First AR for defense. Needing advice.

[redstategunnut]

I respectfully disagree. I've seen the results of a polymer tip / ballistic tip bullet .223 commercial hunting load out of an AR-15 carbine on a nearly 200 lb white tail buck. The gentleman who harvested the deer placed the shot just behind the shoulder, squarely in the rib cage. The buck walked a very short distance, and collapsed as it expired. There was a massive blood trail originating at the entry wound. The gentleman's father described the internal damage as "turned the heart and lungs into strawberry soup" from the ballistic tip bullet's violent fragmentation. There was no exit wound.

Switching to a bonded core copper jacketed soft point or a solid copper JHP bullet of 55 grains or heavier in .223 Rem or 5.56 NATO cartridges results in excellent penetration on automotive safety glass. ATK (parent company of Speer and Federal Cartridge Company) and other manufacturers have published these results across various media.

I specifically restricted my comment about terminal ballistics to CQB range. I did not say a 5.56 can't make a mammal DRT (dead right there), it can. I'm well aware some 5.56 loads can also shoot through safety glass. All one ounce slugs shoot through windshields and outperform 5.56 as far as maintaining terminal ballistic capability.
I continue to maintain that at CQB range a load of 00B is a better man stopper than a 5.56.
The shotgun has a niche, and within that niche it is king. The 5.56 is far more versatile and also extremely effective across more self defense scenarios. Were I picking between having only a shotgun or an AR, I'd pick the AR. That said, there are scenarios in which the shotgun is a better choice. We can't know in advance what our "scenario" will be, so the AR is always a "correct" choice whereas the shotgun might not be.

 

[ugaarguy]

A 45ACP HP out of a conventional handgun penetrated the same wall, at the same range, better than a .223Rem HP out of an AR15. Is that correct?

I'll live that for hso to answer, but I'm not surprised at all. It's the same result that every test gets. Stick with me and I'll explain it.

The first part involves drag:

Handgun bullets are basically round balls with flat bases. When they impact a barrier, they don't really tumble, they just spin end over in. Their drag profiles are barely changed.

On the other hand, .224" diameter bullets of 50 grains or more are basically long cylinders with conical tops. When these projectiles impact a barrier they actually do tumble, and it drastically changed their drag profile.

The second part involves energy and momentum.

Even a relatively light 115 gr 9mm bullet weights more than twice what a standard 55 gr .223 bullet weighs. The light for caliber 180 gr .45 caliber bullet still weighs more than twice what a 77 gr .223 bullet weighs, and conventional construction (i.e. copper jacket over lead core) 77 gr bullets are currently the longest projectiles that will load in a .223 Rem or 5.56 NATO case and still stay at or under maximum cartridge overall length for a STANAG magazine.

While traveling in the air we measure the power of a bullet in terms of kinetic energy. The formula for KE is Energy equals one half mass times the square of velocity, or E=1/2mv^2. What most shooters forget is that once the bullet encounters a barrier KE goes out the window. Now, we're dealing with momentum (expressed as p in standard notation). Momentum is energy at work, it has a far simpler formula. Momentum equals mass times velocity, or p=mv.

Lets look at those equations again. When calculating KE we only use half the mass of the projectile, but we more than make up for that because we multiply that half mass times the square of the velocity. However, when calculating momentum we get to use the full mass of the projectile, but we only get to multiply the mass by the velocity. It's quite easy to see how a light bullet at high velocity has quite a bit of energy, but the low mass converts to rather low momentum. The inverse is also true: a heavy bullet at low velocity has fairly low energy, but the high mass converts to very high momentum.

If we combine the drag characteristics of handgun bullets with their momentum and it's easy to see why they penetrate so much. Again the inverse is true: combine the drag charecteristics of light rifle bullets with momentum (lack thereof really) and its easy to see how why their penetration is so little.

If anyone else is interested I'll attempt to dive into soft barriers vs. hard barriers.

 

[ugaarguy]

I specifically restricted my comment about terminal ballistics to CQB range. I did not say a 5.56 can't make a mammal DRT (dead right there), it can. I'm well aware some 5.56 loads can also shoot through safety glass. All one ounce slugs shoot through windshields and outperform 5.56 as far as maintaining terminal ballistic capability.
I continue to maintain that at CQB range a load of 00B is a better man stopper than a 5.56.
The shotgun has a niche, and within that niche it is king.

That I agree with. I confess that I sometimes overlook that at very close ranges where a shotgun still has full velocity to go with the mass of its heavy slugs or buckshot pellets. That adds up to serious penetration and often bone breaking momentum.

 

[Al Thompson]

YZ,

Hands down, best interior wall penetration test I've found on the net:

http://how-i-did-it.org/drywall/index.html

 

[hso]

YZ,

The .45ACP out of a standard 1911 consistently penetrated two complete wall sets (drywall separated by 2x4 space with another drywall panel) more than the .223. The .223 generally yawed and keyholed or fragmented by the time it hit the second "wall", but the .45 kept a good orientation and penetrated 3 "walls" further.

All shots were made from ~20ft. and perpendicular to the "wall". The wall units were only a foot apart, but then we didn't have space to set them up 10 ft apart. Hollow points in the pistol calibers plugged with the drywall and behaved like FMJ (that surprised us as well).

Look up the Myth Busters episode of them shooting into water demonstrating that heavy rounds penetrated further while higher velocity light rounds stopped sooner (and very high speed projectiles came apart).

It actually is very interesting to conduct these experiments yourself because you see immediately how the firearms and ammunition you actually might use will behave when hitting "interior walls".

I switched to an AR after that day for home use and the shotgun became a backup.

The pictures in Al's link resemble what we saw.

 

[mljdeckard]

I think you are way overthinking it.

I don't seen any real legal challenge in an AR v shotgun.

Most guns will work for most people most of the time.

The cost difference in bottom end ARs v top end ARs does not really reflect the quality difference. I think the law of diminishing returns comes in after a Colt 6920. The colors, accessories, and aesthetic perks improve, but not in proportion to the cost. And I think the vast majority of shooters will never drive a gun hard enough to expose any differences between a DPMS/Stag/Bushmaster and a 6920.

I think that if you take a 6920, set it up how you want it, and use good magazines, you will never have a reason to NEED to upgrade. (Even if you may still WANT to eventually.)

 

[YZ]

I've looked at the numbers. While at it, saw other informal tests. Overall results were mixed. The information was interesting and new to me, but it is not a game changer. As far as penetration and collateral damage, there are choices of buckshot and even heavy birdshot that vary greatly. As far as the internet publications, generally, I will take note, but will not make any serious decisions based upon them.

I own shotguns, but none of them tactical. I am most comfortable with handguns. In the past I kept a defensive shotgun. If I weren't a sports shooter today, I'd still keep it. The whole argument about which weapon is surely the best for a person you never met is boring if not idiotic. If you want an AR, or perhaps a water cannon, that's your choice. You don't need to convince me or the world.

 

[hso]

Someone experienced with clay or hunting shotgunning would be ill-advised to switch to an intermediate cartridge carbine just because someone said they should. They've invested time and practice hitting with a shotgun and they'd have to invest at least as much making the same hits with a carbine. If they're effective with a shotgun and don't want to spend the time and money to gain equal or greater skill with say an AR then they're better off sticking with what they're good with. Not missing is the objective, but they do need to keep in mind that they're shooting a much more highly penetrating weapon/load with respect to standard frame walls should they miss.

 

[ugaarguy]

The whole argument about which weapon is surely the best for a person you never met is boring if not idiotic. If you want an AR, or perhaps a water cannon, that's your choice. You don't need to convince me or the world.

For arguing over the net to be so idiotic, you've certainly been a willing participant. I'm also amused by how you now act as if your position has always been that an AR is an acceptable choice amongst others for home defense. Allow me you remind you of your original stance with what you've previously written in this thread:

I would refrain from recommending any AR for home defense, without knowing what type of residence you plan to lawfully defend. Most justifiable shootings are CQB where your namesake shotgun or a pistol caliber weapon would fit in better.

You hyperventilate over nothing. I don't like the ninja attitude of getting armed with a tactical rifle to "defend" one's apartment.

Oh forgot. What is a tactical rifle you ask Girodin. It is a select fire or semiautomatic center fire rifle originally designed to kill humans. As opposed to a hunting rifle (kills innocent animals), or a target rifle (kills time and money).

I am glad that you've looked at the evidence presented, and accepted that an AR is a viable home defense tool, even if begrudgingly so.

Also, please, please understand that I and many other active THR members do not seek argument, but we will debate if necessary. Nor do we debate for the sake of debate. We debate because THR has become such a prevalent resource for firearms knowledge. Most of the active long time members here strive for accuracy in our posts. We strive to ensure that THR remains relevant for future firearms owners. I thank you for staying in this debate and keeping an open mind. I sincerely hope that you'll be this active throughout the rest of THR. Just try to avoid the name calling in the future. At times I also have a temper. If I act like a jerk or slide into name calling please call me out openly or via private message.

 

[YZ]

You've been shadow boxing here. I never said AR no good. I own one. I don't consider it the ultimate home defense weapon for most people in small residences. Not before, not now. It is fine for someone well practiced and for whatever reason committed to it. I believe #1 buckshot is reasonable. So I will say to anyone over the Internet. Don't worry there was a little fun for me too. I was suspected of working for the current administration (erased by mods) That was before I explained tactical rifle in jest. Orher than that no offense Ignorance etc don't bother me.

 

[taliv]

well now that that's settled...