I picked up the PDW Daniel Defense8.5 inch for my keep near by self defense weapon. I go on camping trips and spend a lot of time at the cabin which is in a secluded area. We seem to have some interesting criminal activity that is growing in the area. A LE response would be well over an hour if I needed help. I guess I can either take the DD PDW 8.5 with or opt for a larger 10.5 Mark 18 style in either 5.56 or .300. Where can I find true date of how the rounds compare when fired through barriers. I like that the 5.56 is everywhere and easy to find if we ever have a true grid down situation. But I will opt for the more rare .300 if it makes sense. Where would the max effective ballistic and trajectory range between the two be found? I want to run both at rifle speeds and avoid the subsonic stuff. My family doesn't shoot so I would be the lone defender. These armed home invasions with more than one bad guy are a very scary thing. We had many copper thefts in the area as well as daylight smash and grabs. I just want to be ready. If they have similar ballistics, I will opt for the more common 5.56. But if the .300 truly represents a huge improvement, I will go for it. I want the pistol style brace as to avoid having to unload and lock during transport. Thank you.

OP,

Sorry to hear about the rising crime in the area, seems to be everywhere these days.  I would buy a 300 BO right now, but ammo is no where to be found at a resonable price.  I saw some FMJ rounds the other day for $2 each.  That is speciality belted magnum prices just 18 months ago.

As much as I have thought about this, I am starting to believe the 300 BO, pistol, suppressed just may be the best PD set up now.   I have a PSA stripped lower just waiting for something to happen to it....

Saying you need to unload and lock during thrasnport, I assume you are in the northeast in a communist state....they could give two craps about you and your family members safety

I like .300bo, as much as running 7.62x39 or 6.5 Grendel thru an AR.
Still an expensive round to shoot now but the steel case stuff seems to run & group

I shoot less 5.56 than any of my variant calibers.

I probably have 10-12 mags for every caliber I shoot along with a backup bolt or bcg.
For .300bo, not an issue. Last I looked .300bo was still twice what comparable .223 runs but when steel case 9mm is 60 cents a round 95 cents for steel case .300bo isn’t unreasonable.

It’s a bad time to get into 300BO, but I love it out of short barrels.

I'm a bit lost on the question vs the first post.

Do you already have an 8.5" .300blk...or is it 5.56?  
Is it an SBR (only) or a pistol?

Or are you asking if .300blk will stick around?

FWIW:

300 isn't a question of "catching on" - it's a question of whether or not it continues to become more popular or stays where it is now.

SAAMI approval in January of 2011. It's ten years old, and there's MASSIVE aftermarket support. Noveske now has 300 rifles/barrels/uppers in use by some of the most elite warfighters in the world, and that never hurts a particular round in the popularity department. It's hard to find ammo for 300 because people buy it. I'd assume it's still behind 5.56/9/12GA but it's probably more popular than any other alternate caliber for the AR platform, including 6.5 and 6.8 - it's already "caught on"

As far as ballistics, to some degree it's the indian, not the arrow. Supers are good out to 5/600 M if you can use a dope card/know how to walk shots in. Subs out to 200 if you know what you're doing. With cheap subs you're not going to get the massive wound cavity you would out of a 45 ACP or 12GA, but a properly designed, well-placed sub will down any human-sized target - and will preserve your awareness.

300 in a PDW with a short suppressor is an ideal go-to.

Post is a bit difficult to follow.  

I will say, if I were being shot at by someone at 100 yards or less, and they were using a 16" BBL, I would be frightened by any weapon; as all would be serious and lethal - with 1-shot stop power.  But I'd be more worried by the opponent being armed with a 5.56 at that distance, than by 300 BO.  

If I were being fired at inside of 30 yards, by a < 10" BBL, then the power of 5.56 would be so compromised by the velocity loss, that .300 BO would be what I feared more.

In all cases, I would be more concerned about 6.5 Grendel, than either of the other two; in any barrel configuration and at any distance.

Lol, what a crock of

OP, you've asked a VERY open ended question, so I'm going to give you data to go over instead of gun rag BS.

https://www.ar15.com/forums/ar-15/Suppressed-5-56-SBR-Velocity-Tests-41-Factory-Loads-from-10-5-11-5-12-5-and-14-5-ALL-DONE-/16-714088/
http://www.300blktalk.com/forum/viewtopic.php?f=145&t=97188&sid=655f98635863953e283ab8ba6eb9e7bb
(ETA: Pay more attention to the minimum velocity thresholds than the barrel velocities and max yardage as those change)
https://www.hornadyle.com/
https://le.vistaoutdoor.com/

I have to ask why?
While I do agree that both would be horrible to get hit by......16" vs 16" at 100 yards, the 300 can be quite a bit more powerful than 5.56.

I don't think I would want to fire a 9" 6.5G.....is that too short for a can?

.308 is what you seek.

Short barrels, swapping between supersonic and subsonic, and having 2x or so the mass of 5.56 projectiles are all reasons to have one.

For regular old home defense type use - you're sorta just burning money.  You don't need it that short, or that quiet, and you DO want to have as big a stash of ammo as you can manage, for the long run.    That sort of rules out .300 at the moment if you have nothing and are looking at getting your first or only AR.

OP might be missing the bigger picture in comparing .300 with 6.5G, etc.

.300 is a short, fat, old-school intermediate round, somewhat between .30 carbine and 7.62x39, but closer to the latter.   6.5G is a few compromises for better external ballistics and long range performance over the 5.56.    They're apples and oranges.

Topic Moved

Catch on?

300BO exploded on the scene and took off like a rocket about 10 years ago.
It's plateaued now.
Adoption and support was quicker and wider than 6.8 or 6.5.

However, I only shoot it with subs.

Seriously.  Just WTF

OP your post is unreadable.

Consider using paragraphs and sentences that have have some kind of point.

300 blackout isn't going anywhere if that's what you tried to ask.

How has 6.5 "failed?"

My 300 bo barrel sits in my parts bin but my 6.5 and 5.56 SBRs are still kicking.

More powerful? The extra 1000fps does things in tissue that foot pounds of energy can’t explain.

Blackout is a military cartridge now.


It's not going anywhere

OP I think your time lines on cartridges and what is popular is all messed up

Pure velocity by itself does not a whole lot of extra damage.  In 5.56, it is usually the fragmentation (if we are talking M193) caused from said velocity (+2500-2700 fps) that causes all of the extra destruction.

Besides, what bullet are you referring to?  Because at a 100 yards, most 5.56 rounds are going no where near 1000 fps faster than most of the popular lightweight 300 blk rounds out there if both are being fired out of a 16" barrel.

Listed speeds:
110 gr Barnes Tac-TX loaded by Wilson Combat = 2400 fps out of a 16" barrel  (I have some of this ammo, both the Barnes load and Wilson Combat load)   https://shopwilsoncombat.com/300-BLK-110-gr-Barnes-TAC-TX-2400-FPS-16-Barrel-20_Box/productinfo/A300BLK-110-TACTX/
110 gr Hornady Black V-max = 2375 fps out of a 16" barrel (I have some of this ammo) https://www.hornady.com/ammunition/rifle/300-blackout-110-gr-v-max-black#!/
110 gr Nosler Varmageddon by loaded Underwood = 2400 fps out of a 16" barrel.   https://www.underwoodammo.com/300-aac-blackout-110-grain-varmageddon.html
115 gr Lehigh Defense Controlled Chaos by loaded Underwood = 2360 fps out of a 16" barrel (waiting for this to come back in stock at Underwood, although it is in stock at MidwayUSA right now for pretty high price...I passed on it when I ordered my Tailhook Mod 2 last week)  https://www.underwoodammo.com/300-aac-blackout-whisper-115-grain-controlled-chaos.html

Hot 55gr 5.56 might be 700 fps faster at the muzzle, and 600 fps faster at 100 yards.  
Some of the faster, heavy 75 and 77gr loads might be 300fps faster.....other a lot less.

You might have been thinking of the normal short barreled .300blk against a 16" 5.56.  It is rare that equal barrel lengths ever get compared between the two.

That was comparing M193 and 125gr which is listed at 2115fps from a 16” barrel.

I am not an energy transfer proponent, but things approaching 3000fps make wounds that things just over 2000fps don’t make.

300bo is not a "huge improvement" over 5.56, in many respects it's a downgrade.

6.5 and others have not "failed" just because they are not as popular as 5.56.

If you're picking cartridges strictly based on popularity, you should pick 5.56 for the foreseeable future.

5.56 is a poor choice in the barrel lengths you are discussing, which is one of the strengths of 300 Blk. I'd consider 11.5" a minimum for 5.56.

300 Blk ammo is almost impossible to find right now, so now isn't a good time to be starting it as a new caliber.

You have much bigger problems than choosing a cartridge.

I see.  
There are not many 125gr rounds that are used in .300blk outside of the Fiocchi loaded Hornady SST, which is listed at 2200fps out of a 16".

I think what you are actually comparing is M193, specifically above the 2500-2700 fragmentation threshold, vs other caliber FMJ'ish rounds which are not pushed fast enough to fragment.  That is something fairly unique to 5.56 FMJ, and becomes irrelevant when other calibers are using fragmenting (or expanding) ammo.

I’m trying to compare like for like. 5.56 expanding bullets also rip massive holes in things. If you want to compare calibers compare those. The 50gr TSX is a hell of a killer for instance.

I think it is always good to compare like for like as well.

That Barnes 50gr TSX is an awesome round, and if you are talking a fast 50gr (3275 fps), you might be at a 875 fps different at the muzzle if compared to a fast 110.  

Closest round would be the WC/Barnes 110gr Tac-Tx...2400 FPS out of a 16" barrel.  

50gr .224 caliber expanding round: 3275 fps at the muzzle (1191 ft/lbs).  2780 fps at 100 yards (857ft/lbs).
110gr .308 caliber expanding round: 2400 fps at the muzzle (1407 ft/lbs).  2116 fps at 100 yards (1094 ft/lbs).

I guess my point in all of this is that both of them are bad news to get hit by and that when comparing expanding vs expanding out of the same 16" barrel length, .300blk does more than hold its own...at least in closer ranges.  Where 5.56 starts to pull away is +200 yards when using heavy, high BC rounds like TMK's and to an extent, SMK's.

Not close to truth on this. Used by some unit that can do purchasing outside typical contracts doesnt make it a military cartridge.

The OP's post seemed pretty straightforward. If you want a short rifle with great ballistics for 100-150 yards then 300 blackout is an excellent choice with Barnes 110 grain TacTX. My preferred urban rifle is an 8" 300 blackout with a 7.5" suppressor using the aforementioned Barnes rounds. Shooting subs is a neat option, but not something I'd put my life on in a defensive role. Ive also got 10.5, 11.5, 12.5, 14.5, and 16" 556 guns. For a short rifle 300 Blackout is an excellent option. If you're wanting something that you can go out and blast 1000 rounds a month, then no, 300 blackout may not be a good fit, but I didnt see the OP mention that.
Yes you can stockpile cheap 855 or 193 for the 556, but I personally don't shoot much if any of that because the accuracy is crap.
For the OP's situation, I dont see the cost of 4 or 5 boxes of Barnes 110 TacTX being that unreasonable.
Personally I load Hornady 110 VMAX for regular shooting, Barnes TacTX is what I keep ready for serious situations, and Hornady Sub-X for subsonic shooting. I dont do mag dumps or shoot just for the sake of wasting ammo.
I adjusted the powder loads slightly so that the Hornady and Barnes are both POA/POI at 50 yards.

300Blk is more viable if you are a handloader, especially if you can trim and form cases from 223 brass.

What do you mean “failed”?

If you mean “will 300 BLK ever be one as common and cheap as 5.55 ammo”?  The answer to that is no, it won’t.

Every AR variant is a niche cartridge.  None of them will ever dethrone the 5.56 as far as availability and low price.  But none of these cartridges have “failed”.  

If you want cheap ammo, go with 5.56.  If you want niche performance, go with a variant.  And be prepared to either pay more or load your own.

But these statements about caribou’s variant rounds “failing” is just plain wrong.

Just go with 5.56 unless you are canning a subsonic 300.

300 BO in a 12 inch barrel will do you fine to 300 to 400 yards with a 110 grain bullet. If your thinking SHTF, most of your targets will be under 200 yards anyways. BUT, getting any ammo right now is a chore. Slim pickings. Your late in the game getting a new rifle and cartridge.

Umm..what?  The 300BO and 6.5 Grendel are as popular as ever.  The Grendel's popularity is still steadily growing.  

The .300BO is good supersonic but it's big advantage is shooting subsonic.  If you're going to go suppressed I'd say .300BO otherwise I'd go 5.56 but either one is plenty of pew for home defense.

6.5G has arguably plateaued and won't really gain much of anything for steam, from this point on. The 300BLK has the potential to go further, as it has limited military adoption but the G failed in that regard, which I think is what the OP is asking about.

6mm ARC is stealing the lunch of the G now too, so expect it to dwindle further. In the end it will be the same as the 6.8, an enthusiast round that failed to achieve widespread military adoption.

If military adoption was the template for the "success" of a cartridge then everything other than 5.56, 7.62x51, 9mm etc is a failure.

The Grendel's, as well as the 6.8SPC, popularity is primarily among hunters and to some degree, long distance shooters who don't want to use a larger platform.  The 6mm ARC is another in a long line of calibers that has popped up recently.  It's smaller lighter bullets means it will never compete with the Grendel or the SPC for hunting anything larger than varmints.  It's going to be at least 10 years before it gives any indication of longevity.  Until then it's a big maybe. The odds are definitely not in it's favor.

Everyone said The 6.8SPC would be the end of the Grendel but here we are with the Grendel leading the popularity race between the two by a good margin.  The 6.8SPC is a very good caliber and hasn't lost it's popularity.  It just hasn't grown in popularity as much as the 6.5.  The Grendel will continue to grow in popularity in it's area of expertise, which is primarily as a hunting cartridge.  

Obviously, like the .300BO and the 6.8SPC, the 6.5 Grendel offers a far more effective anti personnel option than the 5.56 for those inclined to use it as such.  Neither the 6.8SPC or 6.5 Grendel are going away any time soon.  The 6mm ARC....?

The Grendal doesn't appear to have as large of a following as the fans of it seem to perceive. Steel cased 6.5G sat on the shelves of my local Scheels for months, during the panic and slowly sold off. The 5.56, 300blk, 9mm, etc on the other hand flew off the shelves. Very few factory rifles are made in 6.5G, which arguably is where the popularity of the masses come from. Yes people put together AR15s but more shooters gravitated towards the factory offerings, especially the new shooters.

As I said in my post, both are niche rounds that have established themselves as enthusiast/hunting rounds and both will continue to exist in that realm. Neither truly has a huge margin of followers over the other and neither will go away but will continue to exist in a realm with no massive adoption in the LEO/Military world. The OP is probably not interested in the heavily modest gains of either 6.8 or 6.5G but rather in the MASS adoption of a round and seeing brass cased munitions become cheap/available. Both have plateaued and may flux in popularity as time goes, we're even seeing a recent resurgence in the 6.8 SPC world but it won't ever be to the same level as 300BLK.

If not for the panic, 300BLK was arguably getting rather low in price. Not 5.56 price but still hand over fist better than we are sitting today post panic. It is a far more popular round and has enjoyed military success, albeit modest. I say this as an individual that is not a huge fan of 300BLK either but if there were such a thing as "alternative caliber war" for the AR15, the 300BLK has won.

I'd say 300 is losing steam to 6.5 grendel/6mm arc & 7.62x39 given ammo cost/cheap wolf & more wide purpose calibers.
300 is just a niche round for <8-10" sbrs/pistols and suppressed, else an inferior choice to other calibers.

This is how I feel as well, I don't see 300blk growing much more.

I never could the get accuracy w/300BO supers I wanted and sold it all off.

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Get rid of the 8.5” 5.56 and get an 11.5” 5.56 and an 8-9 inch 300 blk

You won’t find barrier blind 556 ammo in today’s market unless you spend $3/round on m855a1 or mk318 on gunbroker.com.  With factory loaded ammo prices where they are, you might consider the 8.5-10.5” 300 blackout and make the investment in reloading equipment.  The real reason 300 blackout is here to stay is that it’s only a barrel change away from 556 in the ar platform.

Pre-corona I would probably say go 11.5”+ 5.56 and keep 300+ rounds of quality barrier blind 5.56/223 for a duty scenario, but I think all of the good stuff is gone at anything resembling economical vs. reloading now and isn’t coming back.  M193/m855 will be available, but you are looking at 80cpr for non-barrier blind and minimal, if any, fragmentation ammo out of an 11.5”.

ETA - 7.62x51 nato is also going to be available out there in factory loads like m80 and that will take care of some barrier concerns for $1/round.  I’d go with at least 16” barrel in 7.62N, but YMMV.

I converted a 9" .300 BLK pistol to a 12" 6.5 Grendel, and a 16" 300 BLK to a 16" 6.5 Grendel last year.  Why?  I was down to about less than 5 boxes of Hornady 110gr V-Max, and a couple boxes of Gorilla subs.   I had never stocked up deep, since I didn't much care for the chambering after using it for a couple years and finding it lackluster for hunting, and I didn't have any real need for what it could do subsonic, other than the giggle factor at the range when my can got out of jail. I do still have both .300 barrels and bolts if I want to go back (doubt it, but the promise of cheap steel .300 BLK if/when the supply situation improves could make it more of a possibility)

At that time I converted, I could (and did) stack deep (though late) in Wolf steel and Hornady AG and ELD-M.  With what I do and needed, the 6.5 made much more sense, even if ammo availability wasn't an issue.  No regrets on the switch, really enjoy shooting the Grendels, and can actually do so without worrying about getting more ammo, I've got thousands and thousands of rounds of ~$0.30 Wolf to plink with (and while struggling to do 3MOA on a good day, it's a fairly lethal round for being so cheap and FMJ).  Plus a decent supply of quality, 1MOA-ish brass loads to use for HD or hunting.  

But if I had to do it over again today, with all the 6.5 ammo dried up (and .300 ammo even more expensive and scarce than last year) and still needed something short and very lethal, I'd probably opt for a .308 SBR just based on current .308/7.62x51 ammo availability and price, and the fact that if S actually did HTF, I'd be a lot more likely to find .308 than either 6.5 or .300.  Which is why I'm seriously looking for a good 12.5 .308 barrel or complete upper for one of my current 18" or 20" .308 builds.

I should mention I'm also stacked real deep in 5.56 and have builds in various barrel lengths, and for strictly self-defense I have no problem with it, just not a big fan of hunting with it, but they'd be the last to go if I had to thin out my collection.

TL;DR: For the OP, get a .308 SBR/Pistol and solve all your problems.