.556 vs 300BLK

[cwillour]

How long of a barrel? If I wanted to go <10", I would lean towards the .300blk simply due to the cartridge's efficiency in shorter barrels. With 16" barrels or an 18" 5.56 barrel and light-for-caliber bullets, the .300blk seems to hold an advantage to 300yds or so for medium game. OTOH, it's my understanding that the 75gr & 77gr bullets seem to bring the practical advantage back to the 5.56 as the range increases.

If you reload and are good with an 18" or longer barrel, I think the 6.5 Grendel looses little (if any) in terms of short-range performance, has good mid- to long-range ballistics for the case length, and has some excellent bullet options.

 

[jwh20]

If you hunt, supersonic .300 blk is better for large game, and legal in more states than 556 for deer.

Including Indiana starting next year as I understand the new deer hunting regulations. 5.56 still won't be legal but the 300BLK would make the grade due to being 30 cal.

 

[Yeah]

If you hunt, supersonic .300 blk is better for large game

That ain't even halfway true.

 

[tdkahn]

here's a good video about .300 Blackout vs 5.56.


http://youtu.be/tgKjbySsAik

 

[One Shot One Kill]

That ain't even halfway true.

	Muzzle Energy in ft-lbs.​
	16 inch	10/9 inch
55 Grain Fiocchi .223	873.29	813.42	6.86%
62 Grain M855	1227.22	857.5	30.13%
115 Grain 300 BLK	1391.95	1124.80	19.19%

Seems better to me, and thats not taking into account the larger wound channel.

 

[Woobie]

I don't know what weapon system m you're planning on using, but if you're talking about running an AR platform, and you're going to be carrying extra mags, then there's a versatility advantage with the 300 BLK. You can carry a mag or mags with 200 + grain subsonics that are whisper quiet and hit like a .45 ACP, and other mags with 110 grain or so supersonics that have similar energy to a 7.62 x 39, and hit quite a bit harder than a .556 ever could. Going from one to the other is as simple as a mag change. I think it could work very well in both those roles. The downside right now is ammo availability, but you ruled that out in the beginning, so... no cons in my mind.

 

[Broom_jm]

One is a suitable varmint cartridge and the other can be shot with relatively low noise. Neither is a good big game cartridge, unless specific rate-of-twist barrels are used.

The previous poster doesn't seem to grasp that if you're sighted in for the 200gr sub-sonic loads, the 110gr supersonic bullets won't shoot to the same POA.

Of all the posters, only Yeah seems to understand the terms "energy", "wound channel" and "hard-hitting".

The 300 AAC Blackout is designed to shoot large pills quietly. Anything else people talk about doing with it is mostly just that; talk. I guess it's cool to shoot quiet guns, though it has little appeal to me; I like guns that make noise and have some recoil. That's what guns should do. The 223/5.56 has some practical application as a 300 yard crow or prairie dog gun, or a 250 yard coyote gun. The lousy BC of the light-for-caliber bullets fired from the 300 Blackout, along with the velocity restriction created by the overly-fast rate-of-twist, reduces the effective range of that cartridge for varmints. This is the main thing most guys fail to grasp: The fast twist barrel needed to stabilize the heavies limits how fast you can drive the smaller bullets.

Finally, I can get excited about an accurate 300 yard varmint gun. I can't get excited about a 30 caliber rifle that isn't even as powerful as a 30/30.

 

[sgreen3]

One is a suitable varmint cartridge and the other can be shot with relatively low noise. Neither is a good big game cartridge, unless specific rate-of-twist barrels are used.

The previous poster doesn't seem to grasp that if you're sighted in for the 200gr sub-sonic loads, the 110gr supersonic bullets won't shoot to the same POA.

Of all the posters, only Yeah seems to understand the terms "energy", "wound channel" and "hard-hitting".

The 300 AAC Blackout is designed to shoot large pills quietly. Anything else people talk about doing with it is mostly just that; talk. I guess it's cool to shoot quiet guns, though it has little appeal to me; I like guns that make noise and have some recoil. That's what guns should do. The 223/5.56 has some practical application as a 300 yard crow or prairie dog gun, or a 250 yard coyote gun. The lousy BC of the light-for-caliber bullets fired from the 300 Blackout, along with the velocity restriction created by the overly-fast rate-of-twist, reduces the effective range of that cartridge for varmints. This is the main thing most guys fail to grasp: The fast twist barrel needed to stabilize the heavies limits how fast you can drive the smaller bullets.

Finally, I can get excited about an accurate 300 yard varmint gun. I can't get excited about a 30 caliber rifle that isn't even as powerful as a 30/30.

Very well said. For me Id take the .223/5.56, mostly because Ive shot it enough to be familiar with the round and the longer range it gives. The 300blk isn't really worth it to me if Im not going to suppress it.

 

[bmbutch]

Largely depends on:
1) What's general purpose? HD, CQB, Long Range Capable, Quiet when Suppressed, etc.,
2) I wouldn't be in the 300AAC game if I didn't reload, factory ammo expensive.
3) Do you like suppressors?

I own 5.56, 300AAC, & .308 Modern Sporting Rifles, they all do things better than each other. For me:
1) 300AAC is a blast subsonic, I love tinkering with reloading recipes, & for now, it gets lots of "Ooo, what's that @ the public range I frequent.
2) 5.56 is fun to shoot, less expensive to shoot, & brass can be converted to 300AAC
3) .308 just makes you feel Bad A%#, solid (not harsh) recoil, can go very long range, & also short range blasting. Haven't started reloading for this yet, but it's next reloading purchase.

As always, YMMV, in the end for me, it's what makes me "all giddy" at the range.

Happy Shooting

 

[Woobie]

One is a suitable varmint cartridge and the other can be shot with relatively low noise. Neither is a good big game cartridge, unless specific rate-of-twist barrels are used.

The previous poster doesn't seem to grasp that if you're sighted in for the 200gr sub-sonic loads, the 110gr supersonic bullets won't shoot to the same POA.

Of all the posters, only Yeah seems to understand the terms "energy", "wound channel" and "hard-hitting".

The 300 AAC Blackout is designed to shoot large pills quietly. Anything else people talk about doing with it is mostly just that; talk. I guess it's cool to shoot quiet guns, though it has little appeal to me; I like guns that make noise and have some recoil. That's what guns should do. The 223/5.56 has some practical application as a 300 yard crow or prairie dog gun, or a 250 yard coyote gun. The lousy BC of the light-for-caliber bullets fired from the 300 Blackout, along with the velocity restriction created by the overly-fast rate-of-twist, reduces the effective range of that cartridge for varmints. This is the main thing most guys fail to grasp: The fast twist barrel needed to stabilize the heavies limits how fast you can drive the smaller bullets.

Finally, I can get excited about an accurate 300 yard varmint gun. I can't get excited about a 30 caliber rifle that isn't even as powerful as a 30/30.

OK, here's the deal: the cartridge was designed to make such mag changes. If you're shooting the subs, from a design perspective, you're probably shooting the subs in a room, or at least inside 50 meters. At these ranges, there will be a POI (not POA) shift, but you're still going to be "minute of man." Think about who designed this for whom and for what purpose. They didn't care about coyotes and deer. They were designing a cartridge that could kill badguys close and quietly, and more effectively farther away than the 5.56. If you want to talk wound channel, look up the wound channel m855 creates. It's abysmal, and the guys who were the intended end users, are shooting that crap. If you want to talk b.c., there isn't a 30 cal bullet made with a worse b.c. than the SS109 projectile. If you want to talk velocity in terms of rate of twist, come on be serious. If we're discussing even 5.56, we're not in search of almighty velocity. We're shooting a gas gun, most likely with a 16" or even shorter barrel. 1:7 vs 1:9 twist isn't going to make enough difference for the target to complain one way or the other. If the OP wants to know strengths vs weaknesses of these cartridges, then lets give it to him, but lets be realistic about what the cartridge is designed to do. Both of these cartridges were designed for bureaucrats in the pentagon, and as such are the product of compromise. Neither will be a great deer round. The .223 is a good coyote round, especially with some of the ballistic tipped projectiles (which are not available to the military, gotta love a war where only one side has rules). The 7.62 x 35 (300 BLK) was designed to fit an m4 receiver and magazines, still be light weight enough when carrying 210+ rounds for miles and days, and kill people. (Try sticking your 30-30 in an AR mag, just sayin'.) In that role, it does what it's designed to do better than the 5.56. As very few of us have that purpose, other than defense of family and property, we sometimes allow the argument to wander into areas that are outside of the design of the cartridge(s), and we try to make it do something it was never going to do well, then impugn it for sucking in its new role.

 

[Indyfishyak]

+1 on the 6.5 Grendel better ballistics and slight edge on wind drift. Con is as of 2014 not a legal deer round due to caliber but may change in 2015. Could also load heavier bullets to compete with 300 subsonic advantage

 

[Broom_jm]

OK, here's the deal: the cartridge was designed to make such mag changes. If you're shooting the subs, from a design perspective, you're probably shooting the subs in a room, or at least inside 50 meters. At these ranges, there will be a POI (not POA) shift, but you're still going to be "minute of man." Think about who designed this for whom and for what purpose. They didn't care about coyotes and deer. They were designing a cartridge that could kill badguys close and quietly, and more effectively farther away than the 5.56. If you want to talk wound channel, look up the wound channel m855 creates. It's abysmal, and the guys who were the intended end users, are shooting that crap. If you want to talk b.c., there isn't a 30 cal bullet made with a worse b.c. than the SS109 projectile. If you want to talk velocity in terms of rate of twist, come on be serious. If we're discussing even 5.56, we're not in search of almighty velocity. We're shooting a gas gun, most likely with a 16" or even shorter barrel. 1:7 vs 1:9 twist isn't going to make enough difference for the target to complain one way or the other. If the OP wants to know strengths vs weaknesses of these cartridges, then lets give it to him, but lets be realistic about what the cartridge is designed to do. Both of these cartridges were designed for bureaucrats in the pentagon, and as such are the product of compromise. Neither will be a great deer round. The .223 is a good coyote round, especially with some of the ballistic tipped projectiles (which are not available to the military, gotta love a war where only one side has rules). The 7.62 x 35 (300 BLK) was designed to fit an m4 receiver and magazines, still be light weight enough when carrying 210+ rounds for miles and days, and kill people. (Try sticking your 30-30 in an AR mag, just sayin'.) In that role, it does what it's designed to do better than the 5.56. As very few of us have that purpose, other than defense of family and property, we sometimes allow the argument to wander into areas that are outside of the design of the cartridge(s), and we try to make it do something it was never going to do well, then impugn it for sucking in its new role.

Do you have any proof of the above two statements in bold? From what I've read, you are making assumptions based on facts not in evidence...in other words, you're dead wrong. The 300 was designed for shooting at far greater distances than 50 meters, but not be easily identified as the source. The wound channel of the 5.56 is a function of the bullet it fires, not the MV or energy. Blame the Geneva Convention, not the cartridge.

As for the statement in red, I presume you've never heard of the Remington 30 AR, which does approximate 30/30 ballistics from a cartridge that IS fed from an AR magazine. For absolutely everything except shooting suppressed, it is superior to the 300 AAC Blackout. The simple reality here is that the 300 does suck at everything other than shooting suppressed. The numbers don't lie.

I think the 300 is COOL...I really do, but it has very little practical purpose. It is meant to kill people, at distance, without being noticed as the gun doing the killing. The idea precedes the current 300 AAC Blackout cartridge by at least 30 years (see 300 Whisper) and aside from being able to shoot the sub-sonic stuff w/o ear protection, I see little to recommend it over other designs. Once again, the very fast twist rate in the barrel makes it a one-trick pony, but apparently all the tacti-cool guys can't wrap their head around that annoying little fact.

 

[ckcollins2003]

I think the biggest question is, "What are you going to use it for?"

Do you plan on hunting? Do you plan on keeping it as a home defense gun? Or do you just want something new to shoot paper with? Either way, pick whichever one you want more. Both are going to kill animals without hesitation. Both are going to kill humans without hesitation. And both are going to put holes in paper without hesitation.

Quite personally, I don't see the point in using a 5.56 or a .300 AAC for late night burglar killing while your family is in the house. I'd hate to see a family member killed by a bullet that went through 4-6 walls all because I missed and thought it was a good idea to try to be "Mr. I have the bigger gun so **** you"... but again, that's just my opinion.

Pick whichever one you want more. This is like the 9 vs 45 debate... when it comes down to it, it doesn't really matter.

 

[shibumiseeker]

Once again, the very fast twist rate in the barrel makes it a one-trick pony, but apparently all the tacti-cool guys can't wrap their head around that annoying little fact.

I know you're on a crusade against the 300BLK, but I have never considered myself tacti-cool and I really like the round, for reasons I have often enumerated here, none of which have anything to do with being tacticool, and as far as I am concerned putting it through a suppressor is low on my list of reasons I like it, though that is pretty cool.

 

[Broom_jm]

I know you're on a crusade against the 300BLK, but I have never considered myself tacti-cool and I really like the round, for reasons I have often enumerated here, none of which have anything to do with being tacticool, and as far as I am concerned putting it through a suppressor is low on my list of reasons I like it, though that is pretty cool.

I just got done saying, "I think the 300 is cool...", so I'm not sure how you can say I'm on a crusade against it. I'm a huge fan of the 44/40, but I don't expect everyone to like it as much as I do.

 

[shibumiseeker]

I just got done saying, "I think the 300 is cool...", so I'm not sure how you can say I'm on a crusade against it. I'm a huge fan of the 44/40, but I don't expect everyone to like it as much as I do.

Because you've spent a lot of time arguing against it. Again and again and again. While some of your points have validity the amount of effort you've put forth to harsh folk's buzz has the whiff of crusade. Normally you give pretty good advice and conversation, at least that I've observed over the years, but this topic carries a different flavor.

 

[Broom_jm]

Because you've spent a lot of time arguing against it. Again and again and again. While some of your points have validity the amount of effort you've put forth to harsh folk's buzz has the whiff of crusade. Normally you give pretty good advice and conversation, at least that I've observed over the years, but this topic carries a different flavor.

Maybe you're right...maybe I shouldn't voice my opinion on it, since I'm in the minority. Maybe nobody should ever say anything unless they are just nodding their heads and agreeing with what the masses think. That's what made this country great, right? Why should we have opinions, or voice them, when everything would be much more harmonious if we all just agreed on absolutely everything.

The 300BLK is the greatest cartridge ever conceived! It is superior to the 5.56 in every possible way and I can't understand why gun and ammo manufacturers would build for ANY other cartridge!

Better?

 

[shibumiseeker]

deleted. Nevermind, I'll stop now.

 

[cop car]

Everyone should have a 14.5-20in barreled 5.56 AR15. People hate on 5.56 but it is the best thing that has happened to firearms since John Browning.

once you have one, then you can start looking at other calibers. 300 blackout was designed to be ballistically similar to the 7.62x39, and it does a good job of it. It is not a long distance caliber (not that great beyond 300yards) and a loaded mag is significantly heavier.

300 AAC BLACKOUT (300BLK)

 

[Robjps]

DISCLAIMER: for the purpose of this discussion, cost and availability are not an issue. You have a billion rounds of each to choose from...

When does the 556 outshine the 300BLK? What are the pros and cons of each (keep in mind cost and availability are not a factor)?

.556 pros
Shoots flatter than 300BLK

.556 cons
Not deer legal in Indiana

300BLK pros
Able to shoot subsonic
Better for game hunting

300BLK cons

300blk is nice to suppress where its like shooting 45acp 230grain ball. That's it just a cheap way to get to get subsonic in the ar platform with just a barrel switch. It does do better then 45acp at longer range due to better bullet design BTHP.

If i can only have one rifle 5.56, but if price is truly no option i would have both 300blk suppressed with NVG and IR laser would be hella fun to train with.