I have 5.56 which never has impressed me much, 7.62 x 39 on AR platform which does impress me, and a 6.5 Grendel AR which is fairly new to me....seems awesome so far.

Kinda have the itch to try the BLACKOUT, but it seems to really be a souped up 30 carbine, or a throttled 7.62 X 39. I do not plan to or really want to start stamp collecting, so no SBR or cans involved.

What kinda ballistics are y'all REALLY getting out of a 16" barreled blackout?

Is it worth the trouble to build one considering what I already have?

Pretty sure the 300BLK beats both the 5.56 and 7.62x39 which was one of the stipulations of the creators of it. I would say if you're not planning to suppress it or SBR it, the 7.62x39 would probably be the way to go.

I echo this. Ammo is cheaper and easy to find.

If you WANT one that's a totally different matter, but there isn't a significant ballistic difference between the Blackout and the x39. The x39 has a little more case capacity and it follows that it pushes a similar projectile just a little faster, only it does it a lot cheaper. There are plenty of reasons to go with the Blackout over the x39 and vice-versa if you're starting from scratch... But if you aren't into stamp collecting and you already have a x39 that you like, then there isn't much reason to build a Blackout... unless you just WANT one.

Once I got a black out, I won't go back! It's freakin' awesome!

when you say ballistics, what do you mean- external (trajectory), internal (the actual case), or terminal (damage to the target) ballistics? There's lots of options when you say "ballistics".

Lol with what I said earlier, I'm in the process of buying the parts to build a 300BLK upper. It will be an SBR upper and suppressed, which is the reason I'm doing it.

what do you plan on doing with it?

Love my 300 Blackout. Softest shooting rifle I have and is a tack driver. Has killed hogs and deer alike with no problems.

Strictly hog hunting with it. Going to throw one of Primary Arms 1-6x scopes on it when the one calibrated for 300BLK comes out.

it's perfect for that.

OP what are you planning on doing w/ yours?

Cause 5.56 won't kill hogs?

I had to say it.

All data below has been tested at the range. YMMV

Supersonic

So, my cheap .300 BLK plinking load is as follows:

147gr FMJ M80 Surplus
15.6gr Alliant 2400
2.16" OAL
1900fps

This round has heavy recoil and it is a very hot load, from what I can find MOST supersonic velocities are around 2000-2100fps for 110gr projectiles, and I'm nearly there with a 147gr. I am the only one I can find that is using 2400 in the .300BLK, but it makes sense since it is a .44 magnum powder, which lobs 200-300gr projectiles out of a 8" barrel revolver. It only stands that 150-250gr projectiles out of a 9.5" barrel is going to be comparable. This load is extremely accurate (.34" group at 50 yards with a 9.5" barrel). I would expect 2000fps+ from a 16" barrel. So far this is the most energy I've been able to deliver with a .300 BLK load. My converted .223 cases last 3-4 reloads before the primer pockets open up and I have to get the ball bearing out. The primers are flat, but not seamless flat. There is no denying this is a hot load.




110gr Sierra HP
20.0gr H110
1.975" COL
2100fps estimated

This is a standard supersonic low recoil hunting load.






125gr Nosler BT
19.5gr H110
2.013" OAL
2000fps estimated

This is a standard supersonic low recoil hunting load. H110 is the standard powder for supersonic loads.





Subsonic

Caliber: .300 BLK
Specific: Subsonic
Powder: Alliant 2400
COL: 2.135"

chrg........1.......2......3.......4.......5
7.0gr......739...777....702....852....737
7.9gr......817...953....865....808....813
8.1gr......959...846....891....904....824
8.5gr......<Keith shot my chronograph>

So as you can see this project remained unfinished. Of course the SD will get better as the charges increase, my estimation is around 10gr of 2400 you might have a decent subsonic load here. I will revisit this again and finish my table.

*** Update 11/27/12 - Pointless endeavor, unable to cycle action at such a low weight, a heavier bullet is required for longer dwell time to cycle action. The action will start to cycle around a 200gr projectile, anything below that is a waste of time




225gr Hornady BTHP Match
11.7gr AA1680
2.16" OAL
1100fps

AA1680 is the standard subsonic powder for .300BLK. This load is for a 9.5" SBR barrel, if you're loading for a 16" barrel you would drop down to around 11.2gr. For reference the sound barrier in DFW @ 600ft elevation relative is 1130fps.




220gr Nosler Partition SP
10.8 gr AA1680
2.10" OAL
1040fps

Thanks G...that's the info I was looking for, real world external ballistics.

Happy to pass the info along. My buddy CJ compiled that data over a couple trips to the range. All of those rounds were shot from a 9.5" barrel so you should have even better results from a longer barrel.

Chad: I'm sure there's a lot of temptation to wax esoteric about the nuances of the word ballistics in a discussion that amounts to Ford-Chevy, especially if you're a Ford guy and there's a Chevy guy in the mix... But the intent should be pretty clear. There isn't much difference in bullet performance, whether you're talking about internal, external or terminal orgasms (or whatever) between the .300 BO and the 7.62x39. You have a far greater selection of bullets available in .308 than .311 which is great for your paradigm and I'm sure someone could mount a reasonable (if myopic) argument based around relative ballistic coefficients, but from any practical standpoint the two are extremely similar and if you're just going to punch pigs with it, I don't see the practical advantage in paying over $1.00 per round. So, in summation, the .300 BO may be perfect for pig hunting, but the 7.62x39 is just as perfect and a lot cheaper.

EDIT:

All results from a 16" ARP Barrel with mid gas fired on a warm day in April over a Shooting Chrony Alpha:

Wolf / Herters 154 Gr. SP
Avg. 2130 fps

Prvi Partizan 123 Gr. SP
Avg. 2450 fps

Hornady 123 Gr. SST
Avg. 2250 fps

Sellier & Bellot 124 gr. SP
Avg. 2400 fps

All of the above are adequate for pigs, but I highly recommend the Hornady offering or, if your rifle will chamber them, the PPU soft points. In my opinion it's better to avoid bimetal jacketed bullets for hunting purposes, but they still kill pigs just fine.

100% agree. The 7.62x39 and 300 blkout are very similar. The x39 has a slight case capacity advantage over the blk out, which yields a little more speed. I'm pushing my 125's right at 2230 fps in the blk out. The 123's can be pushed faster in the x39. But the quality of the ammo is not near as good as the 300 blk out. Better brass, better powders, and much better than the steel cased ammo. Better materials means a little more price.

I don't consider the 7.62x39 as an option for me, since it's the main caliber for the AK-47, which is used against us. I can't support it. That's just me.


I wasn't going to say anything about the quote, but since I'm writing here, I'd mention it. The reloading data that GDuse gave is actually internal ballistics, not external. It's like going to a car dealership and saying I need to buy a car. There's lots of options, and each one is different.

I'm also curious why AA1680 is "the standard" subsonic powder for the 300 blk out. I tested it, and I didn't like it at all. It was very dirty, and didn't yield the accuracy I was looking for that other powders did.

I get 2350 FPS out of my AR 7.62 with "Mexican Match" ammo, and it shoots around 2 moa with my setup.

I pull the factory bullet outta steel Russian ammo and replace it with the Hornady 123 grain sp. I don't care about lost brass this way and its a lot less trouble than reloading brass.....I have about 46 cents a round in this stuff....not super cheap but not real pricey either.


Chad, I've been taught internal ballistics as applied to firearms is the study of what occurs up to the muzzle, ie internal to the casing, and interior of barrel.

External is the study of what occurs between the projectile exiting the muzzle and striking the target...

And terminal ballistics is the study of projectile behavior after it strikes its target...

That is why I considered velocity at the point where it crosses the chronograph to be a part of the external ballistic portion of the projectiles travel...