Which caliber for HD AR pistol?

[Perd Hapley]

I'm looking for articles on the best caliber for a home defense AR pistol. Apparently 5.56 is now considered less of a risk for over-penetration than shotguns or pistol rounds? But do .300 BLK or .350 Legend accomplish the same thing with less noise/flash?

[Ben]

I'm not a big expert, but I'm using .300BO for the house carbine, both for its (from what I have researched) better performance than 5.56 out of a short barrel, and because of how well the .300BO subsonic works with a can in front.

I recently bought a 7.62x39 upper just for a range gun, but have also been reading that some consider it a cheaper alternative to .300BO with nearly the same benefits. I haven't researched enough to know how accurate that is, and I don't think I've ever seen subsonic 7.62x39 on the shelves.

[Bogie]

Why not just get a glock with a gigglestick or two? The only real advantage for an AR pistol in home defense is the magazine capacity, and the whole package is kinda big and unwieldy.

[Boomhauer]

Why not just get a glock with a gigglestick or two? The only real advantage for an AR pistol in home defense is the magazine capacity, and the whole package is kinda big and unwieldy.

I’m guessing he means an AR pistol with a brace.

[Bogie]

Which means an even larger package... May as well just do a carbine. The AR's design with the fire control group, etc., all behind the magazine makes for length before you even add a barrel...
 
Frankly, I have to tell you that I like the Hipoint carbine in .45... But my house gun, if I need a rifle, is my .357 Trapper lever gun - and there is an AR carbine in the safe... Furthest shot from anywhere on this property would be 75 yards or so.

[dogmush]

Why not just get a glock with a gigglestick or two? The only real advantage for an AR pistol in home defense is the magazine capacity, and the whole package is kinda big and unwieldy.

Having worked with guns inside building pretty extensively, I have to disagree.  An SBR (because face it, that's what we're talking about here) is one of the best close in weapons around.  It is easy to aim and control (especially on follow up shots), an order of magnitude better against people then a pistol, and as compact (when in a firing position/low ready) than a pistol (when also in a firing position/low ready).  There's a reason no one slings their rifle and draws a pistol when entering a house.

Perd,
TLDR:  5.56 in the right setup is as good a caliber for indoors as any, and better than most, plus is cheap and has a lot of knowledge about what works and what doesn't.  Stick with that.

Longer version:
5.56 needs to be going in excess of 2500FPS (ish) to both be effective on people and fragment in a wall to decrease over penetration.  For the M193 and M855/M855a1 loads and clones this is easily obtainable from a 10.5" barrel out to 50(ish)m.  (There are a lot of variables)  Inside a building is no problem, unless you live in a warehouse.  so anywhere from 10.5-14.5" is a good sweet spot for 5.56 and the 10.5" end is pretty good for inside.  Under 10" not only does velocity suffer, but the noise and flash start to get really bad.  I had a 7.5" 5.56 for a little bit, and while it wasn't that much louder than a rifle, the flash was obnoxious, even with a flash hider.  Speaking of which, a can would be the best for this purpose, but lots of folks don't have one, or don't want to run one on a home defense gun.  If no can, then you will want a very effective flash hider.  Stay away from anything resembling a break or compensator.  In a building the concussion of a brake is way worse than the flash of burning powder.

.300 blk subs puts you right back into the over penetration issues of pistol and shotgun projectiles, and IME .300blk supers aren't less concussive or flashy then 5.56.  Or at least not enough to be worth the added cost.

I currently run a 10.5" 5.56 with a can as my go to carbine, and have done shoot houses with it.  It's very handy, fast on target and easy to make good hits.  Anything that is built to the basic Mk18 specs will make a great indoors carbine. 

I realized I talked more about rifle setup than caliber, which was the question you asked, but with an AR pistol it's important to make sure the gun works well with the caliber you've chosen.


(edited to fix typo)

[Ben]

Oh, when I said carbine in my above post, I meant AR pistol. Specifically for what I said I was using, the Sig Canebrake. I always seem to use AR carbine and AR pistol interchangeably. 

Also, I don't really have a big "overpenetrating and hitting a neighbor's house" issue here, so others MMV.

[WLJ]

I went the bullpup route. The same or near to the same total length as many AR pistols but with a full length barrel

[Perd Hapley]

The gun I had in mind would have about a 10" barrel (maybe less if 300 BLK). I will probably not fork over silencer or SBR money, though maybe I should. I'm not married to having a brace. Will be at least a year before I start on this one. We'll see what's legal then.

[dogmush]

As a fan of, and owner of like 5, AR pistols:

If you aren't going to put a brace on, don't get an AR pistol.  With a bare buffer tube it's unsuitable for anything other than wasting money at a range, and certainly not a home defense weapon.

SBR stamp is, of course, another subject.

[Perd Hapley]

As a fan of, and owner of like 5, AR pistols:

If you aren't going to put a brace on, don't get an AR pistol.  With a bare buffer tube it's unsuitable for anything other than wasting money at a range, and certainly not a home defense weapon.

SBR stamp is, of course, another subject.

 Noted. I was thinking AR because it's easy to build what I want, and hang lights and junk on it, and get magazines and parts for.

[MechAg94]

One issue with subsonic 300 blackout is making sure your chosen HP ammo will reliably open up.  A lot of subsonic 300 blackout will not.  I think most didn't use the best bullets for that.   

[Bogie]

In a moment of brokeness, I sold my old Stevens coach gun (18.5" barrels, rabbit ears) to a buddy for what I had paid for it... Loaded with a pair of low-recoil #4 buck, that thing was compact and purely evil to look at. Remember - a break-action shotty has next to no "action" length, like you have with a pump or auto...

[MillCreek]

^^^In my travels hither and yon through the LGS, I always keep an eye out for a Stoeger Double Defense or a Mossberg Maverick HS 12.  I would like to pick one up but have never seen one in real life.

[HankB]

One issue with subsonic 300 blackout is making sure your chosen HP ammo will reliably open up.  A lot of subsonic 300 blackout will not.  I think most didn't use the best bullets for that.   

I thought the idea behind a .300 Whisper (very nearly a .300 Blackout) was that extremely heavy bullets at barely subsonic velocity would be barely stabilized, and become destabilized on impact, removing the need for expansion? IIRC, JD Jones wrote something to the effect that the bullet only had to be stable enough so that you wouldn't get a baffle strike if your gun was wearing a can, so it would tumble after - NOT before! - it hit.

[MechAg94]

I thought the idea behind a .300 Whisper (very nearly a .300 Blackout) was that extremely heavy bullets at barely subsonic velocity would be barely stabilized, and become destabilized on impact, removing the need for expansion? IIRC, JD Jones wrote something to the effect that the bullet only had to be stable enough so that you wouldn't get a baffle strike if your gun was wearing a can, so it would tumble after - NOT before! - it hit.

The gel test I have seen don't show that.  It will still make a hole, but I think you can do better.  I think if you go with 300 blackout, the supersonic ammo will probably be more effective.  If are using a suppressor, it will still be quieter.   At home defense ranges, suppressed firing won't be quiet enough that people won't hear you. 

If this is just for HD, IMO, stick with a 10.5" barrel and 5.56.  PSA sells their 10.5" upper pretty cheap.  5.56 can be found anywhere and is cheaper.  As mentioned above, you are still going to get 2800 fps or so.  Just use a muzzle device that directs the sound down range a bit (anything but a muzzle brake).  The local Academy stores have restocked on the common ammo types.  They have a ton of 5.56.

[MechAg94]

^^^In my travels hither and yon through the LGS, I always keep an eye out for a Stoeger Double Defense or a Mossberg Maverick HS 12.  I would like to pick one up but have never seen one in real life.

It has been a while since I have seen a shorter SxS shotgun for sale.  CZ makes them, but those are more expensive than a tricked out home defense pump shotgun. 

[HankB]

. . . The local Academy stores have restocked on the common ammo types.  They have a ton of 5.56.

What's it running? $600/1000 or so?

[MechAg94]

What's it running? $600/1000 or so?

Yeah, in that range, but it is 150 and 200 round packs with some 20 round boxes. 

They have 9mm, 45, 40, 308, and 223.  A little 380 also, but very little of any other calibers at all.

[Perd Hapley]

So, if SBRs and cans are ruled out by legal and cost concerns, it makes me wonder if the poor man's version is just an AR with a 14.5" barrel, and an appropriate muzzle device permanently attached. It would be a few inches longer than a silenced pistol.

[dogmush]

Yep.

A 14.5" barrel with, for example, a Surefire flash suppressor pinned and welded is like 16.2". Surefire ships their non suppressor mount muzzle devices with a blind pilot hole already drilled to facilitate that very thing.

[MechAg94]

If suppressors or braces are not an option, just get an inexpensive AR that works for you.  No need to get picky on barrel length at all.  Lots of options become available as the money spent goes up. 

[MechAg94]

Saying all that about AR's, if cost is an issue, there are plenty of really inexpensive pump action shotguns out there that would be decent for home defense.  A lot of them are available around $200.  These are usually foreign made copies.  Mossberg makes a Maverick 88.  There is a Stevens 320 model in various configurations. 

[Perd Hapley]

Saying all that about AR's, if cost is an issue, there are plenty of really inexpensive pump action shotguns out there that would be decent for home defense.  A lot of them are available around $200.  These are usually foreign made copies.  Mossberg makes a Maverick 88.  There is a Stevens 320 model in various configurations.

Like I said, the advantage of the AR is that, apparently the 5.56 (and maybe the Blackout?) are less of a danger for overpenetration. Plus, the modularity thing.

Not looking for the absolute lowest cost, really.

[Lennyjoe]

My main house gun is a 12 gauge pump with buckshot to cover the hallway with 1 blast…