I'm looking for thoughts and opinions on a 300 AAC Blackout upper build. Reason behind the build is I have a lot of .308 bullets in various weights that I reload for 30-06. 308 Winchester/7.62 NATO, 300 Win Mag, etc so ammunition would not be a concern.

 

I'm likely going to use this for short range target shooting/fun at the range.

 

Let me know if you have any experience with this caliber and what you think of it.

 

Also, if anybody has a link to a cheap but reliable barrel please share. I'm not sure what length is best in this caliber for fair to descent target shooting but would like something that can keep 5 rounds in to a 2-3" group at 100 yards.

 

I already have a .750 gas block, YHM hand guard, upper receiver (+kit), gas tube, muzzle break, roll pins and all other parts so just need the barrel.

 

Thanks fellas,

dgp1000

^{I have a friend back home (Tx) who is VERY into this caliber. I'll try to pick his brain in the next few days and see if he can answer your questions.}

My Thoughts:

It was designed to be able to fire a .30 cal projectile out of a standard AR-15, using the same bolt, BCG, magazines, buffer, buffer spring, etc., with the only requirement being a barrel change. This allows a lightweight platform to fire a 115-147gr .308 bullet, out of the most standard weapon in use by law enforcement and the military (with a huge amount of civilian shooter with AR15s as well).

 

Suppresion/subsonic is just a benefit of the round design. I've shot subsonics through my Blackout Upper and it sounds a hair louder than a .22, and it's pushing a 220 grain projectile. So don't get to hung up on not having a suppressor, as even the super sonic rounds are pretty quiet compared to their .308 counterparts,

 

Some of the hot topics about 300 Blackout:

"300 AAC Blackout has as much energy from a 16 inch barrel as 5.56mm from a 24 inch barrel. You get 8 inches of barrel for free."

 

"300 AAC BLACKOUT, due to the larger bore than 223, is very efficient in shorter barrels, and we have had good functioning results with AR barrels down to 6.2 inches."

 

"300 AAC Blackout has a little less energy at the muzzle(than 7.62x39), but due to higher BC bullets, it is equal by around 110 meters, and by 300 meters, the Remington 125 grain Match ammo has 16.7% more energy than even the hot Lapua 7.62x39mm ammo."

 

Regarding accuracy, I can shoot right around 1 MOA out of my upper at 100 yards off a bench, so it's definitely combat accurate.

Potency, it's a landslide. IMHO, there is no better round ballistically inside 250 yards for all purpose defensive use. The 147gr carry a metric ton of energy downrange, and it was rated combat effective to 410m out of a 9" barrel by the military. The new Barnes bullet apparently is pretty devastating as well.

 

Recoil impulse is less than or equal to a 5.56, and this was confirmed with 2 others who shot my 5.56 and 300Blk uppers back to back.

 

Light as you can make your AR, so no added bulk like you get with a 6.8 or .308 AR platform.

 

30k round estimated barrel life, due to the relatively low PSI of the cartridge.

 

Out of a 9" barrel, you're getting a 125-147gr projectile at 2,000 ft/s, with 1,100 ft-lbs at the Muzzle. That's roughly 25% more than 5.56 M855 out of a 9" barrel.

 

 

Regarding reliability - the system has to be run wet. At least that's been my experience. I can shoot both super and subs through my AAC 16" barrel without issue. I originally had trouble short stroking with subs - but once I swapped to a standard carbine buffer I was good to go.

 

It's not a round for the masses, but the SAAMI spec and the fact that it's been picked up by over 60 firearms & ammunition companies (barrels, reloading supplies, ammo, etc.) does make it an interesting choice. In NJ it's not as cut and dry, since the round excels out of short barreled rifles, and with suppression. However I really enjoy mine.

 

http://njgunforums.com/forum/index.php?/topic/37217-300-black-out-whats-your-thoughts/page__fromsearch__1

 

http://njgunforums.com/forum/index.php?/topic/36546-caution-rem-umc-115gr-300blk-packaged-with-live-223-rds/page__fromsearch__1

Well it sounds to me like if I built one of these I'd use it a lot since I'm not seeing much in the way of negative feedback and the above info has some really interesting facts. Thanks TM!

 

Can anybody recommend a barrel manufacturer that's on the cheaper side? I'm looking at CMMG barrels right now. Has anybody had any experience with these?

 

Also, I know there are variants of this round out there such as the "Whisper" and the 7.62x40m Wilson Tactical which I know is not quite identical but is also worth a look. Of all of the variants, is the 300 BLK the only version that has been SAAMI recognized? I don't particular want to build a wildcat that I'll need to buy a ton of brass for before it's phased out.

I'm in the process of building a 300 blackout AR with this upper/lower:

 

 

At this point I'm 90% sure I'm using Black Hole Weaponry polygonal rifled 18" barrel with a midlength gas system. The rail is either going to be a YHM Rifle Length Diamond Forearm or a Midwest Industries Rifle Length Gen2 Two Piece Free Float Handguard with a low profile gas block. JoJo's in Connecticut is going to manufacture a brake for it out of a .308 A2 flash hider and pin/weld it on the barrel. I also have my heart set on a Leupold 1.5-5x20 Mark 4 MR/T with a .300 Blackout reticle but at $1400 that might be much later on. Hopefully I will get to finishing this before the holidays after my Block II build is done.

That's a great looking setup you have there. I have everything I need but a stripped upper receiver and a barrel. I'm trying to keep the cost down as low as possible on this one and was hoping to find a barrel for <$200. Why are you going with an 18" over say a 16"?

I figured a midlength gas system 18" should translate into a higher muzzle velocity which the round seems to suffer from with 14.5" and 16" carbine length gas systems. I think it will look pretty sweet as well, I have 14.7" (16" overall with brake), 16" and 20" barreled ARs, I don't yet have an 18", so I need one. ;-)

 

I figure around an average of 2270fps from a 16" vs. about 2500fps from an 18".

 

*300AAC fps vs barrel length:

Well if you have to have one, you have to have one!

 

I decided on a 16" surplus barrel "Surplus Ammo & Arms 16" Carbine H-Bar 300 Blackout Stainless Steel 1:8 AR-15 Barrel" for $199.99. I've completed a nice standard 5.56 configured carbine lower so when the barrel arrives I just need to finish up the upper and have somebody pin and weld a brake on to it for me.

 

TK, Let me know how you how you get on with your build and once completed how it performs and I'll relay the same info for you.

 

Thanks all,

David.

Well if you have to have one, you have to have one!

 

I decided on a 16" surplus barrel "Surplus Ammo & Arms 16" Carbine H-Bar 300 Blackout Stainless Steel 1:8 AR-15 Barrel" for $199.99. I've completed a nice standard 5.56 configured carbine lower so when the barrel arrives I just need to finish up the upper and have somebody pin and weld a brake on to it for me.

 

TK, Let me know how you how you get on with your build and once completed how it performs and I'll relay the same info for you.

 

Thanks all,

David.

 

Will do.