. in fact, i shoot thousands of rounds of wolf and tulammo through my carbines every year and have no problems (besides being dirtier i guess).

  • jdun1911

    People needs to be aware that KB will happen in whatever gun and ammo. It is not the question of if it happen but when. It will happen because of statistics. The more you shoot the more chances that you will be rewarded with a KB.

    I had my fair share of KB over the years. My last KB happen a couple of months ago on my AR15 using .22lr conversion kit. It was an OOB KB! using Winchester X ammo. Thirty minutes before that, one of the club members told me he had a KD!. His EAA Witness KB because of a squid round. Frame undamaged but slide and barrel totaled.

    With that said the vast majority of gun owners will never experience a KB! because at most they go to the range once a year and shoot less then 100 rounds. For the very very small minority that shoot 10k or more each year, KB! will happen in their lifetime. It pretty much guarantee.

    • schizuki

      “In the first test, the [Browning] fired 20,000 rounds without incident. The reliability was exceptional, so Browning fired another 20,000 rounds through the weapon without any parts failing. The Ordnance Board was impressed but was unconvinced that the same level of performance could be achieved in a production model. Consequently, Browning used a second gun that not only duplicated the original trial, but it also fired continuously for 48 minutes and 12 seconds (over 21,000 rounds).”

      81,000 or more rounds without a kaboom. Guess they made ammo better back then.

      • jdun1911

        Don’t argue with me. I used to shoot a lot. I know a lot of people that shoot a lot. I’m not talking about a thousand or two each year. I’m talking 40k or more.

        It is a statistical fact that if you shoot a lot you will experience KB! Is not if is when.

        The truth is KB! is more common then people would like to admit. People that have the same experience as I have will have the same conclusion.

        • ArgonBuster

          Maybe it’s the ammo you’re shooting or sloppy gunsmithing. I’ve been shooting for 33 years – in the army, my backyard, and numerous gun ranges. I’ve fired a stupid number of rounds during my lifetime. I don’t want to think about how rich I would be if I could get my money back for all the ammo I’ve been through and I agree with Griffin and schizuki. I’ve never seen or experienced a kaboom first hand. So, according to you, just because it hasn’t happened in 33 years doesn’t mean that I’m safe, statistically it WILL happen to me one of these days? My dad drove for 60+ years and NEVER got into a traffic accident, not even a minor bump… although STATISTICALLY he should have at least once right? I’ve been driving for 25 years and I’ve never been a in a wreck either. Jdun1911, I get where you’re coming from – maybe if it were to happen to me, I would be scared silly and try to warn people about potential kabooms, but fear-mongering and shallow arguments aren’t the way to educate people. Oh, and for those wondering – I don’t shoot remanufactured ammo or any reloads – even once fired brass. I WILL shoot my own handloads. Just like I pack my own chutes… and I will never own a Glock or a RRA.

      • Chase

        “Don’t argue with me,” jdun1911? This is the Internet!

        • bmrtoyo


    • schizuki

      I’m going to somewhat retract that. In fairness, you did say, “in their lifetime.”

      • schizuki

        OK, just for the “don’t argue with me”, I fully retract my partial retraction. Neener!

    • Griffin

      Where are these stats you’re referring to? Or are you basing this on anecdotal personal experience?

      First, nothing happens “because of statistics”.

      Second, if its anecdotal then you don’t have the data to make a valid statistical analysis.

      Third, is this your first time on the Internet? “Don’t argue with me” is not an effective debate response in real life; on the Internet it’s just silly.

      Fourth, I think you are confusing the concepts of possibility with likelihood. It is possible for any gun to have a kaboom with any ammo; just like its possible that I can die falling out of bed but that doesn’t make it likely. It’s true that if I were to live to 200 it would be more likely I could die falling out of bed but statistically it is still very unlikely.

    • Glockenspiel

      I used to shoot more than I do now. But between what I have shot, and what the shooters at my range have fired in my presence over the years, I’m estimating I’ve been present for about 3 million rounds downrange. Not a single gun has kaboomed. I must be lucky.

  • Lance

    Steve quit blowing peoples rifles up for fun!!! LOL!!!!

  • Shootin’ Buddy

    Any use of the forward assist by the shooter?

  • Dayum, that looks like it would have been scary to live through..

  • gunslinger

    always itnerested to see a failure analysis of KBs.

  • Brandon

    That’s the second time Ultramax ammo has gone kaboom in one of his guns? Fool me once, shame on me, fool me twice…

    • Griffin

      I’m pretty sure RRA was saying this is the second gun made by them that had this issue. Not the individual owner that experienced the kaboom.

  • jdun1911

    There are two things people needs to know about the AR15 and 5.56 in regard to KB!.

    1. It is impossible to double charge .223/5.56. It barely able to fit a moderate load in the casing.
    2. It is almost impossible for the AR15 to go out of battery. You have a better chance of winning the lottery or getting hit by 10 lighting bolts in a row.

    It could be a squid round or wrong powder in the case.

  • Not so much a case head separation venting into the bolt carrier and down through the magazine well as much as a case failure, usually directly underneath the extractor, venting through the firing pin hole.

  • B

    Note to self: Do not feed my RRAs Ultramax ammo. I like my RRAs.

  • Cuban Pete

    Note to self: Avoid remanufactured stuff.

  • DJM

    This was obviously caused by crap ammo but RRA is also a crap gun. Off topic, but any gun that uses a commercial spec receiver extension and has a name like “Elite Operater Tactical Zombie SWAT XXXTreme Edition” is not quality and actually piss poor quality. Nevermind the barrel, BCG, MPI/HPT testing, feedramps, etc!!! Anyone who thinks RRA, DPMS, Bushmaster, Stag, Windham, Olympic, etc makes a quality gun knows nothing about the AR15/M4 family of weapons — sad, but oh so true.

    • Griffin

      The name impacts quality eh? How about color?

      • bmrtoyo

        or day of the week and weather

    • Geodkyt

      Honestly, there’s darned little difference in the stock rifles from almost ALL manufacturers. The one place where there is a truly significant parts quality delta between most major manufacturers in their base rifles is the barrel. Even places where there is a qualitative difference (like bolts), frankly, 99% of shooters will NEVER find out, because the difference is more a matter of durability, not reliability – and they’ll never fire the ten thousand rounds or more to wear out the cheap parts. Likewise, they aren’t generally firing the fully automatic strings or high per session round counts that would expose substandard parts.

      Now, there is often a difference in workmanship in ASSEMBLY.

      Why is this so?

      A. Given the barrel extension layout of the AR system, the barrel is the truly critical componant for accuracy.

      B. Things like M4 feedramps are really designed for reliability for carbines in AUTOMATIC modes, and are fairly vestigal on semis. (Disclaimer – I prefer the reliability mods intended for automatic use, just in case there could possibility of an incremental reduction in failures. It’s a rabbit’s foot, and I don’t pretend otherwise.)

      C. Do you realize how FEW parts manufacturers there are? Most “manufacturers” are assembling the majority of the rifle from parts made by the same jobbers supplying their competitors.

    • W

      the only difference between “commercial-grade” ARs and “mil-spec” ones is the composition of the bolt and carrier group’s steel.

      A overwhelming majority of parts are very similar. A few companies that are premium-grade cost what they do for a reason: they dont just use stock parts.

      Its a bit off subject, but i would love to own a industry that sold the same product and type to different competitors.

      • Geodkyt

        It happens in more industries than you think. {grin}

      • W

        I think most industries in retail do, though not to the same degree as AR parts 😀

        yes it happens quite often. Business is about a system of sale, not necessarily the “best” product.

      • Aaron

        There is quite a bit more to a mass produced high profit AR than just the composition of the bolt and carrier steel. Tolerances in the machining of the rough forgings also play a role. A company the pays 125.00 for their lower is going to have better tolerances than a company that pays 75.00.

        The commercial buffer tube may be produced at a lower price point, again due to the shape and looser tolerances.

        Staking at the gas keys and the castle nut to keep fasteners locked into place.

  • ct dealer

    DO NOT BUY FROM Rock Rivver Arms!! they no longer care about their customers and would rather pump out inferior products rather then what was promised when ordering. Ordered a LAR-15 Operator 2 with chrome lined barrel and chrome bolt carrier promised within 90 days. six months later I finaly recieved rifle with no chrome bolt carrier. told the delay was due to not having the sites and then the barrels. contacted customer “service” when recieved and was told too bad we posted it on our web site and said price/product subject to change. No notification to me or attempts to rectify solution other then “send it back and wait until carriers come in.” Worst firearms service ever! buyers/dealers beware!!

  • Brad Stafford

    Look up colt you’ll find the same problems with every ar brand I love it when people bash a brand

  • Aaron

    I’ve got a few issues with previous comments, but to keep it short:

    Rifle functioned as it was supposed to by venting the excess energy out the magazine well while keeping the bolt locked into the extension. So the design is good.

    Heavily over-pressure ammunition will KB! any firearm. Doesn’t matter if it is an AK, FN-FAL, SCAR, or a G3. When pressure overwhelms the maximum survivable pressure of a firearm design KB! happens.

    Hand-loading is far different from many re-manufacturing setups. Hand-loaders by majority shoot what they load so they take the necessary diligence to make sure the powder type and charge are correct. They do so to search for the perfect balance of functionality, performance in both exterior and terminal ballistics, and accuracy.

    Quality of remanufacturers also come into play, I believe that any of you would shoot Black Hills Remanufactured and have no concerns.