300 Blackout or 556/223?

[Barnfixer]

If you had to choose one, what one would it be and why? I’d like to go down the AR rabbit hole a little further with one of these, don’t feel like messing with both. The 300 almost seems more tempting do to the subsonic/supersonic thing. But the other is more economical to shoot. Give me some insight with your knowledge and experience.

 

[45/30-06OKIE]

Well I'm at a fork in the road here cause I love how quiet subsonic 300blk is with a suppressor but 5.56 out of a 16in Rifle Gas AR isn't that bad to be honest and it packs a wallop with 77gr SMKs. And 300blk you basically have to reload for subs to be economical...

 

[jonnyc]

I have three of each. Why stop at just one?

 

[Ohen Cepel]

If you don't have a 5.56 Ar already, I would go that way.

300BLK is great if you have a suppressor; if not, it doesn't do much for me. I prefer it in a bolt gun though as it is much quieter in a closed action.

 

[orionengnr]

If you reload, .300BLK.
If you don't, then 5.56.

Actually, if you reload, then one of each...and x39 as well

 

[Anchorite]

I’ve had both. Currently sticking with 223/556.
I‘ll be adding a can to mine this year (hopefully). While I think the BO is a solution in search of a non-existent problem, I can do everything with the 223/556 that I can with the BO, except serious barrier penetration, maybe.

I can’t seem to find a compelling reason to go back to the BO. Not even short range hunting. But that’s me. I’d like to hear from others.
I might go 7.62x39 next.

 

[Mstafford88]

I have one of each. 5.56 SBR for battle and fun, 300BLK/supersonic for hunting option and reload both.

300blk is fun to shoot and with my loads, extremely accurate at 250yds or so.(that’s the farthest I’ve shot with it). But it’s not economical or as easy to load since I cut down/form the 223 brass.

2.23/556 is easier to load and easy to find components for.

It all depends on what you’re using it for.

 

[MarshallDodge]

I will always error on the side of velocity and don't own a 300 BO.

 

[AJC1]

Is this your only rifle or just a toy... a 223/556 is a good round. I don't feel like dealing with one ir multiple tax stamps so as cool as a 9" suppressed 300bo is I'll never own one. A 300hmmr uses exactly the same components if your hand loading but is more on the supersonic side. I'm currently building a 6x45 because I find it intriguing....

 

[Another_Kelley]

If you reload, .300BLK.
If you don't, then 5.56.

Actually, if you reload, then one of each...and x39 as well

That's it, in a nutshell. The 300BLK is a reloader's dream with a mind boggling number of appropriate powders and projectiles to play with... but honestly you 'need' both

 

[Barnfixer]

I do have both, it is addictive! I keep bouncing around on what one I should setup for more serious purposes (possibly coyote & varmint hunting) and the other for plinking.

 

[westernrover]

From what I understand, 300 BLK has a narrower use case than the hype.
300 is most suitable when a suppressed subsonic load is desired and a long-range option using only a mag change to supersonics is useful.
If only a subsonic load is to be used a suppressor, 300 is inferior to larger caliber loads with heavier bullets -- possibly even 9mm or 45 ACP. For a subsonic load, why limit it to 30 cal? The only reason is for quick-change back to a long-range option.
If going supersonic and above hearing-safe, the 223 performs better, and so does 6.5 Grendel, 6mm ARC etc.
So the only place I can see 300 being ideal is when both sub and supersonic are wanted without anything but a mag change.

Now this is what I've understood, but here is my dilemma:

Suppose I want a semi-auto gun that's suppressed and hearing safe. What's the ideal solution? It seems like pistol cartridges makes sense. A 45ACP will drive a heavy, large caliber bullet to nearly supersonic velocities, especially out of a longer barrel, so what's the need for a bigger case? The problem I see is that most PCC are blowback, which I hate. I tried a SIG MPX (9mm) and the reciprocating mass sucked. So what? MP5 or Kriss Vector? The HK is mostly unattainable and the Vector has its own weird recoil impulse (downward). The bottom line is the AR is not only a far better value, it's far better period. The only thing to like about the currently available PCC's is that they shoot cheap 9mm ammo. Otherwise, they suck. The brace rule did/could really jack up guns like the Vector and B&T too -- unlike the AR, they were never designed as rifles.

300 cannot be the best suppressed AR cartridge, unless you want to be able to switch to supersonics or just switch-out the upper for 223. Otherwise, larger caliber cartridges would seem to make more sense. But which one? 450 Bushmaster? I hate that it headspaces on the case mouth. 458 SOCOM? I don't know. This is something I don't know about.

FWIW, when faced with the question in the OP, I went 5.56x45, not because of the cheap ammo, but because of performance (without regard to a suppressor). If I understood the answer to suppressing to hearing-safe levels, I might do something different, but I don't think 300 BLK is the answer.

 

[someguy2800]

Varmint/target shooting = 223 loaded with 77 gr
Self defense/3 gun = 300 blackout loaded with 110 vmax

 

[Pivot Dr]

Get a Grendel as well!

 

[earlthegoat2]

I have nearly every commonly available AR cartridge upper….except 300 BLK. I have no intention of getting one either unless falls into my lap for real cheap.

I guess my reasoning is that since I have so many other AR cartridges, one or more of them will be better suited to the task (hunting) than 300.

I suppose if I had suppressors I may think differently.

 

[jmr40]

IMO unless you want to shoot suppressed the 300 BO does nothing for me. In fact, I don't see where any of the other cartridges that you can fit into an AR-15 platform offer enough advantage over 5.56/223 to be worth the trouble.

With an 8 twist barrel you can shoot pretty much any bullet from 50-80 gr. When you get to 75 gr and heavier 223 bullets they do about about anything you can do with the larger caliber AR-15 choices. The 6.5 Grendel is the only one that remotely interests me.

To have any real gains in performance you have to move to the AR-10 platform.

 

[Anchorite]

IMO unless you want to shoot suppressed the 300 BO does nothing for me. In fact, I don't see where any of the other cartridges that you can fit into an AR-15 platform offer enough advantage over 5.56/223 to be worth the trouble.

With an 8 twist barrel you can shoot pretty much any bullet from 50-80 gr. When you get to 75 gr and heavier 223 bullets they do about about anything you can do with the larger caliber AR-15 choices. The 6.5 Grendel is the only one that remotely interests me.

To have any real gains in performance you have to move to the AR-10 platform.

This. Well said, Sir.

 

[Legionnaire]

My opinion, worth what you paid for it: General use, 5.56/.223. Suppressed, 300 BO. Hunting, 6.5 Grendel. Steel at distance, 6 ARC.

 

[jmorris]

The only thing I use my 300 for is killing pigs at night, with the Barnes tax tx bullet ~2000fps. If I am shooting at paper the .223 beats it by good margin and if I want to shoot 200+ grain subsonic projectiles, I find the 45 acp a good and cheap choice...

I will admit, I probably wouldn’t have a 300 at all but I built a machine to convert .223 brass for a mfg in Dallas and wound up with a lifetime supply of brass by the time I was done with R&D.

 

[jmorris]

I do have both, it is addictive! I keep bouncing around on what one I should setup for more serious purposes (possibly coyote & varmint hunting) and the other for plinking.

If you already have both, you probably already know the .223 is the pick out of the two for that job.

 

[Barnfixer]

If you already have both, you probably already know the .223 is the pick out of the two for that job.

Yep, you’re right. I do enjoy shooting the 300 but looking for a way to justify it or make better use of it.

 

[jmorris]

I understand, I just find it easier to enjoy them for what they are and let others worry about justification.

 

[hso]

I’d like to go down the AR rabbit hole a little

Depends on what you will use it for.

Range plinker... 5.56 all day.

 

[doubleh]

I would say your choice depends on your use unless you just like to play with different calibers in an AR.

The largest animal I will ever shoot with an AR is a coyote so 223 is my choice. If you run across one that weight 40 lbs. here it a trophy sized animal. They have to work hard to stay fed so don't get fat at all. I find 223 perfectly adequate and not with super sized bullets. I use 60 grain Sierras although a Hornady does almost as well in mine because that is what I have found to give the best accuracy but I have seen them fall to a 40 grainer from a slow twist barrel.

 

[.308 Norma]

Yep, you’re right. I do enjoy shooting the 300 but looking for a way to justify it or make better use of it.

I understand, I just find it easier to enjoy them for what they are and let others worry about justification.

These days, "enjoyment" has kind of become "justification" enough for me to buy a gun. I too have finally decided to jump down the "AR rabbit hole," and the first one I'm going to get is going to be a 300 Blackout.
Why? Because our middle grandson showed up out here at the house on Thanksgiving with a 300 Blackout AR, and I enjoyed shooting it. It was a real blast! To me, it was a lot more fun to shoot than the few 5.56 ARs I've shot. Besides, as I've said before, I'm an avid handloader, and I do think a 300 Blackout would be fun to load for - probably a lot more fun than the .223 bolt (a "boat paddle" Ruger 77) I used to load for.