Scary Stuff — .300 Blackout Fired in a .223 Rem Barrel
Photos and Facebook post by Tactical Rifle Shooters
Yet another .300 Blackout disaster. Unfortunately, that .300 Blackout cartridge can fit in a .223 Rem chamber. Shooting a .308-caliber bullet in .223 bore is a recipe for disaster.
The .300 AAC Blackout aka “300 BLK”, is a compact 30-caliber cartridge designed to work in AR-15 rifles. It has a shorter cartridge case to accommodate the bigger 30-caliber bullet while still fitting in a standard AR-15 magazine. Unfortunately, that’s the danger. A careless shooter can toss a .300 Blackout cartridge in with .223 Rem rounds without noting. And because the case-head size is the same as the .223 Rem (5.56×45) the rifle’s bolt assembly will happily chamber and fire the .300 BLK round. Problem is, that forces a .308 diameter bullet down an undersized .223-caliber bore. Not good!
This images were provided by Tactical Rifle Shooters on Facebook. The message was clear: “Don’t try to run 300 Blackout in your .223/5.56mm. It won’t end well. The problem is identical rifles and identical magazines but different calibers.”
For those who MUST have a .300 Blackout, here are some things you can do:
1. Use different colored magazines for .300 Blackout vs. .223 Rem.
2. Fit all your uppers with caliber-labeled ejection port covers.
3. Mark .223 Rem upper handguards with the caliber in bright paint.
4. Mark all .300 BLK Rounds with heavy black marker.
Comments by Folks Who Viewed these .300 Blackout Disaster Photos:
“The .300 Blackout is simply a badly-designed round. A properly-designed round would have had a feature in the shape that would have prevented cross loading in the first place.” — D. Santiago
“I almost made that mistake… I had a magazine of 300 BLK inserted in my .223/5.56 all night. Fortunately, I never pulled the trigger. Once I realized the mistake, I almost got ill. [After that incident] I no longer own a 300 BLK.” — B. Welch
“Happened to me hog hunting from a helo. Gun exploded in my face.” — B. Hood
“Fire-forming projectiles [is] so wrong in centerfire!” — M. Stres
“Had some dude come into the store the other day wanting .300 Blackout ammo to shoot in his 5.56 AR. It took 15 minutes of explaining for him to understand you got to have a .300 Blackout Upper!” — R. Williams
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Tags: .223 Rem, .300 Blackout, 300 BLK, AAC Blackout, AR Accident, AR Upper, AR-15, AR15, Kaboom, Safety AR
The feature that is missing could be as simple as case belt. however, that would stop 300 BLK round from chambering in a 232 chamber but would not stop 223 round from being chambered in a 300 BLK chamber. The later may lead to catastrophic results as well.
Building a 300 black out now. All my 5.56 AR’s are black, the 300 is being built in desert tan.
The reason the 300aac was created was to utilize standard ar15 bolt carriers, mags, and receivers do to unrivalled reliability; but with better terminal balistics. Just because some people cannot distinguish between a 22 bullet and a .30cal doesnt mean it is a poor design. How about loading a 380 into a 9mm magazine. Still has a bad outcome, but not a designers mistake. Keep different colored mags for your 300blk. Easy solution versus bashing a great cartridge.
There are plenty of other calibers that this could happen. Was watching a police murder show the other day the hood got a couple of 9s to shoot out of a 40. Like not pulling the trigger on a glock unless u plan on shooting it, you need to watch what u are doing.
Editor: Shooting a smaller caliber in a bigger barrel is WAY different than shooting a .308 bullet in a .223 bore.
I have 3 300blk pistols,when i go shooting i do one thing at a time if i shoot 300blk that’s all i use,i do have 5.56 223 Ar’s as well i don’t mix one at a time the 5.56 223 stays locked up ammo to,all my ammo is marked in bright letters when im finish with the 300 blk then i start on the 5.56 223 they are never on the same table at the same time.
This is exactly the reason I don’t own a 300BlackOut AR15 upper, only a bolt gun in that cartridge.
To state that 300blk is a poorly designed round is comical. It presently owns everything out to 200 yds. If you look at the history and reasoning behind its development you understand the constraints and benefits. There will always be someone inattentive enough to be a critic.
Editor: “Owns everything out to 200 yards”. Say what? Field combat to 200? NO. Group Benchrest Comps to 200? No (nobody uses the 300 BLK). Score Benchrest Comps to 200? No — that is dominated by the 30BR. PRS/Tactical to 200. No — not at all. Silhouette Comps? Again no, not at all. 3-Gun? No. Varminting? Absolutely not. Hunting? Yes you can use it, but why when a plain Jane .308 Win is better in every respect? Honestly except for very unusual uses such as subsonic suppressed at close range (suppressed) it is not a particular popular round for any discipline you can name. Anybody who says it “owns everything out to 200 yards” is deliberately trolling, or simply doesn’t know anything about the vast majority of shooting disciplines.
As for its inherent safety defects. “Because of similar chamber dimensions between the two calibers, SAAMI has listed the combination of using a 300 BLK round in a .223 chamber as unsafe.” Since the bullet of the 300 BLK is larger than the bore of the .223 caliber, chambering and firing … can cause the rifle to explode resulting in risk of injury or death. Since the mix up can easily be done, some suggest owners of firearms in both calibers carefully separate firearm and ammunition of the two types. Source: Wiki. Yes, what a wonderful round the .300 BLK is.
That’s a DOUBLE YA SHIT!
How bout a little firearm education prior to handling. You cannot fix stupid, but with a little work you can educate it. If all else fails, send stupid to a deserted island so they can only hurt themselves.
I have both. I know that you can chamber the wrong round. I am careful and DON’T DO IT! Some of these people should take up stamp collecting. I do use tan have for 300 tho.Proper procedures will eliminate this error. Always make sure your ammo matches the gun. Nothing wrong with the round.
https://www.thetruthaboutguns.com/state-your-case-9mm-vs-300-blackout/
I never understood the 300BLK. Did someone have some 221 Fireball cases left over and wondered what to do with them? It could have been a good round if the case was made longer to prevent these kind of disasters. What was wrong with the 300 Apache? (the 223 neced to 30 cal? Now called something else I believe.
The issue with the 300AAC is that the original designer of the cartridge needed to change the case dimensions so that it could not possibly chamber in a 556 NATO chamber. This is THE issue. It absolutely will fit, regardless of what you hear to the contrary. The only safety valve is that the cartridge is restricted to effectively a single powder with a very high loading density. This impedes bullet setback as the powder must be further compressed on an already compressed load. IF….IF….that bullet sets back far enough that the bolt will rotate into battery, the result will be what we have been witnessing in articles like this.
Take it from a guy that was schooled in mechanical design, worked in precision mechanism design for a dozen years and understands extremes of tolerances. The larger the NATO chamber and the smaller the 300AAC case, the greater the likelihood that a shooter will set themself up for a catastrophic failure.
Here is a novel idea, pay attention to what you are doing.
I’ve never had a problem . This sounds to me like carelessness. I know what bullet goes in my guns plain and simple !!!
Is this issue for all bullet weights or just the lighter, supersonic loads?
Noting that in the past few months I have had to remove a 308 from the firing line with a 303 round jammed in the chamber and then have a direct and unambiguous discussion with its owner about never-ever putting different rounds in the same ammo box, I am not surprised these things are happening.
Author mentioned a careless shooter could load 300 Blackout into .223 chamber. The problem is not the round. There is no room with firearms for the careless shooter. What other life threatening mistakes are made by the careless shooter. Been shooting both rounds for years, never an issue. Know your firearm!
This is part of why I’m a fan of 277 Wolverine. Larger heavier bullets than 5.56, slightly better than 300blk supersonic, though not quite as good subsonic. It’s just hurt by a current lack of market support, but it won’t cross-chamber like 300blk can. “Just pay attention!” Yes, that’s all well and good and should be done regardless, but it’s also good to minimize risks when you can.
SAAMI has published a list of ‘cross-caliber’ chamberings. One not on the list but should be is a .308 Win in a .270 Win chamber. It does fit, it does fire, it does wreck the rifle and hurt the shooter sometimes.
I can see where color coded uppers mags would be a good idea in this circumstance. There’s been enough 243s shot in 308s and 270s in 30-06s
and 30-06 shot in 7Rem Mag to know bullet diameter is not always noticed.
I’ve seen a 308 Winchester cartridge case after it was unknowingly fired in a Sako 270 Winchester rifle. The Sako rifle survived the incident.
Will someone please explain to me what the point of buying a new upper to fit on your old lower in a different caliber like the 300blk offers the shooter?
I am all for having different rifles that have different capabilities, we used them in the Army because of the capabilities it provided the squad and platoon.
This just seems like people trying to get over on the cheap. Just buy a new 300blk rifle.
It doesn’t alleviate all poosible screw ups, but it takes one part of stupid put of the equation. I just don’t get this whole cheap phenomenon of interchangeable uppers, other than getting people to screw up just for shits and giggles.
Some Scary stuff there. I’ve reloaded all my life never. Had an accident yet I’ll be 71 on this coming Monday started reloading at age 12 yrs old maybe I’m just lucky I hope not I try to always do right and have done that I’m on my phone so can’t really read this got to look on my computer but to late right but there is on one of the first two Articles I was confused about the part 30 cal bullet and the 300 I will get back to all but the first thing that comes to mind is why would u want to put that into a chamber in the first place I would have the barrel chambered to fit it in the first place not looking for a fight her just trying to understand why any one would do that To me it’s almost like dropping a 12ga round down the barrel of a 19 gage shotgun battle any way I would like to respond agen to this post after read all that’s there. Once again not trying to offend anyone just trying to get to the point of the deal just doesn’t seem right in my mind that’s not something I would do but anyway thank you for reading and I’ll get back to you guys thank you Rick.
Sounds to me like people don’t want to be responsible for their own decisions honestly. Lets blame the round or the manufacturer for our inherent failures….seems about right these days. How hard it is to keep your ammo and mags separated? Lancer and PMags exist in 300 specific mags, maybe own both and segregate that way? Lancer sells colored aluminum mag extenders, this is how I differentiate. Lots of options out there to fool proof the process, including your own eyes. Yet still there are some fools that you just can’t proof for.
Well I have just finished firing 7 rounds of .300 blackout through my ar-15 chambered in 5.56 Nato. I’ll start by saying no visible damage was noticed and no injuries occurred.
The problem was the .300 blackout was stamped. 223 rem. Obviously a shortened and reloaded batch of ammo that a local reloader sold me ‘accidentally I hope’ I get it we are human…..we do the best we can but sometimes that is just not good enough and people can get hurt or die….luckily that didn’t happen today….
I made the mistake of assuming what I had bought, loaded, and fired was what I asked for, I even slightly second guessed it when loading a mag but continued after reading the stamp…..223 ok I’m not crazy..continued on and locked in the mag and sent a round into the chamber…..the bolt didn’t fully engage so I pulled the charging handle and swiftly ejected the first round. The second round chambered up no problem and I fired the shot……went to fire another and the bolt didn’t fully engage again, yanked the charging handle, ejected the unfired round and the next round went in no problem…..fired but failed to fully chamber the next round again……so in total, 7 .300 blackout rounds were fired from two mags through my 5.56 Nato barrel….will be inspecting everything more throughly tomorrow…..thank God it ended up being an injury free mistake, only thing that’s gonna hurt is the ears of the guy who sold me the ammo…..