AR-15 in .300BLK (300 Blackout)

[esrice]

The cold hard truth is you arent gonna carry both a 5.56 and 300 BLK upper and ammo with you if you ever "have" to use them. Looks like there isn't really any advantage.

You're comparing the 5.56 to the .300blk. The advantage comes in .300blk vs .308win or 7.62x39.

For someone who wants .308 caliber projectiles in an AR platform, the .300blk is a killer option.

 

[jblomenberg16]

I guess if I was on a "super secret" mission this would be icing as you say. The cold hard truth is you arent gonna carry both a 5.56 and 300 BLK upper and ammo with you if you ever "have" to use them. Looks like there isn't really any advantage. The ammo price difference speaks volumes.

Well, I'm not planning any super secret missions anytime soon, but I do intend to enjoy the heck out of shooting this caliber at the range. I'm not sure the point you are trying to make about having both 5.56 and 300BLK with you...how is that any different than having 5.56 and 7.62x39 with you? The point isn't to have a gun that you can do a caliber conversion in the field with a simple swap of the upper (although I guess that is a nice perk), but more of a commonality of parts with what I already own and enjoy shooting.

I also enjoy shooting my AK and SKS in 7.62x39 and have a nice amount of ammo ready to feed them. I am biased as you can tell, especially since I've purchased one. Here's some of the comparisons for the 3 points.

1) A quick search for 7.62x39 bolts returned results that indicated the bolt itself was typically $20 - $30 more expensive than a 5.56 bolt, and many places were out of stock. And, the spare bolt that I keep in my spare parts box will now work for this rifle, and the other 5.56 AR's I have.

2) Reliable Standard AR mags can be found for $7 for metal GI mags, up to $15+ for PMAGs and other higher end mags. 7.62x39 mags for the AR typically cost double that and the selection is limited to a few manufactures.

I happen to have a stash of 5.56 AR mags already, so don't have to invest in any additional mags for this rifle.

3) Yep, it is Icing on the cake for me, because I enjoy reloading for my rifles. In fact, I'm looking at the ability to load .300BLK made from .223 brass I already have, for the same, or less cost than new "surplus" 7.62x39. And, I have the option to load a wide variety of .308 caliber bullets, from 110gr up to 220gr. There simply is not the same variety or selection of .311" bullets for the 7.62x39.


I'm not saying the 7.62x39 is a bad caliber, or that one shouldn't build an AR in that caliber. But I am saying there are advantatges to going the .300 BLK route if you are wanting to do it on the AR platform, which is why a number of people are very excited about it.

 

[mammynun]

Here's my pistol, not so soon to be SBR. Big thanks to Front Toward Enemy Firearms for providing the lower that kick started the project! The lower came in today, and an hour later:

Test firing tomorrow, then passport photos and engraving!

Looking for a deal on a suppressor too!!

 

[shooter521]

Oh my; y'all should have seen the cases upon cases of 115 and 220gr 300BLK ammo at the industry shoot on Monday. Judging by the retailers in line to shoot all the various 300BLK offerings on hand at the range, this cartridge is going to get a LOT of love this year.

 

[esrice]

this cartridge is going to get a LOT of love this year.

 

[rhino]

Even I, Mister I Do Not Like Change, like this idea, either this specific round or something similar.

 

[Crydaddy]

Ha! My hopefully an spr project!

 

[Hop]

Wow mammy that slim Troy handguard sure looks sexy on there. I'm really leaning that way for mine too (in FDE).

 

[jblomenberg16]

Wow mammy that slim Troy handguard sure looks sexy on there. I'm really leaning that way for mine too (in FDE).

I just had one put on my .223 upper (see AR15 pic thread) and love it. Very positive grip, and you can put rails where you want them. And if you don't want any on the sides, it is a nice sleek package.

 

[figley]

In looking at the gel tests of Hornady's two V-Max rounds, I found information that still has me torn on the round.

The 208gr, even though it is sub-sonic, and therefore can be suppressed, doesn't seem to perform well, in terms of hydraulic shock. It gets great penetration, but the wound channel isn't that impressive.

The 110gr, however, appears to be downright explosive. How much benefiit, though, is a suppressor, on a round traveling at 2375fps?


The 110gr projectile has a similar velocity (2232fps), and delivers the same energy (1217ft/lbs), at 50yds, that an equal size bullet, from .308Win. has at 300yds. (2228/1212) Energy delivered by the .300AAC, at 100yds (1071ft/lbs), is roughly equivalent to that of a 75gr., .223 TAP, at the same distance (1092ft/lbs). Energy delivered by the 208gr., subsonic, at the muzzle(480), is slightly less than that delivered by the 75gr., .223 TAP, at 500yds (514).

Hornady Manufacturing Company :: Ammunition :: Rifle :: Choose by Caliber :: 300 Whisper® :: 300 Whisper® 110 gr V-MAX®

Hornady Manufacturing Company :: Ammunition :: Rifle :: Choose by Caliber :: 300 Whisper® :: 300 Whisper® 208 gr A-MAX®

Hornady Manufacturing Company :: Ammunition :: Rifle :: Choose by Caliber :: 223 Rem :: 223 Rem 75 gr TAP® FPD™

Hornady Manufacturing Company :: Ammunition :: Rifle :: Choose by Caliber :: 308 Win :: 308 Win 110 gr TAP® FPD™

One of the greatest advertised benefits of the .300AAC, is its use as a CQB round. Energy delivered by the 208gr load, at the muzzle, out to 50yds, is close to that of a 357 Mag 158 gr XTP®, whereas the 110gr., supersonic round, acts more like a rifle round.

Hornady Manufacturing Company :: Ammunition :: Handgun :: Choose by Caliber :: 357 Mag :: 357 Mag 158 gr XTP®

My main concern, is that the sub-sonic round, due to lower velocity, may act more like a pistol round, than a rifle round. i.e.- it may excessively overpenetrate, maintain velocity, and not fragment, like a 5.56mm projectile would. Another factor, is the size, and shape of the wound cavity. (pistol=straight line, rifle=balloon)

Will a supersonic, 110gr. round, though, act more like a .223, in regards to fragmenting, or dumping its energy quickly? The suppressed feature is negated, but delivered energy is similar, out to 100yds.

I have no agenda, other than to find and compare information. I am curious about this round, and may get into it, but I want to know all the facts before I do.


ETA: If any info here is incorrect, please just correct it, or PM me so I can correct it. After reviewing my post, I confused myself. Maybe I the whole thing, maybe not.

 

[thescrambler]

The 300 ACC Blackout and the 300 Whisper are both tempting but I base my final caliber decisions on ballistics tables.

I compared 30 caliber projectiles for the AR15 platform and the best all around (bullet weight, velocity, trajectory, price per round) was the Remington 30 AR. Core-lokt ammo is $18/box everyday and it is the closest to true 308 caliber ballistics you'll find. The 30AR's parent case was the 450 Bushmaster whereas the 30BLK's was the 221fireball/223rem. And, let's not forget that the Rem 30 AR was developed as a true deer hunting cartridge specifically for the AR15 platform.

The 30BLK has the 220gr bullet but it hits with less than 500ft-lb of force, lats less than a 115gr 9mm +p+ at 519ft-lb and only a little better than a 115gr FMJ hitting at 420ft-lb. The Rem 30 AR has a 150 grain but we need a common bullet weight. So lets compare the 125 grain variations of the 30AR and 300ACCBLK, the 300ACCBLK leaves the barrel going 2215fps and hits with 1360ft-lb. But, the 30AR leaves the muzzle at 2800fps and hits at 2176ft-lb.

Now take those numbers and compare to the 55gr we left behind. Flying at 3240fps and hitting at 1282ft-lb its faster than a 300BLK and doesn't hit with that much less force. The 30AR is only 400fps slower and hits with 69.7% more force.



I wanted a 300 Blackout too, but the numbers don't make sense to me. Maybe I'll build one after I build a 30 Rem AR

JT

 

[esrice]

I wanted a 300 Blackout too, but the numbers don't make sense to me.

The real value of 300BLK isn't solely in its ballistics, but in its versatility and adaptability.

As you pointed out, there are other harder hitting or more accurate rounds out there. But how many of those work with your current 5.56 AR's bolt, magazines, buffer, and only requires a barrel swap?

 

[jbrich]

The real value of 300BLK isn't solely in its ballistics, but in its versatility and adaptability.

As you pointed out, there are other harder hitting or more accurate rounds out there. But how many of those work with your current 5.56 AR's bolt, magazines, buffer, and only requires a barrel swap?

This is exacly what has me sold on building one. No special mags, bolts. almost plug n play to a certain degree. Not to mention the suppressed capability.

 

[rhino]

The 110gr, however, appears to be downright explosive. How much benefiit, though, is a suppressor, on a round traveling at 2375fps?

I suppose that depends on your needs. If you want to minimize all of the sources of sound, you'd obviously still get the crack from the projectile moving faster than sound. On the other hand, it's tough to determine the direction from where the bullet was fired if that's all you hear.

In my case, my interest in suppressors would be to reduce the pressure wave enough to protect my hearing if I need to fire the gun indoors. Whether or not it's audible is immaterial.

 

[jblomenberg16]

Just loaded up my first reloads tonight. Will update with pictures soon. I hope to have some preliminary range results this weekend, bearing in mind that ambient conditions won't be ideal for a true measure of performance.

(left to right)
1) 208gr Hornady AMAX Ballistic Tip over 9.5gr H110.
2) 125gr Nosler Ballistic Tip over 17.5gr H110
3) 147gr .308 Nato puled FMJ over 17.0gr H110
4) Sample .223 with 55gr FMJ for comparison

Goal is to start light and see where I am, then push towards pressure signs once the weather warms up this spring. Would like to see 2100FPS out of the 125, and 2000FPS from the 147. Nosler recommends minimum of 1800FPS for expansion on this, with best performance at greater than 2600FPS (not gonna happen with the 300BLK.)

Goal with the AMAX is to keep subsonic. I may make a few "fun" rounds with this bullet and see what max velocity is before pressure is too great. I would imagine that 1200FPS would be possible.

It will be a while till the can comes in, so for now the 208's will see limited use. Expect that the 147's will be the plinking load due to cost and ease of availability.

 

[figley]

I anticipate the data, after this round is subjected to the Box O' Truth.

 

[shooter521]

.300BLK pr0n:

There were stacks like this at several tables at the AcuSport New Product Shoot... S&W, Daniel Defense, Remington, AAC, CORE15 and DPMS all had guns on-hand in that caliber. Lotta Blackout love goin' on.

 

[awilson82]

I think building a silenced AR in .300Blk is tempting enough to take the plunge and have my first experience dealing with the NFA paper work and whatnot.

 

[Hop]

So I've heard of several people running their 9mm pistol silencers with 300 BLK but ONLY SUBSONIC! Has anyone here tried that? I'm gonna if my friggin stamps ever show up. My problem will be going from a 3 lug suppressor to the correct threads. This might hold me over until I can get a real rifle compatible 30 cal can.

 

[rsilvers]

I put all the latest updates here: https://www.facebook.com/300aacblackout but this gel shot shows how well it works at 300 yards, even from a 9 inch barrel.