My 300 Blkout rifle build

[Guest SMZRU275]

After the AAC Silencer Shoot, I was hooked on building a 300 Blackout rifle, so I picked up a barrel at the event, and started.

This is about finished. Still need an optic and bolt carrier group, but I headspaced my other rifle's bolt carrier and all is good so I can use it for now.

The set up:

BCM upper

AAC 16" barrel w/ gas block and tube

Daniel Defense OmegaX rail

AAC muzzle brake with 51t ring

S&W MP15 lower

Magpul Trigger guard

Magpul MIAD grip

Magpul CTR stock

Magpul AFGII

Magpul MBUS front and rear

JP Enterprises 3.5lb trigger springs

KNS anti roll trigger pins

standard trigger group and bolt catch

And some updates to 5.56 rifle

Went out a few weeks back and shot the 20 rounds I had for it to try it out. Fired flawlessly.

Added an SOE 1-2point sling.

[Jon_L]

I like it! Nice build.

[Backon4]

So tell me more about this. I've got a lower sitting and am looking for something different. Was going to go beowulf but this has me intrigued. Does anyone do a ready to pin on upper?

[Dolomite_supafly]

So tell me more about this. I've got a lower sitting and am looking for something different. Was going to go beowulf but this has me intrigued. Does anyone do a ready to pin on upper?

Yes, several makers now.

300 blk in Google shopping

In the list above make sure it says 300 BLK or 300 AAC. Those are the most common names.

Intersting part is you can fire 300/211 or 300 Whisper as it is known out of these uppers as well. But you cannot fire 300 BLK out of Whisper uppers unless you ream the neck a bit longer. Otherwise the cartidges are nearly identical. The best part about the 300 BLK is it is a SAAMI spec cartridge now with factory loadings. This is what held the Whisper back for the past 2 decades.

Dolomite

[daveW]

Very nice!

[Backon4]

You suck, lol. Pretty sure you just cost me my next bonus.

[Raoul]

This is very interesting. How's it shoot? I've been leaning towards something in 30 cal. for a while now.

[Guest SMZRU275]

As mentioned about a lot of people are doing complete uppers. But building one is no different then doing a 5.56 rifle. Rumors are they several companies are going to release complete uppers and barrels this fall, and first of the year. The market is starting to jump on this pretty quick since so much of their existing product line works for this round.

The only difference in this and a 5.56 rifle is the barrel/chamber. Uses same bolt carrier group, receivers, mags, etc. It's basically a shortened 5.56 case with a .30 bullet in it. Hell that's how I'm making my own brass is trimming and reshaping LC 5.56 brass.

I've only run 20rds through this, 1 box of the 220gr Remington factory ammo. It shot great, but hard to give a really good overview with only 20rounds. I shot a suppressed full auto ar15 at the AAC event, and that's what got me wanting one. Recoil is nice, typical cycling,etc.

I hope to have a couple hundred rounds make to run through it later this month or beginning of Sept. Still need a BGC, and optic on it to be 100%.

[Raoul]

Looks like CMMG, Olympic and Noveske are shipping uppers now. Thanks for the info, keep us posted as you get more rounds through it please. I am very interested in this round.

Thanks.

[DaveTN]

It's basically a shortened 5.56 case with a .30 bullet in it.

Nice build.

But why would you want this over a .308WIN?

[Il Duce]

Nice build.

But why would you want this over a .308WIN?

Doesn't require a whole new rifle, similar performance, uses same mags and parts as a 5.56.

Edited August 15, 2011 by Il Duce

[Guest SMZRU275]

Exactly! I mean if you want to change a current 5.56 riffle over just change the barrel and headspace check your current BCG.

I was already set up for reloading 5.56, so to be able to do these I just needed the die set, bullets, and powder. Trimmers, shell holders, etc all cross over fine.

[Dolomite_supafly]

Nice build.

But why would you want this over a .308WIN?

Another reason is for suppressing. I know you can load a 308 to subsonic velocities but they won't cycle an action the way the 300 can. There is nothing more satisfying than having steel ring louder than the shot itself.

Dolomite

[MacGyver]

There is nothing more satisfying than having steel ring louder than the shot itself.

Dolomite

That pretty much sums it up

[DaveTN]

Another reason is for suppressing. I know you can load a 308 to subsonic velocities but they won't cycle an action the way the 300 can. There is nothing more satisfying than having steel ring louder than the shot itself.

Yeah… I noticed the “subsonic†on that box after I ask.

Doesn't require a whole new rifle, similar performance, uses same mags and parts as a 5.56.

Either SMZRU275 has some big azz hands or that’s a pretty small looking round to be comparing with a .308 Winchester.

That’s pretty amazing.

[Backon4]

Now subsonic 308 with a suppressor on a bolt action savage, same thing. Sounds like a bb gun until you hear the clank on the steel. I was in shock.

[Guest SMZRU275]

Size comparison. Left is Tula .223 55gr and right is Remington 300 AAC Blackout 220gr

[MacGyver]

Looking good!

[Guest SMZRU275]

And it is finished. The Bravo Company BCG and charging handle arrived and are installed. I headspaced the BCG and all the function checks are good. If no rain Sunday taking it out.

[dlm37015]

i have had a 300 whisper for years with a 220 grain round nose bullet it makes a very quiet deer rifle

[Guest BCMFAN]

What's the average cost per round for factory 300 aac?

[William_Munny]

Can anyone post the ballistic information for this round? Seems very interesting, I want to see the chart and compare it to a .30 Remington AR.

[mikegideon]

Here's some stuff. Interesting caliber...

300 AAC BLACKOUT (300BLK)

[William_Munny]

Here's some stuff. Interesting caliber...

300 AAC BLACKOUT (300BLK)

Thanks! Looks like a very viable pistol round but I'm not so sure it can be an effective long or medium range rifle round... Grendel, 6.8 SPC, and .30RAR trumps this round, which really makes sense because the cartridge can't hold enough powder to sufficiently push a .308 bullet with any authority...

BTW, I think the ballistic information is a bit optimistic, IMO.

[mikegideon]

It looks to me like it's equivalent to an AK. The beauty of it is that the case and rim are the same size as a .223, so all the parts except the barrel are stock.

Me... I already settled on the .458 SOCOM. Not a long range round either. It will just slap the bejesus outa something if it's in range.

EDIT: BTW... the problem with any of the bigger AR-15 rounds is getting enough push behind the bullets. The gun itself isn't going to support something with the same snort as a .308

Edited September 17, 2011 by mikegideon