Why did the 300Blk stick with the 5.56 case body?

Discussion about rifles in 300 AAC BLACKOUT (7.62x35mm), hosted by the creator of the cartridge.

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DoubleJ
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Why did the 300Blk stick with the 5.56 case body?

Post by DoubleJ »

I'm assembling parts to send to Liberty for a Leonidas, and in doing so researching the 300Blk and storing info in my brain. While researching, of course I'm coming across a lot of threads on the big bore ARs such as the .450, .458, and Beowolf. What I've noticed on all three is a rebated rim and a larger case. I understand the bolt face on the AR can become a weak point when subjected to more bolt thrust or less lug area, so I get the rim size thing. What I'm wondering is why the 300Blk doesn't have a rebated rim and a larger diameter case so it can equal or surpass the muzzle energy of the 7.62x39. I get the fact that 5.56 or .223 brass is cheap to chop down and re-size, but that can't be the only reason. The only thing I've come up with would be a weaker chamber with thinner walls, as I know the .458 is limited to around 35K PSI. I don't know the pressure limits of the .450 and .50 though. I also know there is a 300 Whisper and a 221-300 something or other that are very similar. Can anyone chime in on this? Will we see a 300Blk-WSM or WSSM at some point?
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Steve U
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Re: Why did the 300Blk stick with the 5.56 case body?

Post by Steve U »

Designed for same mags / capacity as current 5.56.
DoubleJ
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Re: Why did the 300Blk stick with the 5.56 case body?

Post by DoubleJ »

Derp! I knew that, then I forgot. Ok, so mag capacity aside (the 458 also uses mil-spec mags, although you lose about 66% capacity) would it have been possible to make the body a bit larger, drop mag capacity by 4 or 7 rounds, and achieve a more powerful round, or would you still run into chamber strength issues?
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RMcDonald
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Re: Why did the 300Blk stick with the 5.56 case body?

Post by RMcDonald »

The case capacity is as is because it makes for a decent supersonic round but still works subsonic. Larger case capacity makes subsonic harder to achieve.
glennhmd
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Re: Why did the 300Blk stick with the 5.56 case body?

Post by glennhmd »

I believe it all boils down to the design philosophy of the 300blk cartridge.
From what I remember, it was designed to fire .30cal bullets with similar ballistics to the 7.62x39 round for use on an AR15 platform and not change any part except the barrel (same magazine and capacity).
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Twinsen
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Re: Why did the 300Blk stick with the 5.56 case body?

Post by Twinsen »

Also power relates to recoil. It already has more recoil than 223. This was the acceptable amount. There are a handful of more powerful 30 cal rounds for the AR-15. They are higher recoiling and worse for subsonics.
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ThreeHundredTraveler
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Re: Why did the 300Blk stick with the 5.56 case body?

Post by ThreeHundredTraveler »

I looked at all the variants. The 300 keeps things simple. All parts and pieces are the same with the exception of a slightly different chamber and a bigger long hole in the barrel. 30 caliber has probably put more holes in meat of every sort for a long long time. Those holes seem very good at making the live meat dead meat. I have never shot meat that was more than 200 yards away. So the 300 does not need to be more "powerful" for me.

If I could get a side charger and someone made a five inch barrel in 458 SOCOM I would make a nice pistol.

If I could find a very cheap barrel for 300 I would buy a side charger and make a 300 kinda bolt action pistol. Would cut the barrel so there is no gas port and make it about five inches long. Cut down a bolt carrier so there is no protrusion from the lower when using the bolt. Fragmenting bullets and it makes a perfect beside the bed gun using a laser sight.
DoubleJ
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Re: Why did the 300Blk stick with the 5.56 case body?

Post by DoubleJ »

So the general agreement is that every aspect was approached from a KISS point of view?
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glennhmd
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Re: Why did the 300Blk stick with the 5.56 case body?

Post by glennhmd »

DoubleJ wrote:So the general agreement is that every aspect was approached from a KISS point of view?
Exactly. :)

The KISS method should be applied to most aspects of human existence, IMO.
mostholycerebus
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Re: Why did the 300Blk stick with the 5.56 case body?

Post by mostholycerebus »

AKA: Economics, the same reason every single other thing happens in this world.
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