.300 Blackout in 5.56 rifle?


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Edarnold
January 23, 2014, 10:57 PM
A quote from an AR manufacturer rep claimed the military was backing off from the .300 Blackout because of instances of troops firing the cartridge in 5.56 rifles. Is this possible? Anybody have a sample round to try chambering it? Please DON't try firing it!

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griff383
January 23, 2014, 11:01 PM
It wont even chamber, the bullet diameter of a 5.56 is .224 where as a 300 blackout is .308. Do a quick search to find a side by side comparison and you will clearly see what Im talking about

rcmodel
January 23, 2014, 11:02 PM
No, it is not possible.

You can't stuff. a .308" bulleted cartridge in a .224" barrel or chamber.

rc

R.W.Dale
January 23, 2014, 11:32 PM
You guys are giving very incorrect safety related advice based on the ASSUMPTION that .30 caliber bullet hanging onto the end of a. 300 blk case WON'T be driven into the case by the forward momentum of the bolt when it slams into the far end of a 223 chamber

http://www.thefirearmblog.com/blog/2013/12/18/300blk-fired-5-56-fs2000/

http://bearingarms.com/300-blackout-in-a-223-wylde-ar-15-kaboom/

http://www.ar15.com/archive/topic.html?b=3&f=121&t=612049

Edarnold
January 24, 2014, 02:45 AM
Mr. Dale, thank you for the confirmation on this condition. Given how short the Blackout case is compared with the original 5.56, it seemed plausible that it could chamber. In these cases, it did, with catastrophic results. I never thought much of the Blackout concept except for use in a suppressed weapon, I suspect after a few more incidents like this we will see a lot of used Blackout uppers and reloading components for sale.

chris in va
January 24, 2014, 05:06 AM
Doesn't it also fit into a standard 5.56 magazine? I know a 7.62x39 fits just fine.

R.W.Dale
January 24, 2014, 07:10 AM
Doesn't it also fit into a standard 5.56 magazine? I know a 7.62x39 fits just fine.


Yes. It uses everything the exact same as 5.56 except for the barrel

cfullgraf
January 24, 2014, 07:35 AM
I did not think a 300 BLK could chamber in a 223 Remington chamber but bullet set back makes sense.

This is not a unique event in the shooting world but maybe a bit more publicized due to the popularity of the rifle and the ammunition involved.

I have several AR-15s chambered in various other cartridges that use the standard 223 Remington/5.56 NATO bolts and I have a concern of chambering the wrong ammunition. I take care to not get ammunition mixed up but mistakes happen without the proper care.

Be careful out there.

68wj
January 24, 2014, 07:43 AM
It wont even chamber, the bullet diameter of a 5.56 is .224 where as a 300 blackout is .308. Do a quick search to find a side by side comparison and you will clearly see what Im talking about
The chambering issue is more about overall dimentions than bullet diameter. True, a 30 cal bullet won't fit down the bore, but the 300 BO's case is shortened to 35mm and puts the bullet's ogive close to the 5.56 chamber's shoulder. Add a little setback and you get a chambered round with a well plugged front exit.

crazysccrmd
January 24, 2014, 09:46 AM
A quote from an AR manufacturer rep claimed the military was backing off from the .300 Blackout because of instances of troops firing the cartridge in 5.56 rifles.

What manufacturer said that? I haven't heard or seen anything about the military even considering 300blk.

carbine85
January 24, 2014, 10:04 AM
Quote:
A quote from an AR manufacturer rep claimed the military was backing off from the .300 Blackout because of instances of troops firing the cartridge in 5.56 rifles.
What manufacturer said that? I haven't heard or seen anything about the military even considering 300blk
This^^

It sounds like you have to have at least 2 mistakes before this can happen. This isn't stopping me from building a 300 B/O

68wj
January 24, 2014, 10:05 AM
What manufacturer said that? I haven't heard or seen anything about the military even considering 300blk.
Doubtful for general issue, but special uses. It was LWRCI that said it in an interview about their new 6.8 SPC rifles, saying that the military was looking at the 6.8 again.

Tirod
January 24, 2014, 11:40 AM
I don't know why the military would have to look at 6.8 again, they did, had weapons in theater, and were the "founding fathers" of the cartridge anyway. SF and AMU did all the ground work. But, you never can tell what DEVGRU is up to, and they have their own special budgets.

The potential conflict of loading the wrong ammo is a major issue with an Army, tho. It affected the adoption of 6.8 in a foreign country, the standard mag well spec created the conflict - is the soldier loading 5.56 or 6.8? The mags look and fit the same.

Since the developer of the six8 made the magwell different and had Magpul make the legendary polymer mag in 6.8 for it - not standard spec M16 sized - it became part of the decision to adopt it. You can't stuff the new mag in a spec magwell, and a 5.56 mag is so loose you figure it out quickly.

The .300BO however, is interchangeable, which is a fail. Armies don't want that. It's why it won't be adopted, among many other reasons, such as having already been out for over 30 years. It's far from a new idea.

If somebody has a shooting task and the .300BO fills the sweet spot, sure, barrel it up. Like other alternate calibers tho, that ballistic envelope and it's practical application sometimes get overlooked in the rush to share in the hype of ownership. THAT will be the reason we see barrels on the market - it just didn't really do what the buyer expected. What he should have done is look into it's actual results more, not let his emotions tell him.

There are plenty of other potential rounds that can cross load into guns they don't belong in, a shooter at the range should keep his ammo distinctly marked so that the wrong combinations don't happen. That should be common sense, but it's something we all have to learn, sometimes for the second or third time.

Robert101
January 24, 2014, 12:16 PM
Seems like a case cannelure at the base of the bullet might be a viable solution to stop enough bullet setback and keep the breech from closing. I mean, if the 300 BO is that important a round it seems a simple solution can be found to the multi-loading problem.

R.W.Dale
January 24, 2014, 12:49 PM
Seems like a case cannelure at the base of the bullet might be a viable solution to stop enough bullet setback and keep the breech from closing. I mean, if the 300 BO is that important a round it seems a simple solution can be found to the multi-loading problem.



No cannelure could be relied on to prevent something like this. On further research supposedly no setback is needed with some shorter OAL supersonic loads

M1key
January 24, 2014, 01:59 PM
Great thread! Certainly dispels a common assumption many folks might have....

SC

Mike1234567
January 24, 2014, 02:10 PM
Ignorance can only stop one from doing... it can't stop one from trying.

ATLDave
January 24, 2014, 02:15 PM
What R.W. Dale said. If you've ever seen a .300 BLK case, you can easily understand how this could happen and with devastating consequences.

Of course, 20 gauge shotgun shells will fall right down into a 12 gauge chamber, then blow the gun to smithereens when the next 12 fires into a completely obstructed bore. Doesn't mean it's not perfectly OK to have both 12's and 20's. But probably not both on the field in your hands at the same time!

ATLDave
January 24, 2014, 02:29 PM
If somebody has a shooting task and the .300BO fills the sweet spot, sure, barrel it up. Like other alternate calibers tho, that ballistic envelope and it's practical application sometimes get overlooked in the rush to share in the hype of ownership. THAT will be the reason we see barrels on the market - it just didn't really do what the buyer expected. What he should have done is look into it's actual results more, not let his emotions tell him.

I agree with this. Either you load it supersonic, in which case it's not as good as the other AR-length cartridges, or you load it subsonic, in which case it's basically a projectile with the weight of a .45ACP, but not the diameter. Other than suppressed use, I'm not sold on the idea that it is really all that useful.

griff383
January 24, 2014, 06:52 PM
The chambering issue is more about overall dimentions than bullet diameter. True, a 30 cal bullet won't fit down the bore, but the 300 BO's case is shortened to 35mm and puts the bullet's ogive close to the 5.56 chamber's shoulder. Add a little setback and you get a chambered round with a well plugged front exit.
I would have bet a paycheck on a 300blk not chambering in a 5.56 chamber, didnt really think about setback. Glad it was cleared up for the OP and I apologize for offering bad information.

Bartholomew Roberts
January 25, 2014, 01:27 AM
As RWDale said, .300 can chamber in 5.56 rifles on occasion and the consequences are not good. Having said that, even among the Spec Ops guys, use of .300 has to be extremely rare. So given the level of expertise of the few guys who would have leeway to use .300 and the relative lack of use even by those guys, I'm skeptical it is a big problem for the military. Sounds more like something a marketing guy for LWRC dreamed up... or I'd guess LWRC since Remington is the parent conpany behind 6.8 and .300 and makes money either way.

holdencm9
January 25, 2014, 12:23 PM
I learn something new everyday. I guess I knew that .300 Blackout was shortened but didn't think it would be so short that the bullet can fit within the shoulder region of the .223 chamber.

I guess I better avoid .300 Blackout in favor of .458 SOCOM for my next build! :D

cfullgraf
January 25, 2014, 12:40 PM
Doubtful for general issue, but special uses. It was LWRCI that said it in an interview about their new 6.8 SPC rifles, saying that the military was looking at the 6.8 again.

I am not saying the 300 BLK cannot be stuffed and fired in a 223 Remington chamber but manufacturers are known to bad mouth or exaggerate something just in an effort to win a lucrative military contract.

68wj
January 25, 2014, 01:52 PM
I am not saying the 300 BLK cannot be stuffed and fired in a 223 Remington chamber but manufacturers are known to bad mouth or exaggerate something just in an effort to win a lucrative military contract.
Sure have and will. In this case, accusing the customer of something they didn't do to sell something doesn't seem smart, unless it is true.

mokin
January 25, 2014, 02:06 PM
Thanks for posting. I learned something today! And, on a Saturday no less. I can now log out and go on with my day.

I really did not think such a thing would be possible. Good to know.

hentown
January 25, 2014, 05:24 PM
What manufacturer said that? I haven't heard or seen anything about the military even considering 300blk.

I'm a manufacturer. .300 Blackout is being used by some units of the U.S. military. There, now you've seen it or heard it. :evil:

jmorris
January 25, 2014, 08:26 PM
There are people that can ruin an anvil with a rubber mallet.

It is the same reason we have to have labels on coffee cups that say "hot" and lighters that have warnings not to use "around heat or flame".

Some just need protection from themselves.

SuedePflow
January 25, 2014, 09:26 PM
Interesting topic. I'm a fan of .223 and .300aac, but I've never considered how this mistake could happen. Just for curiosity's sake, I just fit a factory .300aac round in my .223 case gauge and I was very surprised at how far it will fit in.

Barnes Vor-tx 110gr in a Dillon .223 case gauge. It is .113" away from flushing up. I could definitely see how one could get set-back enough to close the bolt.

http://i68.photobucket.com/albums/i17/paulvolk/Shooting/20140125_211213_zps321809d5.jpg

oldpapps
January 26, 2014, 08:06 AM
"AR manufacturer rep claimed the military was backing off from the .300 Blackout because of instances of troops firing the cartridge in 5.56 rifles. Is this possible? Anybody have a sample round to try chambering it? Please DON't try firing it!"

Can't respond to hear-say from an un-named rep from an un-named manufacturer. I don't see it plausible for the military going to the .300, but what do I know?

However, after I put together (I like the way people say they 'built' when all we do is put parts together) my .300 AAC Blackout, I stuck a round in a mag, the mag in a .223/5.56 chambered AR and dropped the bolt. Irritated me to no end. The bolt wouldn't go into full battery, no lock up, won't fire. OK, that's good. But, just the bolt drop jamb so severely, I had to drive the round out from the muzzle. Ruined my sample with the bullet type. (Don't get excited, the case was fully prepped with out punching the old primer and replacing it and no powder. Just a sample for that bullet profile and seating depth.) And if you are wondering, I try it the other way to. The .223/5.56 round is too long and the bolt didn't get close to lock up. But it didn't jamb or tear up my sample.

Could a .300 be fired in at .223/5.56 chamber? Yes, with the proper (or is that improper) series of screw ups. The bullet would have to set back, a lot. A lot of chambering force would be required, more than a reasonable person would exert. Inattentive loading/selection of magazines would be a must.

So yes, anything can happen with a big enough hammer.

One things is sure, I'm not going to try that again, total PIA to clear.

hentown
January 26, 2014, 08:56 AM
I don't see it plausible for the military going to the .300, but what do I know?


Don't know what you know, in general, but I do know that, per my previous post, some units of the U.S. military are using .300 Blackout, generally for subsonic use out to 150 meters.

Walkalong
January 26, 2014, 10:08 AM
Will the subsonic 300 BLK rounds with heavy bullets go in a .223 chamber? Surely they are loaded as long as spec allows. I haven't tried any yet myself.

Walkalong
January 26, 2014, 10:28 AM
Here is a 125 Gr SST loaded to crimp ito cannelure, and a 147 Gr FMJ loaded to crimp into cannelure. I just tried them in a Wilson .223 gauge. I wish I still had a couple of other bullet styles loaded. The 125 Gr TNT might go all the way in.

http://www.thehighroad.org/attachment.php?attachmentid=194063&d=1390682452
http://www.thehighroad.org/attachment.php?attachmentid=171314&stc=1&d=1347118938
http://www.thehighroad.org/attachment.php?attachmentid=194098&stc=1&d=1390750276
http://www.thehighroad.org/attachment.php?attachmentid=194099&stc=1&d=1390750276

hentown
January 26, 2014, 11:00 AM
I think I'll just make a point of not firing any of my .300 Blackout ammo in any of my 5.56 rifles. ;)

SuedePflow
January 26, 2014, 12:02 PM
(I like the way people say they 'built' when all we do is put parts together)

Well....

build
verb
1.
construct by putting parts or material together over a period of time.

Walkalong
January 26, 2014, 12:42 PM
giggle snort...... :)

But yea, it's almost as easy as Legos, almost.

wally
January 26, 2014, 02:02 PM
I like the way people say they 'built' when all we do is put parts together

Its not "people" its the BATFE that defines this as "manufacturing" -- changing a stock on a Saiga is "manufacturing" a non-922(r) compliant rifle, or adding a stock to a pistol is "manufacturing" a Short Barreled Rifle.

oldpapps
January 27, 2014, 02:13 PM
I'm too picky, I guess.
I've never built a car. But I have changed tires, fuel pumps, water pumps, one carburetor (do they still make them?), rings and pistons. But I've still not built a car. Must be the way I think, all confused.

I still don't consider it likely that 'Uncle' will ever switch over to the .300 AAC Blackout. Again, my way of thinking, as a general issue item. This doesn't remove most anything from some special operations need some place down the line. I wouldn't think of a M1A as being the normal 'COPs' weapon. But I carried one on a special assignment.

I don't know 'nutin'. Just ask my oldest grand daughter. She's at that age...

Scojen
January 27, 2014, 07:31 PM
Hi all,
New guy here, 300 black out fills the bill in some regards, good hog round, but the availability issue does not make it in my opinion a good choice. A 308 win solves the problem. Plus the rise over the run is much better.

SuedePflow
January 27, 2014, 11:00 PM
but the availability issue does not make it in my opinion a good choice.
I've had no availability issues with .223 brass, .308 projectiles, or Blackout die sets... ;-)

justice06rr
January 28, 2014, 04:05 AM
There are plenty of other potential rounds that can cross load into guns they don't belong in, a shooter at the range should keep his ammo distinctly marked so that the wrong combinations don't happen. That should be common sense, but it's something we all have to learn, sometimes for the second or third time.

This is a very good point.

9mm will fit into a 40sw as well and fire. But we don't see LEA's getting rid of Glock 17 over Glock22's.

Mistakes do happen. Hopefully proper training and safety is always key. When using 300BLK, users need to pay more attention not to load it into 5.56 rifles.

Gtscotty
January 28, 2014, 09:10 AM
9mm will fit into a 40sw as well and fire. But we don't see LEA's getting rid of Glock 17 over Glock22's.

I agree that we all need to be careful and methodical with our ammo, but this is an apples and oranges comparison. A 300 blk in a .223 will cause an over pressure situation, likely a destroyed firearm, and possibly shooter injuries. A 9mm, on the other hand will just rattle harmlessly down the barrel of a 40. Shooting an over-sized bullet down a bore is a much different situation than shooting an undersized bullet down a bore.

Warp
January 28, 2014, 09:38 AM
... I suspect after a few more incidents like this we will see a lot of used Blackout uppers and reloading components for sale.

I don't think so.

Warp
January 28, 2014, 09:40 AM
I agree that we all need to be careful and methodical with our ammo, but this is an apples and oranges comparison. A 300 blk in a .223 will cause an over pressure situation, likely a destroyed firearm, and possibly shooter injuries. A 9mm, on the other hand will just rattle harmlessly down the barrel of a 40. Shooting an over-sized bullet down a bore is a much different situation than shooting an undersized bullet down a bore.

Agreed.

In fact, I can *raise my hand* for the 9mm down a .40 question (BTDT). No harm was done to anything, although I learned to pay closer attention

I've had no availability issues with .223 brass, .308 projectiles, or Blackout die sets... ;-)

Powder.

I mean, if you can link to in stock, well priced H110, W296, or A1680 from a reputable retailer, please do.

It isn't enough to avoid the cartridge altogether, but there most certainly are availability issues affecting 300 blk.

I'm too picky, I guess.
I've never built a car. But I have changed tires, fuel pumps, water pumps, one carburetor (do they still make them?), rings and pistons. But I've still not built a car. Must be the way I think, all confused.

I still don't consider it likely that 'Uncle' will ever switch over to the .300 AAC Blackout. Again, my way of thinking, as a general issue item. This doesn't remove most anything from some special operations need some place down the line. I wouldn't think of a M1A as being the normal 'COPs' weapon. But I carried one on a special assignment.

I don't know 'nutin'. Just ask my oldest grand daughter. She's at that age...

Did you buy a chassis, an engine, a transmission, a body, suspension components, etc, separately, and then put them all together to form a fully functional automobile?

jerkface11
January 28, 2014, 09:43 AM
Originally Posted by Edarnold View Post
... I suspect after a few more incidents like this we will see a lot of used Blackout uppers and reloading components for sale.

No after an incident like that you no longer have a 5.56 and a .300blk.

Gtscotty
January 28, 2014, 09:47 AM
I mean, if you can link to in stock, well priced H110, W296, or A1680 from a reputable retailer, please do.

Dang it, Is that where all the H110/W296 went? The 300 BLK folks are shooting up all my 44 Mag powder!

Warp
January 28, 2014, 12:12 PM
Dang it, Is that where all the H110/W296 went? The 300 BLK folks are shooting up all my 44 Mag powder!

That is exactly where it went. H110 is THE go-to powder for supersonic rounds in 300 blk. It can be used for subs as well.

A1680 is THE go-to for subsonic.

lil 'gun is also pretty widely used.

Even 2400 is being grabbed by people desperate for something that will work. A a few others too.

Your magnum handgun powders are not safe!

SuedePflow
January 28, 2014, 12:19 PM
Powder.

I mean, if you can link to in stock, well priced H110, W296, or A1680 from a reputable retailer, please do.

It isn't enough to avoid the cartridge altogether, but there most certainly are availability issues affecting 300 blk.
My local supply shop has plenty. The shelves is full. Last time I was in there, I picked up A1680 and AA#9 for Blackout (they probably had others, but I was mostly buying .223 powders that day). I'd link them to you, but they don't have an online store.

For some people, powders for many specific calibers are tough to find right now. Especially if the internet if your only source. But that's not a Blackout specific problem.

Warp
January 28, 2014, 12:28 PM
My local supply shop has plenty. The shelves is full. Last time I was in there, I picked up A1680 and AA#9 for Blackout (they probably had others, but I was mostly buying .223 powders that day). I'd link them to you, but they don't have an online store.

For some people, powders for many specific calibers are tough to find right now. Especially if the internet if your only source. But that's not a Blackout specific problem.

You are lucky, that is exceptionally rare.

Hopefully the prices aren't really high and you aren't dealing with small purchase limits (or you are close enough to make trips on multiple days without hassle)

SuedePflow
January 28, 2014, 12:45 PM
Hopefully the prices aren't really high and you aren't dealing with small purchase limits (or you are close enough to make trips on multiple days without hassle)
That is the one downside. It's a 2hr round trip (I have friends in the area, so it's not a one-purpose trip), and they do implement purchase limitations, but I don't usually go alone. Where there's a will, there's a way. I'm just happy to find a healthy selection.

Last time I went that way (3 weeks ago), I came home with 18 lbs between two stops.

Warp
January 28, 2014, 01:18 PM
That is the one downside. It's a 2hr round trip (I have friends in the area, so it's not a one-purpose trip), and they do implement purchase limitations, but I don't usually go alone. Where there's a will, there's a way. I'm just happy to find a healthy selection.

Last time I went that way (3 weeks ago), I came home with 18 lbs between two stops.

Like I said, there most certainly are availability issues affecting 300 blk.

You listed SW Michigan so I didn't ask, but I don't suppose you are referring to Johnson's in Adrian? Probably not, that is definitely SE Michigan.

But anyway, I picked up 1lb of W296 and 2 lbs of A1680 at the shop in Adrian just before Christmas.

And then I snagged these from an online shop (<$25/lb delivered) last week. Arrived yesterday.

:cool:

http://i41.tinypic.com/t0hrfd.jpg

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