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TAM's thread about 5.56 NATO ballistics got me to remembering how we zeroed our M16s back in the '60s. I recalled sighting about 1" low at 25 Meters and that gave us a battle sight zero out to 350 Meters or so. Well after some searching on the net and crunching some data with Remington Shoot software I have a sight setting to offer.

With M855 (62gr green tip) adjust your sights to shoot .75 inches low at 25 yards, this will give you a zero of 325 yards and a point blank range of 382 yards. At no point in it's flight will the bullet be more 5 inches above line of sight nor more than 5 inches below line of sight.

With M193 (55 gr FMJ) you would set your sights to shoot .84 inches low at 25 yards and have a 340 yard zero and a 401 yard point blank range! Think of it 0-401 yards with a COM hold and 500 with a head hold.

I can assure this method works. I have practical experience using it.

If I had the eyes for it, I'd be interested, but I just can't see that far without a scope. The other method—zeroing at 50 yards—gives you from -2" to +2" out to 250 yards, which far zero at about 225.

Maybe I'll get laser lasix and re-zero my rifle.

My '03-A3 and my Garand are zeroed that way (battle sighted), my AR is about .5" low at 25 yards on the dot sight, but my co-witness irons shoot a little lower on purpose.

Don't forget, though, that this is all dependent on how high your line of sight is from the bore.

SRH78 wrote:Don't forget, though, that this is all dependent on how high your line of sight is from the bore.

That was all factored in when I made the calculations.

The program asks for sight height, BC of the bullet and muzzle velocity couple that with the size of the vital zone of your target and it will tell you what your point blank range is and where to set your sights at 25 yards. You can also change the sight in distance if you don't have a range you can use 25 yards.

Obviously, there are different schools of thought about zeroing. The reason I originally posted my other thread was because of the 9" above bore at apogee with a 25 yard zero. You get a second zero pretty far down range (350 yards), but you pay a penalty in trajectory by doing so, and the bullet drop beyond the secondary zero (more than 24" low at 470 yards) makes it impractical for long range use. (see illustration)



Here are the equivalent charts for 50 and 100 yard zeros:





Mojo's solution—"a zero of 325 yards and a point blank range of 382 yards. At no point in it's flight will the bullet be more 5 inches above line of sight nor more than 5 inches below line of sight"—is better than the 25 yard zero too. To my mind though, one has to consider the practicality of 5.56 NATO as a long-range cartridge. In perfect conditions, and with the right (target grade) rifle, one can do amazing things with this cartridge. Easily the most accurate rifle in our safes is my son's RRA 24" bull barreled varminter. It will shoot 5 round groups into 1/4" on paper at 100 yards with such consistency it actually becomes a little boring.

But out in real world, living targets are hardier than a thin sheet of paper, and at longer ranges the power of the 5.56/.223 cartridge tapers off dramatically along with its ability to buck the wind. One the one hand, there is the ethical responsibility to make a clean kill—even on a varmint—and on the other hand we have seen the reintroduction of .308 calibered squad-level sharpshooter rifles in Iraq and Afghanistan because it is a proven fact that in a long range and windy environment, the much heavier and more stable .308 bullets will be more effective against human and larger animal targets.

So for me, I've decided that out beyond about 250-300 yards, I'm happy to use my R700 or AR10. Inside of 300 yards, I have a lot of confidence in my carbine. These statements are true for me whether we're talking white tails, hogs, and coyotes, or we're talking mutant zombie bikers, foreign invaders, or a government turned on its people.

TAM, I am not advocating shooting at anything or anyone at long distances nor do I think the method you are using is incorrect.

I was simply offering another way to zero an AR/M4/M16. There is no reason to engage a target beyond 50-60 yards in normal self defense/home protection situations. The method I use will place the flight of the projectile no more than 5" above line of sight to 5" below line of sight and gives the maximum point blank range.

By using this method I can be assured of being able to get a hit at a long distance if the need ever arises. Remember, if you are in a combat situation, meaning like in A'stan or Iraq you take the shots you have to with the weapon you have at hand.

Good information fellas. I sighted my AR in to be 0" at 50 yards. Bases on the information in this thread and the other thread TAM started I'm just going to have to go back out to the range and double check it. Bummer....

I use my AR for home defense and don't expect to shoot anything at more than home distances, at most 15 yards in my house. That is where I have mine zeroed.

MoJo wrote:TAM, I am not advocating shooting at anything or anyone at long distances nor do I think the method you are using is incorrect.

I was simply offering another way to zero an AR/M4/M16. There is no reason to engage a target beyond 50-60 yards in normal self defense/home protection situations. The method I use will place the flight of the projectile no more than 5" above line of sight to 5" below line of sight and gives the maximum point blank range.

By using this method I can be assured of being able to get a hit at a long distance if the need ever arises. Remember, if you are in a combat situation, meaning like in A'stan or Iraq you take the shots you have to with the weapon you have at hand.

Mojo, not a problem. I didn't take it as an indictment. I was just talking about what I think will work for me best. I find myself having less ability to calculate on the fly, so to speak, than I had in years gone by; so for my pitiful remnant of a brain, ±2" is a lot easier to comprenday than ±5". As far as distance goes, I apologize. I thought that the increased range that ±5" gives you was what you were after. My mistake. And I agree with you that "[t]here is no reason to engage a target beyond 50-60 yards in normal self defense/home protection situations." In fact, at least where I live, it is difficult to conceive of a SD situation at more than pistol range. It's pretty peaceful in my neck of suburbia. Other than hunting and recreational range time, all of my long guns were chosen for their practicality in the three more rough uses I listed: "mutant zombie bikers, foreign invaders, or a government turned on its people." The Founders dealt with all three, and the tangos all wore red coats.

OK, now that I've scratched my dime-store-novel itch, I'll revert to being a fat older guy with failing eyesight. Seriously though, the more I shoot my AR, the more I like it, and the more I respect the platform and Eugene Stoner's vision. So far, I've only ever shot mine at the range with one exception, but I would really like to give it a try on a hunt. It's pretty accurate, and it doesn't weigh nearly as much as any of my other rifles. Here's a picture of a hog shot with a carbine that my son built for his boss (warning: no blood, but there is a dead animal in the picture): http://whamproductions.com/images/misce ... forweb.jpg. That's a pretty good sized hog. I don't think the range was too far....almost certainly inside of 100 yards. His boss shot it with two 55 grain FMJs right behind the right ear. You can't even see the entrance wounds. But apparently the damage on the offside was considerable.

BTW, has anybody ever seen a comparison for barrel length, comparing the ballistics at extended range (for the cartridge) between a rifle length standard M16 barrel, and a standard M4 barrel? I'm curious about how much velocity the short barrel loses, and the effects of that velocity loss on trajectory.

MoJo wrote:

SRH78 wrote:Don't forget, though, that this is all dependent on how high your line of sight is from the bore.

That was all factored in when I made the calculations.

The program asks for sight height, BC of the bullet and muzzle velocity couple that with the size of the vital zone of your target and it will tell you what your point blank range is and where to set your sights at 25 yards. You can also change the sight in distance if you don't have a range you can use 25 yards.

For your rifle, yes but that was a reminder for others that their line of sight may be higher or lower relative to their bore. Also, barrel length comes into play as it effects velocity. It difficult to make general statements about sighting in due to differences in rifles.

The Annoyed Man wrote: . . . BTW, has anybody ever seen a comparison for barrel length, comparing the ballistics at extended range (for the cartridge) between a rifle length standard M16 barrel, and a standard M4 barrel? I'm curious about how much velocity the short barrel loses, and the effects of that velocity loss on trajectory.

I have, but it's been a long time, and I was an active long range target shooter at the time, and the analysis (which excluded the M4 because it didn't even exist then) was based on whether it was even feasible to use M16s at the National Matches. Now that we have seen it happen, the people who were nay sayers 40 plus years ago probably would have to eat their words, if they have any real teeth left.

I, personally, could not see shooting what I considered to be long ranges with a 5.56, so I fell in the group that held that it was a close combat gun, and the NMs should continue with the M14 platform and stay in the respectable and wind bucking .30 caliber range. Of course, back then what we thought was a pretty good group at 1000 yards would get you laughed off the range these days.

I like having my rifles battle sighted, knowing that if I hold COM at any reasonable range, I will be hitting within inches of point of aim, if my increasing shakiness doesn't interfere, that is.

Funny aside - the other day we were out with some friends, neophyte shooters who are going to get CHLs, and shooting our way through a bunch of different handguns for comparison purposes. I had just shot a respectable group with my 1911 .45 and the female member of the other couple asked me how I was able to shoot so well shaking the way I do. I told her that I just time my shots to the shakes, always firing in the same part of the cycle.