Which would be better and why a 5.56 SBR/Pistol or 300 Blkout SBR/Pistol either would be suppressed. I'm in a small apartment building for what it's worth. Please post your reasoning and or experiences. Thanks in andvance.

James

I have both and use 300blk. Personal prefernce I suppose but I like heavier bullets. I also use subsonics when its on home duty which is a plus for indoor use at the cost of termianl ballistics, all else being equal.

WARPIG602

Is yours suppressed? Any pics of it I can see?

James

The 223/5.56 cartridge is more dependent upon bullet velocity, and therefore barrel length, for ballistic effectiveness than the 300 Blackout. Assuming supersonic loads are used*, the 300 achieves the same bullet energy from a short barrel as the 223/5.56 does from a carbine. I would therefore choose the 300 in a short barrel platform for that reason alone.

And FWIW, it seems to me that the 300 benefits more from a suppressor even with supersonic loads than the 5.56. A deputy I know has a 5.56 SBR with integral suppressor and it’s not all that quiet. Plus if he ever engages someone at close range with the thing, the muzzle blast will probably incinerate the BG even if the bullet misses. In my opinion SBRs or pistols chambered for 223/5.56 are noisy range toys with poor ballistics.

* And if I were going to depend upon an AR variant weapon chambered for 300 Blackout for self-defense, I wouldn’t rely on subsonic loads.

If you're going to pay $1/rd for subsonic, it might as well be 300BLK. If anything, I'd use Hornady Black short barrel ammo if running 223/556.

I've got an 8" 300BLK upper...need to stick it on my SBR lower w/ MVB stock. Should be Honey Badger-like in size and form.

Not sure if I have any of the MK18(300blk) suppressed but it uses the same can as my V7S shown here with the Dead Air Sandman K. Before that I was using my Omega with Dead Air adapter.

V7S:


MK18: Now wearing an Eotech XPS3. Excuse ths shitty photo, was undergoing its initial 24hr CLP bath

Even suppressed, shorter barrels are pretty loud. I have an 11.3" barrel 300blk upper. With the same suppressor, it is louder with supersonic ammo than my 14.5" and 16" barrel 223 uppers. The little I've been around 10-13" barrel 223 uppers has shown me I don't want to be around them -- even suppressed.

Subsonic 300blk ammo with a suppressor is pretty quiet. If my safety depended on it, I wouldn't use subsonic ammo in a carbine -- one has essentially turned a long gun into a handgun, when considering kinetic energy.

If one must have a short barrel carbine for defensive purposes, then 300blk over 223 any day. I'm uncertain how 300blk rounds do in the fragmentation department. Many good 223 bullets fragment quite well in sheetrock, limiting their energy in 2nd or 3rd rooms, in the event a stray bullet hits a wall. I don't know if such studies have been done with 300blk bullets.

My can of whoopass is a 8" 300 blackout SBR. I have a can but in a HD situation I probably wouldn't use it. They really change the guns handling characteristics and not for the better. Also they make the gun a lot quieter. I want everyone to know the situation in my house is so bad I have to use the can of whoopass. I want no question of the level of force being deployed at that time.

quote:

Originally posted by guardianangel762:
My can of whoopass is a 8" 300 blackout SBR. I have a can but in a HD situation I probably wouldn't use it. They really change the guns handling characteristics and not for the better. Also they make the gun a lot quieter. I want everyone to know the situation in my house is so bad I have to use the can of whoopass. I want no question of the level of force being deployed at that time.

What kind of can are you using?

If you can't have MV, then you want bullet-weight.

With an SBR or rif-ol, you are basically guaranteed to have sub-par muzzle velocity. I would go .300 BLK supers given the three options (5.56, 300 sub, 300 super), if noise was not an over-riding factor.

I'm leaning towards the MCX pistol w brace in 300 blkout with the 9" barrel. Or should I go for a longer barrel?

James

I have a 10.5" 5.56 and an 8" 300blk. For home use, I like the suppressed 300blk better. It's shorter overall but I do load it with supersonic. I tried putting down deer with subsonic and was not happy.

The 5.56 was just to mimic our entry guns at work which were Colt M4 Commando 11.5" rifles. But even we've switched back to 16" Wyndham (??!!!) rifles to standardize everyone since we don't use suppressors on rifles at work (???) and only on subguns (???). New commander is goofy. Must know someone who sold us the crappy Wyndhams. We're allowed to use our own now so I bought a Daniel Defense.

quote:

Originally posted by depusm12:
I'm leaning towards the MCX pistol w brace in 300 blkout with the 9" barrel. Or should I go for a longer barrel?

James

9in should be fine for 300blk.

quote:

Originally posted by WARPIG602:


What kind of can are you using?

Silencerco Omega

quote:

Originally posted by fritz:
If my safety depended on it, I wouldn't use subsonic ammo in a carbine -- one has essentially turned a long gun into a handgun, when considering kinetic energy.

Yes, and it doesn’t require scientific testing to demonstrate that fact. Most 300 Blackout subsonic loads use bullets in the 200-220 grain range and at, well …, subsonic velocities. The three loads I’ve chronographed from a 17 inch barrel were all very close to 1030 fps, and we would of course expect them to be significantly lower from shorter barrels. Velocity data for subsonic loads and short barrels is scarce, but one limited test indicated that a 220 grain bullet with a claimed velocity of about 1050 fps from 16" averaged well under 1000 fps from 10.5". From 8 or 9 inches, I’d not be surprised that it was in the 800 fps range.

By way of comparison with a handgun cartridge with bullets in the same weight range, look at the 45 ACP. From a P220, the 200 grain +P Gold Dot averages about 1060 fps. The 230 grain standard pressure Gold Dot runs about 800 fps.

And bullet velocities in the subsonic range aren’t the only thing to consider in a self-defensive cartridge. First, most subsonic factory loads for the 300 Blackout use open tip match-type bullets that aren’t intended to expand even at real rifle velocities (2500+ fps). One exception is the Hornady round that’s loaded with a 208 grain A-MAX bullet. A-MAX bullets are usually expected to expand, so I’ve focused my examination on that Hornady 300 Blackout subsonic load.

In shooting the Hornady 208 grain A-MAX at water filled milk jugs and water-soaked newspaper*, none of the dozen or so bullets I recovered show any sign of expansion. Whether they start to tumble quickly enough in the tissue simulant to produce additional wounding effects I can’t really say; it seems that some may do so, while others don’t. The limited tests I’ve found on the Internet aren’t of much help in answering that question either. There is one gelatin test of a subsonic 220 grain nonexpanding bullet that shows the projectile penetrating about 16 inches before it starts to tumble. That performance is hardly ideal for either wounding effect or limiting over-penetration.

In short, Gold Dot handgun bullets in the 200-230 grain weight range expand reliably and pretty spectacularly when fired at subsonic velocities. As far as I’ve been able to determine, 0.30 caliber rifle bullets in that weight range don’t expand at all, and may or may not even tumble. If subsonic 300 Blackout bullets don’t expand reliably and are much smaller in diameter than any common defensive handgun cartridge bullets, which would we rather use in a critical situation?

* Neither is any sort of scientifically valid ballistics test medium. I have found, however, two things: A hollow point handgun bullet that’s going to expand at all under any circumstances can be expected to expand in water. Rifle bullets, including FMJ military style, fired at rifle velocities will usually expand or/and tumble and fragment in soaked newsprint.

Thank you, WARPIG602, I will have to try some of that.

quote:

Originally posted by sigfreund:
Thank you, WARPIG602, I will have to try some of that.

How many rounds do you typically use for your testing?

quote:

Originally posted by guardianangel762:
My can of whoopass is a 8" 300 blackout SBR. I have a can but in a HD situation I probably wouldn't use it. They really change the guns handling characteristics and not for the better. Also they make the gun a lot quieter. I want everyone to know the situation in my house is so bad I have to use the can of whoopass. I want no question of the level of force being deployed at that time.

Have you ever fired an SBR indoors?


I would rely on my bullets to stop a threat. Not on the immense levels of noise which I would also be victim to.



Just my 2 cents but my can stays on my AR pistol all the time. I chose 5.56 but I think supersonic 300blk is still an excellent option. I just preferred 5.56 with good quality ammunition.

I have an 11.5" BCM SBR that I run a Sandman L on.
Shooting 5.56 and 300 BLK supers are hearing safe out of my setup suppressed. A guy at the range came over while I was zeroing my Aimpoint T2 and asked what I was shooting. He thought I was shooting a pellet rifle. I wouldn't say it's pellet gun quiet, but it is hearing safe.