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Old January 14, 2015, 05:15 AM   #1
Beretta686
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300 Blackout Worth It?

I have a 7.5" 5.56 upper that I run on an M16 and SBR lower. It's pretty cool to pull the KX3 off and shoot at night to see the massive fireball, but mostly it's a useless play toy.

I'm thinking of making it an 8" 300 Blackout to run with my SOCOM can. However I'm not sure it's worth it, as I probably won't do much with it other than plinking and the occasional hog hunt.

Some considerations:
>I don't reload and am not much interested in it
>All I'd need is a new barrel and a mount for my SOCOM and I'd be good-to-go. No new cans, optics, registered lowers or an upper.
>I have other projects that selling the upper in 5.56 would finance.

Does anyone have first hand experience with a 300 Blackout and does it do something amazing, or is it more just a cool thing?
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Old January 14, 2015, 08:30 AM   #2
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300AAC=125 grain bullet + 17-19 grains of H110
357 mag= 125 grain bullet + 17-19 grains of H110
(neither is a specific loading recommendation)

Expect similar results from an 8" barrel although the 300 has an advantage over longer range.
I've given some thought to adding a 300 AAC barrel(10-14") to my AR "pistol" as a compact "can platform" but the overall performance seemed questionable so that hasn't happened YET.
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Old January 14, 2015, 12:23 PM   #3
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They are really fun and light recoiling. I push 100gr bullets to close to 2400fps for supers or 230gr at 1059 for subsonics. But if you either don't reload, or don't plan to get a silenicer, I wouldn't do it. Just too pricey to shoot; and I see the popularity waning lately; so I don't see it coming down in the future. I LOVE mine, but i cast and reload
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Old January 15, 2015, 01:09 AM   #4
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The 300 Blackout is merely the 300 Whisper, repackaged and renamed. 300 Blackout and 300 Whisper chambered guns are interchangeable.

Here is an article that adequately sums up some of the issues with the 300 Blackout:

http://www.alloutdoor.com/2014/05/22/300-aac-blackout/

My main issue with the 300 Blackout are two fold:

1. You can accomplish the same or nearly the same goal of a quiet round by shooting a subsonic .223. Here is some data for subsonic 223 loads: http://www.survivalistboards.com/sho...d.php?t=306212

You will also solve some of the issues in the article posted above by shooting a subsonic 223, rather than a 300 BLK, most specifically the cycling issues and the suppressor requirement issue (shooting a 300 BLK in an AR without a suppressor will result in cycling issues).

2. The rediculous cost of 300 BLK: it's just a .223 that costs 4-6 times more. The main culprit is the .308 bullet, which costs significantly more than a .224 bullet. The other components cost the same in both the .223 and the 300 BLK (the cost of the brass can be amortized into insignificance by reloading the brass, so I don't count the brass), but the bullet is the most expensive component. I haven't shot a factory round in years, so I have no idea what a factory BLK round costs, but I am sure the factory cost is correspondingly high.

If you shoot full auto, then get ready to pay belt fed 308 prices in an AR that's meant to shoot a 223. That's going to hurt.

The 300 BLK is a well marketed item, though.

Did you know that Patagonian Sea Bass was originally thought to be disgusting, and no one ate it? Then it was repackaged, remarketed, and renamed as the Chilean Sea Bass (it's not even in the bass family). Now it's high end gourmet food that sells at $50 a pound: http://priceonomics.com/the-inventio...lean-sea-bass/

Good job by the Advanced Armament Corportation of essentially bringing to life a failed and forgotten round.
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Old January 15, 2015, 05:56 AM   #5
Bartholomew Roberts
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I don't know what Machineguntony is going on about; but .223 subsonic is going to give you a lot more feed issues than .300 BLK will - and you'll essentially be shooting an expensive .22LR instead of an expensive 9mm FMJ that penetrates 21"+ of gel.

.300 is about the only AR caliber I know where you can cycle supersonic, subsonic, suppressed and unsuppressed all from the same rifle without an adjustable gas block.

For really short barrels (6"-9"), I think it is an improvement. You get decent ballistics (110gr at 2180fps out of a 9" barrel) without the giant flash. It is definitely a niche round though. What are you wanting to do with it?
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Old January 15, 2015, 07:18 AM   #6
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I have to disagree tony " You can accomplish the same or nearly the same goal of a quiet round by shooting a subsonic .223". so your saying that a 75gr .223 going 1050FPS is the same as a 230gr .30 going 1050FPS? and the 300 has no feeding issues. there is a play of balance getting your subsonic right up the edge of the sound barrier and keeping it cycling properly, but I wouldn't call that an issue, it's pretty easy to do. I am not a gun pro or anything and I have had zero cycling issues with my home built and very cheap 8" barrel. how on earth can you slow a .223 from 3000fps down to 1000 and not have cycling issues. I would assume your going to need to do some work on your gas system, thereby making supersonic rounds overgassing when you switch.

not sure if you read the thread you posted, but it clearly said that the loads wouldn't cycle their ARs and they were talking about conversion kits with weaker springs etc.
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Old January 15, 2015, 08:21 AM   #7
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Quote:
I don't reload and am not much interested in it
This makes the answer a no
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Old January 15, 2015, 09:34 AM   #8
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Quote:
You can accomplish the same or nearly the same goal of a quiet round by shooting a subsonic .223.
If all you want to do is punch paper with a muffled noisemaker, subsonic .223 will do it...... 62 gr bullets at ~1000f/sec will tear up some paper just fine but so will 60gr supercolibris. Anything more practical, you'll need some bullet weight.
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Old January 15, 2015, 10:37 AM   #9
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Tony,

That article is full of inaccurate, misleading and just bad info.

First hand experience with this cartridge and about 20,000 rounds downrange (80% supersonic/ 20% subsonic) has shown me the strengths AND weaknesses of this cartridge.

So here goes...

First, unless you are independently wealthy, you must reload for this cartridge to shoot it much. Factory ammo is around $1 / round. Reloading can cut that down to about 25c /round. Which is about what you pay for 223

Second. Its no powerhouse. But, it does deliver about the same ballistics as a 7.62x39 round with supersonic ammo. 110-125 grain bullet at 2200-2300 fps

Third, a subsonic 223 will be a single shot. No standard AR is going to cycle 223 at subsonic velocities and pressure levels. The 300blk will function. No changes made to the gun...just swap mags and go from supers to subs. AND you dont have to use a can to get it to function. My 9" 300blk runs supers or subs...can or no can

Forth, the 300blk works VERY well out of short barrels. The OP mentions the flamethrower 7" 223 gun he has. That flame is wasted energy. All that powder burning after the bullet leaves the barrel does nothing to help balistics. The 300blks use of powder is much more efficient. Almost zero flash from a 9" barrel and very little velocity lose going from a 16" to a 8-9" barrel.


So to sum the advantages up...

Ive got a gun thats
The size of an MP5
Got the ballistics of an AK
The ergonomics of an AR
The flexibility to shoot supersonic or subsonic ammo with just a mag change
And suppresses well if you want that

Disadvantages
COST of ammo (this is negated by reloading)

OP...one of the advantages is the ability to check out this caliber with no more investment then a barrel swap. Thats how i started. I threw a 16" 300blk barrel on one of my ARs and started tryin it out.
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Old January 15, 2015, 12:21 PM   #10
Bartholomew Roberts
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I'd add that if you buy in bulk and shop around, you can get remanufactured .300 BLK in the $0.55-0.67/rd range. Luckygunner is selling the 168gr BVAC right now (a Fusion softpoint at about 1400fps out of a 9" barrel). It makes decent plinking ammo.

Several places sell pulled 147gr NATO bullets loaded in .300. I've yet to have much good to say about them; but they are cheap and go bang.
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Old January 15, 2015, 01:56 PM   #11
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and if you do not want to go suppressed, Wilson Combat combat came out with the 7.62x40 WT, essentially made the same way as .300BLK, but has more case capacity. also only requires a barrel change. but again, reloaders only. I am pretty interested in the chambering, but I am afraid it would cause too much confusion with my 300BLK and I would blow something up......
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Old January 15, 2015, 02:11 PM   #12
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The 7.62x40 either loses a cpl rounds in a standard mag or takes special mags to get full capacity. 300blk uses standard 556 mags at full capacity

If i was building a straight up hunting rifle. For deer/pig sized game the 762x40 would be a winner. As a SBR/defensive rifle the 300blk is better

Last edited by Sharkbite; January 15, 2015 at 02:30 PM.
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Old January 15, 2015, 02:47 PM   #13
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it uses .223 brass jst like blackout, how would it lose capacity?

it says you need do download by one round, just wondering why?
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Old January 15, 2015, 03:33 PM   #14
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Quote:
it uses .223 brass jst like blackout, how would it lose capacity?
because it moves the ogive of the bullet further forward, most 5.56 mags have a rib just forward of the shoulder and these ribs are too close together for 30 cal projectiles to stack properly.
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Old January 15, 2015, 03:56 PM   #15
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^^^this^^^

The x40 round seats the bullet out to far and causes rounds to not stagger properly in the mag. 300blk is short enough thats not a problem
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Old January 15, 2015, 05:32 PM   #16
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I get it guys. We love what we love. That's the beauty of having options.

Heck, I love Chilean sea bass and my George Forman grill. It's just a waffle maker, people!
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Old January 16, 2015, 11:17 AM   #17
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Wilson machines the rib on Lancer mags to clear the ogive. He sells them for his rounds. IIRC he doesn't recommend using any other.

As the 6.8 community learned long ago, mags are cartridge dependent and changing just one dimension can make them a nogo. With .300BO, it gets by.

As for a .300BO gun being able to shoot any round, supersonic or not, suppressed or not, without an adjustable gas block, well, it's luck of the draw. It's known that tuning the AR for low pressure cycling results in much harsher action at full power. A .300BO gun running subsonic unsuppressed well may not be what is best when shooting supersonic suppressed.

That may not have been the intended thought but blanket statements allow others to draw a generalization like that. And reloading to fit each circumstance allows that sort of thing, when in practice the budget shooter handling off the shelf rounds may have issues.

Those supersonic unsuppressed rounds are also going to follow the ballistic curve of most bullets with larger frontal areas. They all suffer from reduced range and higher amounts of bullet drop. That alone makes the .300BO an intermediate to close range cartridge, whereas others are quite well known to reach out 200m further just as effectively.

It's a matter of tradeoffs, and exactly why the .300 x 5.56 never made it as a viable 3Gun cartridge in the 80s when it first came out. Expensive and short ranged.
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Old March 19, 2015, 03:22 PM   #18
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My lancer mags don't have ribs!!!!
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Old March 19, 2015, 04:17 PM   #19
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Since you already have a can the .300 is a no brainer. Suppressed subsonics are a hoot and get plenty of looks at the range.
I current have two AR's chambered in .300 and am in the process of building a third. Also have put a few thousand rounds in this caliber down range over the past couple of years. What I do know is 8-9" barrel is ideal for heavy (208 & 220 grain) subsonic's suppressed and there is no advantage of going to a longer barrel. As for light supersonics (110 & 125 grain) you will loose about 250fps over a 16" barrel but can still achieve 2000 -2100 fps which is more than enough to drop hogs with Barns Black tips or Hornady V-Max bullets.
The other only negative I can think of is if you don't reload ammo can be a bit on the expensive side. If you do reload the cartridge has been out long enough that there is plenty of data for bullets ranging from 110 grain all the way up to 240 grain cast.
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Old March 19, 2015, 05:32 PM   #20
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I've posted charts from this program in other threads before- I use it at work constantly to get a general idea of comparisons between cartridges or bullets within the same cartridge. It is the Federal Premium Ballistics catalog and it is a free download online if anyone else feels like playing with it!

A toy is a toy and if you want one there is no reason not to build it. But if you're looking for performance, there are WAY better options than the 300 BLK. These two charts are comparing the Velocity and Energy of a standard .223 round to a standard .300 BLK round.

The appeal of the .300 BLK is that you can use an AR platform to lob a .30 cal bullet that is subsonic and therefore worthwhile to suppress without sacrificing mag capacity. These charts are based on an 18" barrel too, so obviously you'll be losing a bit more on top of what these show.

Just food for thought. I just plain don't understand the use of this cartridge outside of specific military applications, but other people totally get off to it so maybe I'm just missing something...
Attached Images
File Type: png 300 ACC BLK.png (31.0 KB, 60 views)
File Type: png 300 BLK Energy.png (29.3 KB, 52 views)
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Old March 19, 2015, 09:01 PM   #21
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it's the ideal for a HD pistol. throw a simple reflex and a short barrel, and I can't think of anything that does a better job of maneuvering through my home while still having substantial power. so I don't care what it does past 50 yards, or even 25 yards for that matter. what's the way better option for my use?

your graph is a 220gr versus a full-power 223. how about a 110gr 300blk versus a .223 for short-range application, then you'll get the idea.
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