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Good Morning
My friends is building a 300 ACC Blackout. His plan is to replace the ar barrel 16 inch with a blackout 16 inch. This is his first build.
The blackout appears to be ainteresting concept.
http://300aacblackout.com/resources/300-BLK.pdf" onclick="window.open(this.href);return false;
Do any of the members have experience with replacing the barrel only for conversion? The references for the 300 ACC Blackout indicate the barrel is the only change. But then "tuning of the weapon" is noted in the references.

I haven't done one yet, but I'll be making one soon. Tuning refers to changing the buffer spring and buffer to adjust cycling. 300 brass is .223 brass shortened and necked for a .308 bullet, so it uses the same bolt. That's why you only have to change the barrel.

Tell your friend to be sure and mark his magazines so he clearly knows which are .223 and which are .300. Not doing so has resulted in devastation.

http://bearingarms.com/300-blackout-in- ... -kaboom/2/" onclick="window.open(this.href);return false;

The problem is that everything but the barrel is the same, including the magazines (obviously), and the results are catastrophic if you screw up. I may go that route one day. If I do, I will use colored tape on every magazine (e.g. blue for .223 and red for .300) and before I insert a magazine, I will double check the barrel and the magazine to make sure I'm using the right ammo.

dcphoto wrote:I haven't done one yet, but I'll be making one soon. Tuning refers to changing the buffer spring and buffer to adjust cycling. 300 brass is .223 brass shortened and necked for a .308 bullet, so it uses the same bolt. That's why you only have to change the barrel.

There is different in .223 vs 5.56 NATO. The 5.56 NATO has a thicker base which allows higher pressures. So, for reloading the 5.56 NATO is the preferred case? The same magazine 5.56 NATO is use for both weapons. So, will a 5.56 NATO round shoot in a 300 ACC Blackout rifle? Will a 300 ACC Blackout chamber in a 5.56 NATO and shoot?

it will chamber and it will go boom when you squeeze the trigger but that, my friend is where the similarities stop...lol

getting a 7.62mm peg in a 5.56mm hole is where the rub happens.

RogueUSMC wrote:it will chamber and it will go boom when you squeeze the trigger but that, my friend is where the similarities stop...lol

Ees boom. BIG Boom. BIG Badaboom! That is why you CLEARLY label which of your 5.56/.223 magazines are to be dedicated for .300 Blackout......to avoid the confusion. Even though it is just a barrel swap, if he plans to have more than one upper for this rifle - as in having both a .300 blackout and a 5.56 upper, he should also designate which upper is which.....even if it means using a different handguard, or color of handguard, or some other way of differentiating which is which so that he knows which magazines to use for which upper.

I built my .300 from a finished palmetto upper and added all FDE moe gear to it. The only mags I load any .300 ammo in are FDE mags, so if it doesn't match I don't use it. Helps keep things separated for me as I don't have any FDE furniture on other guns. As for just doing a barrel, I felt a complete upper was a better path simply because it wasn't really that expensive from palmetto.

The Annoyed Man wrote:

RogueUSMC wrote:it will chamber and it will go boom when you squeeze the trigger but that, my friend is where the similarities stop...lol

Ees boom. BIG Boom. BIG Badaboom! That is why you CLEARLY label which of your 5.56/.223 magazines are to be dedicated for .300 Blackout......to avoid the confusion. Even though it is just a barrel swap, if he plans to have more than one upper for this rifle - as in having both a .300 blackout and a 5.56 upper, he should also designate which upper is which.....even if it means using a different handguard, or color of handguard, or some other way of differentiating which is which so that he knows which magazines to use for which upper.

Channeling your inner Leeloo?

RogueUSMC wrote:

The Annoyed Man wrote:

RogueUSMC wrote:it will chamber and it will go boom when you squeeze the trigger but that, my friend is where the similarities stop...lol

Ees boom. BIG Boom. BIG Badaboom!

Channeling your inner Leeloo?

Multi-pass

The video is impressive suppressed fire.
https://www.youtube.com/watch?v=i90j-HcqfAI" onclick="window.open(this.href);return false;

RogueUSMC wrote:

The Annoyed Man wrote:

RogueUSMC wrote:it will chamber and it will go boom when you squeeze the trigger but that, my friend is where the similarities stop...lol

Ees boom. BIG Boom. BIG Badaboom! That is why you CLEARLY label which of your 5.56/.223 magazines are to be dedicated for .300 Blackout......to avoid the confusion. Even though it is just a barrel swap, if he plans to have more than one upper for this rifle - as in having both a .300 blackout and a 5.56 upper, he should also designate which upper is which.....even if it means using a different handguard, or color of handguard, or some other way of differentiating which is which so that he knows which magazines to use for which upper.

Channeling your inner Leeloo?

If I were a girl, Leeloo would be a worthy goal, LOL.

Given the above about big booms: http://www.thefirearmblog.com/blog/2015 ... 56-kaboom/

Rather than swap the barrel, I just built a complete new upper for my 300.

As mentioned, it is very important to keep you mags labeled.

I only use 20 round mags for 300 and only 30 round mags for my 223.

I have processed a lot of brass for my 300. Be aware that some brass works and some don't. I have had problems with several different manufacture's brass, so I only convert LC and PMC for my Blackout rounds.

I do not have the tools for building a complete upper. So, this followed me home. The price was to good. I was able to pick it up.
https://www.primaryarms.com/Advanced_Ar ... 101716.htm" onclick="window.open(this.href);return false;

Technical Information
Upper Receiver: A3 Flat-Top
Barrel Length: 16"
Barrel Contour: Medium
Barrel Material: 4150 Chrome Moly Vanadium Steel
Muzzle Thread Pattern: 5/8"-24
Chrome Lined: No
Barrel Finish: Black Nitride / Melonite
Twist Rate: 1 in 7"
Chamber: 300 AAC Blackout
M4 Feed Ramps: Yes
Muzzle Device: AAC 51-T Blackout Flash Hider
Gas System Length: Carbine
Gas Block Diameter: 0.750"
Handguard: Knight's Armament URX 3.1 Quad Rail, Free Float
Sights: None
Bolt Carrier Assembly Included: Yes
Bolt Carrier Type: Mil-Spec, Nickel Boron Finish

XinTX wrote:

RogueUSMC wrote:

The Annoyed Man wrote:

RogueUSMC wrote:it will chamber and it will go boom when you squeeze the trigger but that, my friend is where the similarities stop...lol

Ees boom. BIG Boom. BIG Badaboom!

Channeling your inner Leeloo?

Multi-pass
[ Image ]

I love me some Leeloo.