300 blk question

[ineedaname]

I was under the impression the 5.56 and 300 blk used the same upper,true or false?

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[DirectDrive]

I was under the impression the 5.56 and 300 blk used the same upper,true or false?

Impossible.
One is shoots .224 dia boolits and one shoots .308 dia boolits...the barrels are different.
Now the bare upper could be used for either.

 

[ineedaname]

that's what I thought but I keep seeing people selling 300blk uppers so I thought I would check

 

[DirectDrive]

that's what I thought but I keep seeing people selling 300blk uppers so I thought I would check

Of course you could sell (or possess) a 300 BLK upper.
?

Edit:
OK, let's say I have a complete AR15 lower.
I also have a complete AR15 5.56 upper.
And I have a complete AR15 300 BLK upper.

I can install the complete 5.56 upper in about 2.5 seconds and shoot 5.56 ammo
Then I can break it down and install the complete 300 BLK upper and shoot 300 BLK ammo.

 

[ineedaname]

That is true,its all in how you word it I guess,,just checking

 

[v0lcom13sn0w]

its just a different barrel

 

[DirectDrive]

That is true,its all in how you word it I guess,,just checking

I suppose you could say that there are 3 levels of the state of an AR upper :

1) Stripped (the bare, machined forging or machined billet, usually anodizing is done)
2) Assembled upper (dust door and forward assist installed)
3) Complete upper (Receiver, charging handle, BCG, barrel and handguard installed)

 

[American123]

I REALLY want to make sure this is well understood.

Here is what is REALLY important to understand:

• both 300 blk out and 5.56 uppers can be interchanged on a AR15 lower because they both operate from the same platform, (the AR15 lower),
  
• 300 blk out uppers and 5.56 uppers utilize all of of the same components, BCG, CH, gas tube, etc. EXCEPT FOR THE BARREL
• 300 blk out barrels fire a 30 caliber bullet, it is a 300 blk out cartridge (the diameter is .308, but it is not a .308 cartridge, metrically known as 7.62x51)
  
• 5.56 uppers have a barrel that fires a .223 caliber bullet (metrically known as 5.56x45)
• DANGER: Because the case dimensions are very similar (this was designed purposefully) If you accidentally fire a 300 blk out cartridge from a barrel designed for 5.56 / .223 you will destroy your gun and very likely injure yourself
• Many shooters own uppers in 5.56 / .223 and an additional one in 300 blk out. They do this so that they can shoot two different cartridges using the same magazines, and using the same AR15 lower by simply switching the upper. The DANGER of this, is if you are not paying very close attention and very aware of what you are doing with your two different uppers. You might accidentally put a magazine filled with 300 blk out in to the rifle when the 5.56 / .223 upper is mounted and then have a rifle destroying kaboom when fired. A similar situation was shared by a member here of that type of thing happening which is why it is very important if you are ever shooting with friends and have your 300 blk out ammo and 5.56 / .223 ammo at the shooting location that either you solely control the loading of the magazines or that you completely remove the 300 black out related ammo and upper from the situation until you are going to shoot 300 blk out, and then completely remove the 5.56 / .223 ammo and upper from the situation while you are shooting 300 blk out because you don't want a ignorant person to want to switch back and then mix up the ammo which would result in a KABOOM
• This very explicit post may seem very easy to understand, but it is very important to not ignore these points because there are many many examples of people failing to follow these points and blowing up their gun and hurting themselves or someone else as a result.

 

[Wombat of Doom]

Just throwing this out there because I have heard of people having accidents here. The muzzle devices are different too. DO NOT use a .223 device on a 300blk barrel!

 

[DirectDrive]

I like but, it's .224 diameter....
Most all the Hi-Power .22's choot .224 dia boolits.

 

[Tomahawk67]

I suppose you could say that there are 4 levels of the state of an AR upper :

1) 80% (the final 20% of the machining process is not done)
2) Stripped (the bare, machined forging or machined billet, usually anodizing is done)
3) Assembled upper (dust door and forward assist installed)
4) Complete upper (Receiver, charging handle, BCG, barrel and handguard installed)

What is an 80% upper?
You must mean 80% lower.

 

[DirectDrive]

What is an 80% upper?
You must mean 80% lower.

Yeah, you're right.
No value in an 80% upper LOL.
I'll have to edit that.

 

[American123]

I like but, it's .224 diameter....
Most all the Hi-Power .22's choot .224 dia boolits.

You are correct, but for the purpose of information sharing, I didn't want to even bother saying .224 because then that could set off even more confusion how it is called .223 Remington but it fires a bullet with a diameter of .224 of an inch.

(Especially considering the main point of this post was making sure the difference between 300 BO and .223 / 5.56 were understood from a rifle configuration standpoint, it's kind of like, "I could teach you 1 million things in the same time period but if I do that all at the same time you will remember only 1 of them if I'm lucky, if I teach you a couple things (ignoring the finer details of other parts) you can learn a couple things really well and then I can incorporate the finer details later"

Like for example .223 Remington fires a bullet with a diameter of .224)

Pretty good information all in all in this thread. I just wish the Brass costs and cartridge costs would come down to about .30 cents a pop. Hard to justify getting into 300 BO for me when I can shoot .308 for the same price and ballistically speaking, shoot a very similar cartridge, 7.62x39 for $.22

Haven't got into suppressors yet so I suppose when I do, at that time it could be more appealing, although if you are shooting suppressed and subsonic 300 BO in CQB scenarios you are basically firing a .45 ACP suppressed..... so once again, why would I pay more to do the same thing a .45 ACP could.

 

[DirectDrive]

You are correct, but for the purpose of information sharing, I didn't want to even bother saying .224 because then that could set off even more confusion how it is called .223 Remington but it fires a bullet with a diameter of .224 of an inch.

Yep, it was a revelation when I first bought .224 bullets to reload for my .222

 

[American123]

Yep, it was a revelation when I first bought .224 bullets to reload for my .222

Or how .270 win actually has a bullet that is .277 I believe.

I think where it is good to explain the conceptual understanding of it ballistically. If the bullet was the exact same diameter as the barrel ID then there would barely be any contact with the lands of the rifling and we would not get good spin and accuracy would suck, because the bullets are a fraction of a hair wider than the barrel ID it causing the bulllet to spin as a result of contacting the rifling which provide us a more accurate flight path of the bullet.

(Nothing new to most of us, but a lot of shooters have little concept of what is going on every time they've pulled the trigger)