Hi All,

I'm really pulling my hair out deciding on a pistol upper.  In every sense for me, 300BO is the right choice (Home/work/car defense).  But, my budget is shit.  I'm already heavily invested in 223 ammo and only have one 223 AR as is.  I wanted a second 223 to keep shit simple and budget friendly.

But less that 12" or so, 223 kinda loses all that advantage.  And since I have a 14.5" already... why add another similar length gun.

So, since I really think an 8.5" or 9" 300BO would be the best for defense.  I am tempted to go that route.  

Also, I want a can to match either.  That is waaay down the road due to budget.

So, I guess I'm asking... Does it make sense to build the 300BO for HD and buy a mag or two worth of ammo for now?  

The subsonic part.... Since I won't have a suppressor for some time .. if ever, what is subsonic like for HD without suppression?

Thanks for the insight, regards

I have AR15's in 5.56 in most lengths from 11.5 to 24.  I like my 11.5 pistol, but it pales in enjoyment and use to my 9.5 300BO pistol.  Now, mine is used mainly in suppressed mode, but you can just as easily shoot supers in the 100-130g range.  Nothing wrong with 5.56 pistols, but IMO you really gain a more useful firearm in pistol length with the 300BO, especially if you have other 5.56 AR's.  If you're going to get a suppressor down the road, it makes a 300BO an even better option.

Subs will work fine for HD.I put one together for my brother two weeks ago and so far it has been perfect through right at 400 rounds.
100 of them were subs.This is his.
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I've shot .223 in 7.5 and 10.5 barrel lengths and to me even the non-sub don't have the concussion of the .223.
I'm just waiting for my upper to get here to finish my .300.Hopfully tomorrow or Monday.
Here's my lower.

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What's the weight of the maxim brace system?

The powder is burned up in the shorter barrels, another of the benefits of the .300 Blackout

Short barrel, suppressed is where the Blackout shines, but, it still have some usefulness even unsuppressed.

Mine is the SB Tactical and their website says it's 18.14.ozs.
I haven't weighed it personally.

Eta: from what I've been able to find on a couple other sites it weighs the same at 18.14.ozs.

Should have put this in my first post but if you want a nice 300BO this one is 219.00 and to add the BCG and charging handle is 99.00 more.
This is the place my brother and me got ours from.
Ghost Firearms

I'm a noob in the field of AR pistols, though I have a couple...

what is the advantage of a .300BO subsonic?... what advantage does a 140grain .308" projectile at 1050fps have over a 147 .355" projectile at 1050fps?

I was just thinking about my hearing if I had to use it indoors.

300bo sub would be 200-220 grain but you have a valid point.  9mm ammo is a lot cheaper.

Any  762x39 in sub?

This is all I could really find with a quick search.
It Ain't cheap either.

7.62x39 subs

For some reason it won't load to the page directly you have to scroll down to the bottom.

I'm getting a little outside my knowledge envelope here, but I think the advantage of subsonic 300BO recommended in the 200-220g is range and energy over a subsonic 9mm.  Isn't that the case?  Bullet drop and energy delivered along the bullet flight path is greater with a 200-220g bullet over a subsonic 147g 9mm if I understand correctly.  Anyone clarify this?

Energy (at least in this scenario) really doesn't play a large part in wounding.  Velocities are low enough that you're not getting much, if any, stretch cavity, so there's nothing gained there.  You're essentially relying on the bullet poking a large enough hole (which is pretty much restricted to the diameter of the bullet, unless you're using an expanding projectile) to do damage.  Even if energy was playing a part, .45 is still cheaper than subsonic .300BLK, and velocities and weights (and therefore, energy) are very similar between the two.

As for better ballistics, not really.  Even something like the subsonic 208gr AMAX load from Hornady (the 208gr AMAX projectile has a decently high BC) has a stupid amount of drop outside of 150ish yards when zeroed at 100.  Running the numbers through Strelok, comparing the 208gr AMAX loading to the 147gr XTP and 230gr XTP, all at 1050fps and zeroed at 100, they're all within an inch of one another out to 150y and within a few inches at 200y.  

Honestly (and this is my opinion, so it's worth what you paid for it), subsonic .300BLK does nothing better (at least ballistically speaking) than a subsonic PCC.  Now, where the Blackout does rein king is in the ability to switch to supers, which are going to be ballistically superior to pretty much any pistol cartridge.

As to OPs question, my recommendation would be to spring for a 10.5" 5.56/.223 upper and splurge on some quality factory expanding ammunition (like Fusion, Gold Dot, etc.).  Even with the slower velocities 5.56 reaches out of a 10.5" barrel, you'll still have a couple hundred yards inside the expansion envelope of most quality defensive loadings.  You also have a bunch of .223 stockpiled already, so that lowers your ammunition costs for practice (arguable the most important part of employing any firearm in an offensive/defensive capacity), and to top it off, quality 5.56/.223 defensive loadings are significantly cheaper than their .300BLK counterparts.

If budget is as large of a concern as it seems to be in your case, OP, I think 5.56/.223 is easily the smarter choice, even if you have to deal with a 1"-2" longer barrel.

RJeff21, but isn't bullet drop within that 100 yards markedly worse for 9mm subsonic?  In my reloaded 300BO with those 208g ELD-M's subsonic with the suppressor, I can confirm that 3-3.5" drop at 100 yards that most ballistic charts show.  It goes to heck fast after that.  I don't personally load 9mm in supers or subs, but most of the charts I see seem to show 10" and more drop at 100 yards.  .45 ACP seems to be the same or worse.  One thing I'll guarantee with 300BO subsonic through a good barrel around 9" in length...within the 100 yard envelope, it's a very accurate setup.  I have a pair of 16" 9mm carbines, and they will shoot decently to 100 yards, but that's a rifle barrel with 115g and 124g +P level ammo.

How far you're dropping at 100y is really going to depend on zero distance.  You have to make sure zero distance is the same between the .300BLK subs and whatever PC subs you're comparing or the drops are going to be way different.  Comparing your numbers for drop on your .300BLK rifle and just a generic chart for the drop out of a 9mm pistol is not going to tell you anything.  

ETA:  And to be honest, I'm not even sure 100y would be a good zero distance for a subsonic pistol cartridge.  Never really looked at it or thought about it.  I'd imagine your hold under (with either setup, honestly) between 25-75 would be pretty large.

Here's a comparison. I've now changed the zero distance to 50yd if you want to talk about a "100y and in" rifle.

147gr XTP @ 1050fps:
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208gr AMAX @ 1050fps:
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Things start getting more lopsided towards the AMAX once you get past 150y, but then again, who's trying to use subsonic anything past 150y in any type of serious situation in the first place?

ETA2:  Just for shits and giggles, here's a drop chart for a 230gr Gold Dot @ 1050fps.  Still, roughly within an inch of the AMAX at 100y.

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I'm guessing the much higher ballistic coefficient of the 300 plays into this.

BC and hold over aside, I do know that the 194g ME subs recovered through water jugs shot from my 8" 300 are nearly double the size of my recovered 9mm HST's shot with my G19.

While I'm sure the LD 194gr ME is a great projectile for the platform, it's one projectile.  It costs a shit ton (comparatively).  

My point is, when it comes to doing this on a budget, choosing the platform that will give you the most quality options at the lowest price point is going to be the smart move.  OP is talking about building this thing to use in a defensive capacity and then only purchasing a few mags worth of ammo for it.  No offense intended, but that's fucking retarded.  When you can only afford to buy a few boxes (if that, since the LD stuff is $2/round) of quality defensive ammo, it's probably best to pick something with less expensive ammo costs (especially when you should be practicing with the thing you may depend on in a serious situation).

If you're wanting subsonic, 9mm or .45 is going to be a lot more budget friendly (both for practice as well as defensive loads) and is going to give you performance that is very similar.  Expansion tests I'm seeing for modern quality 9mm and .45 JHP loadings show an average expansion diameter of .6"-.75" and .8"-1.0" respectively.  Lehigh Defense claims an average of 1.2" expansion diameter for the 194gr ME.  All more than adequate for defensive purposes.  

With that said, I say all this as a guy who just built an 8.3" .300BLK rifle and has no plans for a PCC anywhere in the future.  Maybe I'm just crazy (although I do plan to use supers for anything that requires killing stuff).  

I still say in OPs case he's better off with a shorty 5.56/.223 upper.  He says he already has ammo, so you don't have to factor in that cost (unless he wants to pick up some quality defensive loads).  If he's worried about concussion, use a linear brake to redirect some of the sound forward.  My hearing is the last thing I'd be worried about in a life or death situation anyway.

Subsonic 300BLK is about as good as a 9mm or 45acp. Not nearly as good as the supersonic 300BLK or 5.56mm. Pistol rounds vs. Rifle rounds basically. If it's not going to be suppressed, then I'd much rather go supersonic rifle rounds. Honestly while subsonic suppressed is impressively quiet, I still much prefer supersonic rifle rounds suppressed for home defense. It's just much more lethal, and it's not like you're on a super stealth mission or anything, haha

Thanks for the replies.  It seems the more I learn the more indecisive I am on coming to a conclusion.

I was really buying into the 300BO hype, but it seems a lot of what I'm reading states it really isn't that superior.  I keep my G-19 and/ or 870 by my bed.  The longest HD shot I would ever have to take would be well within 10 yards.  I guess all the AR>12g threads got me thinking.

At the end of the day, I have two arguments for a pistol build.  One, is that, if built first, I can switch back and forth with no legal concerns.  This can be satisfied if I just go ahead and purchase a brace, use it, then whatever.  Two, I was thinking a car gun.  Something that could reach out 100 yards max if needed.  I can legally carry a pistol, but not keep a long gun ready in a vehicle.

Thanks again

slightly more expensive option followed by a friend and myself is to build a 5.56 10.3" pistol (I have a 7.5" upper also), and add a LAW folding stock adapter to the pistol...the adapter adds approximately 1", so a carbine length pistol tube without any blade or brace works well for me.. there is no release button needed to make the pistol operational

The AR>12 gauge threads are not wrong, that information is just dependent upon using the correct caliber/ammunition.  You will be infinitely better served by a 5.56/.223 shorty upper or even a .300BLK shorty upper provided you use supersonic ammunition, especially when you factor in your desire for a truck gun that's capable at 100yds.  You won't be bringing much effective fire to the table at 50y, let alone 100y, with a G19.

My new house gun is a PSA 300 BLK pistol. The subsonic ammo is much quieter and less recoil than the supersonic rounds. With my red dot sight I feel I have a better weapon than a handgun. I can easily put a mag of supers in the pistol in an instant if need be. The PSA pistol was $499 shipped and has been perfect so far.

What ammo are you using?

I guess I don't understand why you're limiting your ammo selection to subs. If you're not using a silencer, then you aren't really going to notice an audible difference between subs and supers, at least enough of a difference to matter - neither are close to hearing safe - and especially in a self defense situation, where you'll likely be so full of adrenaline and focused on the threat that you don't notice the loudness of your shots either way. Why on earth would you use subs then? Even with a silencer, the increased loudness of supers is a welcome trade off for the increased lethality. My 7" 300blk is still more or less hearing safe with supers (probably not a good idea to do a lot of shooting indoors without earpro, but out in the desert it doesn't bother me at all). Subs are quietER, but if your/your family's life is on the line, why handicap yourself for a few decibels? Without a silencer, the desire to use subs makes even less sense.

Once you bring supers back to the table, the AR>shotgun comes back into play. With 110gr Barnes you've got 30+1 rounds that offer better ballistics out of an 8" barrel than 223 will ever give you from such a short barrel, with all of the benefits of a short, quick rifle. 

The other great thing about this is that if you wanted to use subs for some reason (there is literally no reason unless you're running a can), you can just shoot subs and switch back and forth with no modifications or adjustments. 

But yeah, you seem to have misunderstood the 300blk "hype" if you're only looking at subsonic ammo without a can for self defense. If you only ever wanted to use subsonic ammo, then a 9mm MPX or something makes a lot more sense, since you're getting similar capabilities for a lot less per round. But with an MPX, or any pistol caliber carbine, you DON'T have the option to switch mags and instantly have access to rifle-class ballistics. 

Good stuff. I too had the idea of getting a 300 Blackout pistol and running subs through it unsuppressed until I was able to get a silencer. I had no idea that balistically, this isn't really a good idea. I was basing everything off of the idea that shooting indoors would suck, but would suck less running 300 Blackout subs unsuppressed compared to a 5.56 unsuppressed. I mean, I think it would still suck less, but if the ballistics aren't there to back it up, what's the point?

So can someone explain a bit more - does running 300 Blackout subs through a suppressor increase the ballistics a bit, or is it still a better idea to just run supersonic ammo?

From a terminal ballistics standpoint, there isn't much, if any difference between .300BLK subs (with a suppressor or not) and a 9mm or .45.  There are a couple subsonic expanding .300BLK projectiles available now, but they're all extremely expensive (prohibitively so, if you are on a budget and want to stockpile a decent quantity) and offer extremely marginal improvement over modern pistol caliber JHPs.

To be honest, the sound difference between a PCC and a rifle aren't all that big in practical application, especially when your life is on the line.

.300BLK is a fine cartridge, but IMO, it's better to stick with supers for social purposes and it's more cost effective to choose a PCC if subs are a must for you.

The first 6 rounds in my 8" HD magazine are 194g ME subs, and the rest are 115G CC supers. My spare magazine is loaded with all 110g Barnes tac-tx supers.

If the 1st 6 rounds of the subs aren't enough, then hearing damage is the least of my worries.

194G ME:

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Is supersonic 300BO from an 8" barrel better than supersonic 223 from an 11.5" barrel?   That is where I am right now.  

If so, I am game for the 300.  It will honestly be years before I can get a suppressor anyway.  I have electronic ears I can keep by the bed anyway...

Comparing something like the Barnes 110gr TAC-TX to a quality expanding 5.56/.223 load?  I'd say the .300 would be better.  You're getting rifle velocities, which is exponentially better for wounding capability, on top of the projectile itself expanding to a much larger diameter than the 5.56/.223.

Now, you also have to factor in the ammo (both practice as well as "serious use") costing 2x-3x as much.

With all that said, for someone on a budget who also has a decent stockpile of 5.56/.223 ammo, I think a 10.5" 5.56 upper is a much better idea.

While that may work at HD distances, if shooting to 100+ yards is a foreseeable situation for your intended usage, it's not anywhere near ideal.

The trajectories of a 110gr supersonic load and a 194gr subsonic load are worlds apart.

According to this comparison chart that has been floating around for years, 8" 110g blk will give you the same energy as a 12.5" 5.56, but with a larger diameter hole. 

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Of course, hence the 'HD' in the first sentence of my post, and I thought that is what the OP was asking about.

Not sure how this thread got sidetracked into longer range shooting.

If comparing SD rounds of equal quality, IMO, yes.

OP has clearly stated throughout this thread that "truck gun" is a capacity that he wishes to fill.

If you're going to get a can, get a BO.
The 556 is cheaper to run.  I like both.

That is an unequivocal 'Yes.'

Also, auditory exclusion in the heat of battle will most likely make your hearing concerns a moot point.

Go shoot some meat at HD range with some subsonic ammo. It doesn't expand at all. It usually just ice picks and keeps on going. Yes I know from real world experience and not regurgitating from the internet.

I'm looking at an 11.5" 223 right now.  I see they make muzzle devices that keep the blast forward.  I think this is a decent starting point.

Thanks All

"Keep the blast forward" probably sounds to you like it will help more than it actually will. I had a7" 5.56 with a flaming pig, and it was just as loud as it was with an a2 hider. The only difference was that people standing to the side of me didn't feel concussed. 

It sounds like you're trying to get as close to the benefits of a suppressed weapon as possible without actually using a suppressor. What you will learn is that there suppressed, and there is unsuppressed, and it isn't a spectrum. No mixture of subsonic ammo or muzzle device is going to make any difference to your hearing from a center-fire gun. Anything unsuppressed is going to be unbearably loud in normal circumstances, and in those auditory exclusion moments, it would not matter if you were shooting a subsonic 9mm or a 44 Magnum or an SBR 308. You won't notice how loud it is, but you'll suffer the same hearing loss. 

Since this thread started, I've been trying to research this original question a good deal.  The problem is that most data I find doesn't give a good apples-to-apples comparison between 300BO, .45, and 9mm subsonics...or...it doesn't provide enough detail to come to a good conclusion.

What material I have gone over, however, still indicates to me that the 300BO should still be superior up to and at the 100 yard mark.  When I can find bullet drop data, it usually indicates more drop for .45 and 9mm subs.  300BO seems to hover between 3"-6" in subsonic.  Being a reloader I can see one fairly big component of the Blackout that would assist it...far superior bullet BC.  As most 9mm and .45 subs go down range, they lose a lot of steam just because of their generally bad BC characteristics.  A 208g-220g AMAX or ELD pushed at the same speed allows less energy to be bled off within that 100 yard range.  This isn't important for MP5 house clearing duties, but that's not what we're talking about if I understood correctly.

Again...I claim no expert status here.  Exacting data on this was hard for me to find, and I certainly didn't find it.  Lots of opinions and such, and even some info that appeared quite good, but then they didn't list barrel length and other critical factors.  This is the pistol forum, and pistol length is what we were talking about originally.  Surely someone has performed an equal-to-equal test against 300BO with at least one of these pistol calibers in subsonic mode.  If you find it, please link it.

Ok, let me pare this down a little more.

How effective is 55g/ 62g .223 from a 10.5" barrel at 20'?  .... compared to 12g 00buck...

(I want 11.5" but 10.5" barrels are everywhere... and I really like the Aero upper).

You keep on referencing this "drop data" without ever actually citing the source, so I can't help you there.

Not to mention that I actually provided you with ballistic drop charts comparing one of the best subsonic loads (BC wise) to your average pistol projectiles.  Those are all using data direct from their manufacturer's websites, it's all correct and the numbers don't lie.

As for barrel length and stuff like that, it doesn't matter as we're talking about subsonic loads.  Barrel length only matters in the sense that velocities typically go up with longer barrels.  We're limiting ourselves to a specific velocity, regardless of barrel length, though, so it's not really important as far as this discussion is concerned.

Also, since terminal ballistics is a component that needs to be examined in this equation, those AMAX and ELD projectiles aren't going to do anything but poke holes at such low velocities, whereas pretty much every pistol caliber JHP projo is going to reliably expand.

Very.  Once again, projectiles traveling at rifle velocities cause a lot more damage than projectiles traveling at pistol velocities (although, lots of pistol projectiles at the same time can make up for that).  You're also missing that there are a lot of quality defensive loads in 5.56/.223 that work great at SBR velocities and will continue working out to a couple hundred yards.

You also have to factor in the AR being a more compact package, lighter weight, easier to reload, larger capacity, exponentially larger range, etc, etc.

Based on your original "wants" in this thread, a 10.5" AR pistol makes the most sense, IMO.

Awesome. Thank you

Speaking as to what loads to use in a SBR/Pistol, here are a few good choices at good prices.

64gr Gold Dot @ $0.50/round
62gr MSR @ $0.77/round
75gr TAP SBR @ $0.70/round

There are a bunch of other if you look in the "ammo" section here in the AR forum.

The 200+ gr subsonic.300blk loads have better ballistic coefficients so they will resist wind and drop less at longer distances. If you have a .223/5.56 ar all you need is an upper. 220gr at 1050fps has more energy than a 147 or 165gr bullet at the same speed.

I was on the fence about my next build and decided on 300blk over 9mm because of initial cost.  After the blackout build 9mm is high on my want list. It might be after a 45-70 or .450 bushmaster for suppressed deer hunting though.

How's this look for an HD set up?  Any issues with a chrome moly barrel?

DSG complete

Looks good.  I've heard some decent things about those DSG "duty grade" uppers.  CMV barrels are pretty much the standard when it comes to ARs, so yeah, they're fine.

I love my 7.5 for HD. I don't know about anybody else but , 30 rds of any 223/556 at 0-75 yards is going to be enough.

heard people complain about short barrels. but I can guarantee 110% none of them would ever want to be on the receiving end of even one round

IMHO there is no point to using sub-sonic ammo without a can.  Cans and subs are made for each other and are somewhat mission specific -- stealth (it's harder to determine the source of incoming from a distance) and entry work (a team needs to comunicate) and just having a blast without taking out your ears.

Imagine 30 rounds each from a few people in a close urban environment.  The 300 really shines when you need a quiet and maneuverable PDW type weapon.