rethinking my iron sight zero for a 6 o'clock hold

[ErikW]

(OK, all you scoped guys can go away now, unless you're using some kind of post reticle, such as the Trijicon Accupoint.)

I've always liked the idea of using a rifle zero that lets me maximize the flat path of the trajectory so as to avoid sight adjustments or hold-over/under. Right now, that's a 185 yard far zero to keep the bullet within about an inch of the aiming point out to 210 yards or so. Great theory, but it falls apart in practice.

This bit me in the ass at the SMM3G. What happens with farther and smaller targets, especially the flasher plates, is I hold the front sight post at 6 o'clock under the target. The problem is my bullets fly to the top of the post, but the meat of the target is several inches above the post. Ideally, I would bisect the target with the sight, putting the top of the post directly in the middle. In the real world, it's hard enough just finding the target with two eyes; with one eye through a tiny, light-reducing aperture, I have to see the whole target to aim, which forces a low hold. On the close paper targets, ideally, I would hold high to compensate for the 2.6" of sight height. In the real world, the interest of speed requires me to hold center of mass and bisect the target.

In the back of my mind I always figured the solution is to zero for a low hold. However, I always dismissed the idea due to the angles and the unfortunate fact that targets do not increase in size with distance. For example, zeroing 5" high to hit the center of a 10" plate at 100y would be 10" high at 200y (likely to miss over the top of the plate) because for a given angle, the elevation changes as distance changes. Or so I thought. That would be true if we were shooting perfect, undiffused laser beams. But we are shooting imperfect projectiles that fight the atmosphere as they constantly lose energy and are pulled down by gravity. Just when the angle becomes a problem, the bullet begins to drop, and suddenly a low hold zero is a good idea once again.

My favorite external ballistics software seems to confirm that a low hold is a good idea. To keep the bullet within half the size of a 10" MGM flasher plate, I came up with a 33y near zero and a 285y far zero.

Distance  Impact
(yards)  (inches)
025 -0.6
050 +1.1
075 +2.6
100	+3.7
175	+5.0
225	+3.8
250	+2.6
275	+0.8
300	-1.4
350	-7.6
400	-16.3
500	-42.7

Inside 50 yards, I will naturally aim to bisect the target with the post, so the small distance between aiming point and impact is ideal. When things start to get interesting and I have to hold low, the bullet will be impacting near the center of the target. At around 230y I need to start thinking about dialing in some more elevation for the rear sight.

Well, what do you think? It looks like a good plan to me, assuming course designers don't put clay pigeons out at 175 yards.

Edited April 15, 2004 by Erik Warren

[Sam]

Nice! I have problems losing sight of the plate under some light conditions. I locate it first, on top of the post, and then carefully bisect it. It takes time and it's very easy to lose sight of the plate. I'm gonna try it. Thanks, Erik.

[ErikW]

Out around 200 yards, plates are darn near invisible to me. The impacts make a random camoflauge pattern that masks the shape, causing it to blend into the background, especially a dirt-and-rocks berm. I have to spot them with two eyes "outside the sights" then find the target through the aperture. Centering the front sight post under the plate all but makes it disappear. Not to mention it's difficult to judge bisecting a circle when I can't really see the lower portion and the top portion is all fuzzy and nearly indistinguishable from the background because I'm focusing on the post.

[kurtm]

Use a 300 yard zero, just like the Marines! These 185 yd zeros or 283 yard zeros are like kissing your sister....it may make you feel good, but you don't want to get caught doing it I use the 300yd zero for both AR carbines and .308s like M1As and Fals, and AR10s with iron! KURT

[rhino]

I use this zeroing method:

http://groups.msn.com/TheMarylandAR15Shoot...esightzero.msnw

It gives you a first zero at 50 yards and the second at about 200 meters (note the mix of units), depending on the load and barrel length. It gives really good results, with impact being within an inch and a half either way from the line of sight from zero out to about 250 meters, especially for a rifle setup for defensive use.

If you have to shoot at longer distances, especially if you know them, I suppose it would be better to fiddle with your rear sight for each distance, but the IBZ removes the need for that for most shooting.

[John Dunn]

Shooting irons beyond 100yds should be considered trick shooting, and left to the likes of Bob Munden.

Put a scope on it.... you know you want to.

[ErikW]

kurtm and rhino, the issue isn't the zero distance, it's the sight picture used to obtain the zero and the sight picture used to shoot plates. What sight picture do you use to hit a 200 yard plate with your 300 yard zero?

250 meters, especially for a rifle setup for defensive use

Yeah, well I'm sure there's a really big need for 300+ yard defensive rifle shots, but this topic concerns shooting steel plates in timed competition events.

John, after I win Limited or Tactical-iron in a big 3 gun match by being the one and only entry, then I'll go glass. I read about these High Power guys shooting at 600 and 800 yards and I think it can't be that hard to hit plates out to 300.

It really sucks that I don't have a range where I can shoot past 100, let alone at various intervals to test my theory and confirm the calculated trajectory.

[rhino]

kurtm and rhino, the issue isn't the zero distance, it's the sight picture used to obtain the zero and the sight picture used to shoot plates. What sight picture do you use to hit a 200 yard plate with your 300 yard zero?

Yeah, sorry that I contributed to the drift ...

Confession: I've never shot at anything other than paper past 125-150 yards or so, and I've only shot at an 8 inch plate at that distance with a red dot.

For what it's worth, if I knew I had to hit plates at long distances with iron sights, I would definitely use a six o'clock hold for my zeroes. If your front sight obscures the target otherwise, it takes more time to see the plate on top of your sight, then guestimate where it probably is after you raise your sight picture enough to account for the COM hold.

I doubt if you needed my inexperienced opinion on this, but there it is.

It really sucks that I don't have a range where I can shoot past 100, let alone at various intervals to test my theory and confirm the calculated trajectory.

Can you think of a better reason to move to Montana or Wyoming?

[ErikW]

Actually, shooting a paper bullseye would be the same as a plate. However, with a bullseye, you are "cheating" by having the surrounding target paper and some sort of target frame as part of your overall sight picture. It does make a difference. If you're lucky you'll be able to see the MGM flasher supports as reference points and center your sight, using the supports as part of your sight picture. MGM lollipops offer no such help.

[rhino]

Actually, shooting a paper bullseye would be the same as a plate. However, with a bullseye, you are "cheating" by having the surrounding target paper and some sort of target frame as part of your overall sight picture. It does make a difference. If you're lucky you'll be able to see the MGM flasher supports as reference points and center your sight, using the supports as part of your sight picture. MGM lollipops offer no such help.

Heh ... on the rare occasions I've had to shoot at longer distances, it has been on the trusty IPSC paper target. That obviously give you some cheat room, at least with respect to elevation.

[Bear1142]

Erik,

I have to agree with Kurt, go with a 300 yard zero. If you use a 55gr. bullet around 3100 fps, you should be about 4" high at 100 and 5" high at 200. For any plates from about 75 to 250 yards, I just use a standard 6 o'clock hold and be done with it. I put the plate on top of the front sight like a lolli-pop and let her rip.

For some 100 yard practice, try using some 4" paper plates or some clay pigeons. It should give a pretty close approximation of a 200 yard 8" plate.

Erik

[Sam]

Erik, have you ever tried the KNS Precision front sight? I have one on my AR and it makes it much easier to see the far targets than the posts on my other rifles. My eye tends to look through it, rather than at it, as with a post.

[kurtm]

Erik:

I thought your ballistic program would have given you the answer of " where to hold " for 200yds with a 300 yd zero. Lolly pop, Lolly pop, Oh my little Lolly pop...well you get the idea! I hope some day I can also win limited /iron division. Maybe when the stars line up KURTM

[Helmut]

I personally love my lolli pops from MGM........as long as there is a 8" circle from 100-300yrds........DRILL IT! Just remember you have to see at what you are shooting at! 200yrd plate.....hold at the bottom of it, with a 300yrd zero.....

Kurt,,,,,,,congrads on the winning the Texas 3Gun Champ. in Limited Class! I know the 200yrd shots where tough.......good thing there was no heads on those damn things....haha.......

Take Care

Garret

[ErikW]

After I ran a fast 55 gr through the calculator using a 300y zero, now I see what you guys mean. It's what I proposed in the first post, but at a slightly different zero range to optimize the flat sweet spot. My slower 69 gr needs a 285y zero to avoid going too high.

[Helmut]

Erik,

You need to find a range with 300yrds......calculating and doing are to different animals....

I know alot of 3gun matches consider over 100 yrds long range..........There is a very challenging 3gun match at the NRA Whittington Center in August (Rocky Mountain 3gun).......you might want to come out and try it.........It will test even the best of them....I think I heard the furthest shot last year was 300 or so yrds...

Take Care

[ErikW]

I was pleasantly surprised to find my near zero (established on a long pistol bay) coincided with the calculated far zero the one time I got to use the 200 yard range. If I can match the calculated impacts of two points 130y apart, that's good enough for me.

[Jim Norman]

Open up your trusty and ever present copy of Hornady's two volume reloading and ballistics manual. Pick your bullet weight and your Muzzle velocity. Do the calculations.

For .223/5.56mm

With a 200 yard Zero and a 55 grain bullet traveling @ 3,000 fps. you will be about 3" high at 100 and 5" low at 300.

If you were only ever shooting at "Metric Targets" you could do as is currently done and zero at 42 yards. THis will keep you inthe effective "A" zone out to around 350 yards. A 62 grain makes very little difference, far less than your own variations for the type of shooting we do.

You can do the same with .308/7.62

Jim

[Chris]

Erik,

I remember Mike Vight talking abou zeroing his gun at about 250 yards. He said with that zero, he holds under on the longer targets and holds on the top of the closer targets.

It kinda sucks to have to cover a target to shoot it, but I guess you have to make the compromise somewhere and I would think closer is better. Also maybe think about using 62's or even 55's to get a flatter "sweet spot" trajectory.

The sight picture you were talking about in your original post is the common setup for 10M shooters (with notch and post sights). They use a six o'clock hold and sight their guns in high.

[InTheBlack]

Are your targets at totally random ranges or do you know the distance to within 25 yards or so?

It doesn't take long to click the elevation wheel, and if you have pre-calculated the number of clicks you need to maintain a six-o-clock hold you can write your dope on the buttstock.

[ErikW]

Dialing the e-wheel during a course of fire is undesirable. That's why it's important to exploit the sweet spot in your trajectory. I have a dope chart on my rifle to compensate for distances beyond my sweet spot and for wind drift.

[kellyn]

Consider an apeture front sight from JP. They rock on plates but they're a bit less desirable on paper. I'm currently experimenting with the JP front sight with interchangeable inserts. It's a trick sight but my favorite front sight remains the front post - which is super skinny in the JP.

I use a 250 yard zero, not the Kurt Miller/USMC 300 yard zero - which works very well but you have to hold a bit low on the intermediate targets. Plus I would not want to do what Kurt does - soon I'd be loading shotgun weakhanded. For 300+ yard shots, I let my breath out and as the post passes through the target, I let her rip.

I'm a big believer in the 6 o'clock hold on plates and other steel targets as it's tough to maintain a consistent elevation using a center of mass hold. Putting the pumpkin on the post is easier than putting the post in the middle of the pumpkin.

[Deuce]

I don't mean to interject stupidity into this discussion.

But, I have seen a Glock with the JP Doublring sights (actually, it was supposed to belong to John, himself, prior to the current owner) ... and, as soon as I read about problems with where to hold and the details of that, I wondered if the Doublring wouldn't be a possible solution.

Two questions on this ...

First, upon reviewing JP's site, I don't see that he offers the front sight (or the pair) for an AR ... just handguns. Does he, in fact, offer them for a rifle ... or are you (kellyn) trying to work with the handgun sights ... and, if so, how'd you get 'em to go on your rifle?

Second, while the Doublring seemed very nice for a handgun, I guess I'm wondering what it'd be like on a rifle shooting at 100yds, 200yds, etc. I would expect that, at longer distances, you might lose the ability to accurately center the target in the front aperture. Then again, I'd expect a typical post-n-notch to be pretty big in front of a 200yds target as well. Any thoughts?

I'm looking to start-up in Tactical, but, if I'm gonna put any special iron sights on, or even not, I'd still be very interested in a resolution to this problem ... beyond adjusting elevation during a string.

[kellyn]

JP sells a detachable front sight for picatinny rail equipped gas blocks. This front sight assembly allows for interchangeable front sights. In seconds you change from a post to an aperture to crosshairs. It is not the JP pistol sight - which I don't care for at all. This sight is in the JP webpage. I cannot recommend it enough. It took John several minutes of high pressure salesmanship to get me to try it but now I'm hooked.

The aperture front sight is perfect for shooting plates since as John Paul describes it "If the plate is inside the aperture, you own it."

My advice to the new 3 gunner is to avoid iron sighted rifle entirely and go the tactical scope route. Irons take more time, training, and dedication. Something few are willing to do. Nothing is more painful (or time consuming) than to watch an iron sighted shooter burn magazine after magazine at a target past 100 yards.