5.56NATO or 300BLK?

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Curious thoughts on AR-15 cartridge choice? If you want to suppress there’s not much choice, and while that’s tempting realistically it’s be years at which point I could buy a different upper so kinda a non issue. So why would you pick one or the other?
 
For me, it would depend if money was not an issue. If money is no issue, .300 blk out all the way. You have plenty of sub and super sonic ammo to find exactly what you need to fit the mission. If money is an object and had a lot of bearing on this project, then I’d go with 5.56. Strictly because of ammo cost.
 
Fair point, I just kinda wanted unbiased thoughts… I’m in eastern NC. I tend towards 300BLK, cause it’s slightly more expensive but much more energy given the rounds mass and size. Don’t figure on longer range engagements so good for protection and good for taking deer etc at shorter ranges. More of a SHTF gun/cartridge.
 
My vote goes to 5.56…

1) Plenty of ammo out there and it’s cheaper.

2) Still in use by the military and a good # of LE agencies. If S ever did HTF, having a weapon chambered for a cartridge used by the gov at fed/state/local levels should make finding ammo a bit easier.

3) If Uncle Sam decides to go with a different cartridge, there’ll be a lot of folks dumping 5.56 ammo, because they “gotta have the same thing the military uses” and you’ll probably be able to pick up ammo for a good deal.
 
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For limited range and if you can stock enough ammo or components 300BLK is pretty versatile. But, it depends on your configuration. If you go rifle barrel length, like 16" I'd stay with 5.56. for "pistol" length I'd go 300BLK.
But, you mentioned SHTF. Staying with 5.56 gives you a better chance of ammo resupply or battlefield pickup and interchangeability with others.
 
I normally grab my 300 blk over the 556. I think mainly because I like that it makes bigger holes...
 
I personally have avoided to scratch the itch for 300 blk, just trying to keep my ammo inventory to a couple of calibers. For sure, there are advantages and disadvantages to both if you consider all of the "value" points.
@Cole_McD runs both regularly and has a great assessment. Jump in Cole.
 
Is a subsonic 300blk more effective than 45acp? Slow and pointy seems less than optimal.
 
JimB said:
Is a subsonic 300blk more effective than 45acp? Slow and pointy seems less than optimal.
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Very limited experience here, but I've never killed a deer with 45acp. Most likely, because I've never hunted with one.

I did, however, kill a 200lb 6pt with a 187gr polymer (or whatever PNW uses) tipped 300blk sub.
 
I think it really depends on what you plan to do with it.

Is it an occasional shooter? Maybe just a hunting rig? 300 blk is probably a better choice.

Do you plan on shooting it a lot? Taking classes and really training on it? 556 is the clear choice.

Define your use case first then pick the cartridge that makes the most sense. For 90% of use cases, 5.56 will likely make the most sense though.
 
The correct answer, of course, is both.

5.56 is the standard. 300BLK is more of a specialty/novelty round. 5.56 is half the price or better.

If I didn’t reload, no way I’d shoot 300BLK, but even buying very well, 300BLK (subs or supers) run me about 30cpr. The majority of my 5.56 was purchased for less than 30cpr, so again huge cost delta.

As for performance, I like that 300BLK performs so well out of short barrels and I can change from high performance 110-125gr supers to silent 220gr subs with only the change of a mag.
 
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JimB said:
Is a subsonic 300blk more effective than 45acp? Slow and pointy seems less than optimal.
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Up close, my personal choice would be .45. However, at mid to long distance, the .300 has better BC for accuracy and much better choices in projectiles. So it really depends on the mission.
 
kcult said:
Very limited experience here, but I've never killed a deer with 45acp. Most likely, because I've never hunted with one.

I did, however, kill a 200lb 6pt with a 187gr polymer (or whatever PNW uses) tipped 300blk sub.
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If anyone said “more people hunt with 300blk than with 45acp” I would instantly believe them. For hunting, where the scenario is a single shot at 30-100 yards I think it makes sense. For personal defense at 0-10 yards I don’t know. Just seems like the same mass and same velocity with a bullet profile less effective than FMJ ball ammo.
 
Both are great. 5.56 if you want to shoot at intermediate ranges out to 600 yards. 300blk if your typical engagement distance is 100yds or less. 300blk supersonic makes a fantastic hunting round, with 110gr Hornady V-Max being a solid option for bullet choice for proper expansion. 300blk if you want a shorter barrel for CQB. I can reliably run an 8" 300blk barrel as a handy PDW setup, whereas 5.56 the shortest I'd personally go is an 11.5" barrel but I personally prefer the full 16" for velocity (others may differ). Ideally, have 5.56 as your main, but get an 8"ish 300blk upper for when the scenario says 300blk is better. IMO there are definitely good reasons why 300blk has caught on and it isn't just a novelty cartridge, but it's true that 5.56 is much more readily available.
 
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JimB said:
If anyone said “more people hunt with 300blk than with 45acp” I would instantly believe them. For hunting, where the scenario is a single shot at 30-100 yards I think it makes sense. For personal defense at 0-10 yards I don’t know. Just seems like the same mass and same velocity with a bullet profile less effective than FMJ ball ammo.
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A 200+ 300blk sub designed to expand will outperform .45 is ever scenerio because of it's spritzer bullet design. Its just a better projectile in nearly every way.
Not to mention a 300 blk sub will still defeat soft armor, as a side benefit.

There's also the issue of platform, .45 acp carbines aren't really that common, and ones that actually work are even less common.
 
Cole_McD said:
A 200+ 300blk sub designed to expand will outperform .45 is ever scenerio because of it's spritzer bullet design. Its just a better projectile in nearly every way.
Not to mention a 300 blk sub will still defeat soft armor, as a side benefit.

There's also the issue of platform, .45 acp carbines aren't really that common, and ones that actually work are even less common.
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I get the platform issue.
But you think that a spitzer that is “designed to expand” will outperform a hollow point of the same mass, same velocity, and larger diameter at 0-10 yards? I‘m not seeing it, the HP will always make a bigger hole, and the spitzer doesn’t generate the cavitation at sub velocities that they do at super.
I’d be happy to be proven wrong, I have a couple guns in 300blk, just not feelin it.
 
5.56

save up $200 and buy the .300 blk upper later.

if you are worried about the cost of a secod upper, you can't afford to feed a .300blk imo.

speaking from experience, not trying to be degrading. ive have the exact same performance on deer from barnes tsx ammo in both cartridges. they run 40 yards and lay down.
 
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300blk for suppressed subsonics from short barrel.

Everything else 5.56.

Hunting is the exception. 350 legend out to 200 yards, 6.5 grendel for anything longer.

300blk does one thing very well, everything else its mediocre.
 
Currently in the same predicament on choice of caliber, building a 10.3” upper and having a hard time deciding between the two calibers. A few years ago I would have said the obvious choice is 5.56 due to ammo costs, but ammo costs aren’t what they used to be nowadays.
 
If money was no issue, .300 all day.
 
BigWaylon said:
Huh?

Suppressed 5.56 is waaaaaaaaayyyyyy better than unsuppressed 5.56. 😉
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Can’t second this enough.

After shooting my unsuppressed 10.3 rig, then getting behind a 10.5 suppressed (thanks @BigWaylon ), I can tell you there is a world of difference.
 
Dale Gribble said:
Can’t second this enough.

After shooting my unsuppressed 10.3 rig, then getting behind a 10.5 suppressed (thanks @BigWaylon ), I can tell you there is a world of difference.
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Okay, they both suppress better than unsuppressed. So which round then?
 
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