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Great info, Andy. Thank you. My AR is probably my second choice for home defense after the Glock with nite sights and Streamlight TLR-1 on my bedside table. But I had never thought of this short-range POA situation before.

That's something I'm going to have to practice next time I'm at the range (despite the weird looks I'm sure I"ll get from other rifle shooters when I'm blasting away at paper 5 yards in front of me with an AR .

So top edge of a clay pigeon, I'm guessing approximately 2 to 3 inch difference between POA and POI at short range? Probably would be very close to being literally the difference between top of front iron sight and center of barrel opening?

Good point. Especially if you are shooting from behind cover, say a wall or a car, your sight-line could be clear and alligned, but your bullet travel line could dip down into cover. The same thing could happen if the bg is behind coved, maybe a cement wall, you take the shot w/o offset and think the bg is hit, when the shot went into the cover.

I find amazing that someone thinks an AR15 should be their go-to gun in the event of a home invasion. That's pistol or shotgun territory to me.

John Farnam is a fan of defense rifles and he covers this in rifle class. With the offset between barrel and optics, especially for the AR platform with fixed optics, it's important to know the two distances where point of aim and point of impact are the same. Between those ranges, POI is higher than POA. Outside those ranges POI is lower. Most people think about bullet drop at long distances but don't pay as much attention to the closer ranges. Thanks for the reminder Andy.

flb_78 wrote:I find amazing that someone thinks an AR15 should be their go-to gun in the event of a home invasion. That's pistol or shotgun territory to me.

I think all three will work well. With AR or shotgun, you have the "fear" factor which could help to disarm a conflict before it starts. With shotgun, you don't have quite the "control" over where the projectiles will go that you have with a rifle. In the admittedly not-all-that-likely scenario that Andy presents (BG holding your wife as cover), that would be a NO SHOT with a shotgun and likely with a handgun unless you're VERY SURE of yourself. But with a rifle/carbine of any kind, if you know what you're doing you have at least the opportunity to consider a shot like that (still not sure I'd take the shot myself).

With a rifle you obviously have very real fears of over penetration (of the BG or a wall) - hollow points, soft points, or best yet tactical plastic tips seem a must in HD situation.

My AR is currently my second choice (after Glock) simpy because compared to my shotgun (a Browning BPS with 28-inch field barrel), the AR fits the parameters better ... it's shorter (16-inch barrel), has a tac-light positioned just perfectly to activate with the thumb of my non-trigger hand, has a tactical one-point sling. I plan to buy at some point a HD shotgun with 18 - 20 inch barrel and a tac-light, but as of now my shotgun is really more of a field gun.

flb_78 wrote:I find amazing that someone thinks an AR15 should be their go-to gun in the event of a home invasion. That's pistol or shotgun territory to me.

My M4gery is usually my first choice when concealment isn't a concern.

I was shooting in a three gun match a few years ago, and using my Garand, so this didn't happen to me.

One of the other shooters reached a particular barricade and fired his AR at the required target and moved on. He was amazed to find that he had scored total misses on a couple of the targets while zero down on every other.

The problem was that as he transited from target to target his muzzle was occluded by the barricade while his sights were clear and every one of the shots he fired from behind the barricade went far awry. A couple of the rounds actually hit the paper, yawing to full sideways.

Muzzle awareness, muzzle awareness, muzzle awareness.

I couldn't even sight in on the target with my Garand without putting the muzzle past the barricade, so I had no problem, but the guys with the shorty barrels needed to be real careful.

AndyC wrote:Depends on the sight-height above the bore-line of the barrel, yup - I think a regular AR15 front sight is about 2.6" above the bore-line, IIRC.

Now, I doubt any one of us would ever actually need this info (well, I sure hope not) - but it's an interesting sort of really-get-to-know-your-rifle kind of thing

Andy,

I want to make sure I'm understanding this correctly because I'm a little confused...

As it happens, my Eotech sight co-witnesses with the irons on my flat-op AR. So I guess that means that the reticle on the Eotech is approximately 2.5" above the bore. Now, the rifle has been zeroed for 25 yards, which with 55 grain M193 ball, also means a 250 yard zero if I understand it correctly.... 25 yard zero as the bullet is climbing the arc of its trajectory, and 250 yard zero as the bullet is descending the arc of trajectory.

Now, although there is a curve to the trajectory between the muzzle and 25 yards out, for all practical purposes it is a straight line from that close. If I get 2.5 inches of bullet rise over 25 yards (the vertical distance from the bore line to optical zero), then I would be getting .25 inches of rise for every 2.5 yards traveled, or approximately .1" of rise for every 1 yard traveled. So a target that is 2 yards away (6 ft.) will have a POI of 2.3" lower than POA because the bullet will have climbed .2" in 2 yards (2.5" from bore to optical zero, minus .2" of rise for 6 horizontal feet covered). Therefore, at 6 feet away, I need to hold over by about 2.3" in order to make the desired POI.

Am I figuring this correctly?

AndyC wrote:There were some rather sober faces later, imagining the consequences of, for example, someone taking the wife hostage and having to take a precise shot at 5 yards at part of the bad guy's head visible directly above hers - ouch. Anyway, just thought I'd share for those of you who might not have done close-range work before with a rifle - something you can try out for yourselves.

I honestly don't think I would have the nerve to take that shot if there was even the remotest possibility of hitting my wife. I would wait for another opportunity to shoot.

Now, although there is a curve to the trajectory between the muzzle and 25 yards out, for all practical purposes it is a straight line from that close. If I get 2.5 inches of bullet rise over 25 yards (the vertical distance from the bore line to optical zero), then I would be getting .25 inches of rise for every 2.5 yards traveled, or approximately .1" of rise for every 1 yard traveled. So a target that is 2 yards away (6 ft.) will have a POI of 2.3" lower than POA because the bullet will have climbed .2" in 2 yards (2.5" from bore to optical zero, minus .2" of rise for 6 horizontal feet covered). Therefore, at 6 feet away, I need to hold over by about 2.3" in order to make the desired POI. Am I figuring this correctly?

Yes, your methodology for that is excellent!

BTW, the correct name for that phenomenum is "mechanical offset". Snipers deal with that not infrequently - in fact, the shortest law enforcement sniper shot on record is 11 feet 1 inch, inside a structure.

With my primary .308, which is zeroed at 100 yards, the bullet rises to the line of sight of the optic at about 30 yards from the muzzle, and is within 0.1 inches of that line until 106 yards.

It's a useful thing to know.

And as well is it good to know that your muzzle may not be clear even though your line of sight is. Where I work, we have lots of bullet holes in barricades, vehicles, and other supports to attest handily to that. We have to watch the students carefully to ensure that they don't get injured by blowback.

Holy crap. I just thought I knew "something" about guns...

Using a rifle is definitely something I hadn't imagined in my home in a a problem arises situation, however, my wife is now equipped with a SG, and I assume that if I or her were "taken hostage" where either of us were being used as "shields" for the BG, then it would be a no-go situation with the SG.... I know I wouldn't take the shot and I'm certain she wouldn't either... but with an AR style rifle (non scoped rifle or red-dot w/co-witness iron sights) I don't think my wife would have the confidence to use that knowing the POA and POI that you guys just discussed.

So going through the scenarios, what do you think we should do with our ARs in terms of sighting in.... 25 yards is pretty much the standard, just work at practicing closer quarters shooting and muscle-memory (brain and otherwise) that we need to aim 1" higher closer than 25 yards?

This is great information... You don't find this info everyday.

sneedb82 wrote:So going through the scenarios, what do you think we should do with our ARs in terms of sighting in.... 25 yards is pretty much the standard, just work at practicing closer quarters shooting and muscle-memory (brain and otherwise) that we need to aim 1" higher closer than 25 yards?

This is great information... You don't find this info everyday.

I think that in most situations, 1" higher or lower (or left or right) isn't going to make a bit of difference if you are shooting to center of mass with an AR15. Rifle rounds are simply devastating - even smaller lower power rounds like the 5.56/.223 - when compared to pistol rounds. I would MUCH rather be shot by a pistol than a rifle... ...if I am to be shot at all. Your bigger problem when shooting an AR, most particularly inside the home, is over-penetration if you are shooting FMJ ammo. If you are going to use an AR for inside the home defense, then some kind of soft tip/hollowpoint/frangible ammo would be the preferable load.

Think COM in HD situations. Now, can I hit a human head sized target with my AR at any distance inside of my home? Absolutely, and easily - with precision, slow, aimed fire to an immobile target. But in a HD shooting situation, you're not likely to have that luxury, and even with an accurate weapon like an AR15, you're going to be hard pressed to hit a moving target the size of a human head. It is a lot harder than you think it is. And when you factor in other things like poor light, your own physiological reactions to the adrenaline dump, the presence of other family members (and their mental/physical conditions at the moment), and anything else which is likely to contribute to the chaos of the moment, shooting to the largest, and therefore easiest to hit, target is the only thing that makes any kind of sense. That would be the center of mass.

At least that's my 2¢.