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Wounded Ronin
2/16/2011 11:32am,
Well, in order to try and build the same sort of familiarity, skill and comfort with longarms that I currently have with handguns thanks to regular competition, I have resolved to participate in a local USPSA 3 gun match on Saturday.

However, I learned that there will be a 360 yard rifle shot on a ten inch plate in this competition.

Holy cow! I have hardly ever taken a shot at that distance seeing as I'm used to pistol ranges. How the heck do I make a shot like that?

I plan on taking my A2 style AR 15 since obviously I'll need a lot of accuracy for this event.

A friend helped me to set my irons on that rifle for 100 yards. Just last Saturday he showed me how when shooting atba close target I actually have to aim high because of the position of the sights relative to the barrel.

I surmise that at 360 yards I'd also have to aim high if I'm sighted in for 100 yards. Is that correct? How high should I aim?

If I make the shot I'll be able to tell everyone I learned how to do it on the internet...

Coach Josh
2/16/2011 3:52pm,
It's been awhile since I shot a M16A2 but I can give you some advice, I shot expert in the Corps. You need to practice at the range in the position you plan on shooting first. The A2 style sight adjustments are pretty easy to make. One click here and there and you are on target.

If it is standing I would get my natural aiming down first. I do this by aiming then closing my eyes taking a breath then opening again to see where I was aiming. Then move my front foot left or right and repeat till I would be on target after opening my eyes. Move your body not the rifle.


Clear front sight tip then put the sight in the middle of the blurry target.

Breath
Relax
Aim
Stop
Squeeze

I could shoot a 4 inch group at 500 standing. Which pissed one of my Drill Instructors off.

wetware
2/16/2011 4:05pm,
For a 360 yard shot you'll have to aim low if you're zeroed for 100 yards. If I recall you'll be aiming low about two plates. On silhouettes you aim at the base of the target and hit about center mass. Keep in mind this is all an estimate.

Is the shot resting, standing or kneeling?

Lord Skeletor
2/16/2011 4:19pm,
Depending if you took a standard 25M BZO with your gun or if you sighted it in at 100, it's really going to depend. A 10" plate is a HUGE target...even at 300 yards. You should have no issues. If you have a standard A2 upper (carrying handle style sight), you can copy/print out your standard military-style BZO sight-in target and the ballistics for such weapons (depending of course, on barrel length) are readily available online. You can either hold over/under or you can simply add the requisite number of clicks (remembering of course to undo whatever you "do", when you're engaging targets closer).

Wounded Ronin
2/16/2011 9:38pm,
Wow, thanks for all the info, folks.

I'll do my best this Saturday, maybe aiming low, and then I'll go ahead and fool around learning about zeroing, so hopefully next time I'll feel more confident!

I am not sure if the shot is standing, supported, kneeling or what. But as a n00b, I'll feel no shame in going prone if I have to, as long as that isn't against the rules. :P

Roaming East
2/19/2011 10:07am,
Depending on the ammo, your average civvie 223 is gonna drop about what? 4 inches at 300 yards. If your good at kentucky windage you can simply adjust your POA by that amount without dialing in your sights. Takes knowledge of your rifle and consistancy with your ammo usage though.

hungryjoe
2/19/2011 10:34am,
It's been awhile since I shot a M16A2 but I can give you some advice, I shot expert in the Corps. You need to practice at the range in the position you plan on shooting first. The A2 style sight adjustments are pretty easy to make. One click here and there and you are on target.

If it is standing I would get my natural aiming down first. I do this by aiming then closing my eyes taking a breath then opening again to see where I was aiming. Then move my front foot left or right and repeat till I would be on target after opening my eyes. Move your body not the rifle.


Clear front sight tip then put the sight in the middle of the blurry target.

Breath
Relax
Aim
Stop
Squeeze

I could shoot a 4 inch group at 500 standing. Which pissed one of my Drill Instructors off.

Quoted for emphasis.

Position yourself so your aim is naturally on target.

Breath in, let some out, stay relaxed and squeeze the trigger. Standing, I like to pull off the round as the muzzles lowers onto the target.

10 inch target at that distance is no problem.

Josh,

4" groups at 500 yards standing is some fantastic shooting. Hell, that's good shooting from prone with the M-16.

chainpunch
2/19/2011 11:56am,
With an M16 500 yard shots are impressive period let alone 4'" groups. Beyond 350m the sight post is bigger than the silhouette of a full size man.

Wounded Ronin
2/19/2011 3:44pm,
The competition was called on account of rain. :(

That's okay...I guess it just means I have more time to practice and learn one end of a longarm from another.

Thanks again to everyone for all the advice. I hit an indoor range this morning and attempted the 50 yard zero, since the competition was called.

Knave
2/25/2011 7:05pm,
Are you using a 20" barrel or 14.5/16" ? I'm assuming the latter unless otherwise stated?

Are you using a mil spec rear sight with adjustable windage and elevation, or a back up style/flip up with no elevation adjustment?

For rear sights with adjustable elevation, I personally prefer the revised improved battle sight zero, which requires that you "reset" the click where your elevation bottoms out. By doing so you get a bottomed-out 100 yard (or meters if you prefer that) zero, with the original bottomed-out setting now being a 50/200, while maintaining your normal 300, 400, etc settings. You can find instructions on the net of how to do this, it's easy and just requires an allen wrench. Or find someone local that can show you, or just ask if you have questions about it. It takes almost all the guess work out since your point of aim is generally never off your point of impact by more than about 2 inches assuming your elevation is properly set for the distance.


For non adjustable elevation, I would normally recommend a 50/200 for practical purposes, but if you are specifically having to shoot at 360 yards for competition, assuming you have no targets in about the 100 to 300 range, I would recommend 25/375.

The reason is that with a 25 yard zero, your point of aim and point of impact are nearly crossing at 360 yards. With 50/200, you have more than 10 inches of drop at 360, which is larger than your target. However, pretending I was shooting a competition and for whatever reason did not have a rear sight or optic that was either adjustable for elevation or did not have elevation markings, and if that competition had targets at, let's say 100 yards, 250 yards, and 360 yards, I would probably go with a 50/200 because my point of impact on the 100 and 250 yard targets would be within about 2 inches of my aim on the 10 inch plate, with me having to adjust for 10 inches of drop on the 360. Conversely, under those same conditions with a 25 yard zero, I would have to adjust significantly on two targets, holding low on the 100 (impact about 6 inches higher than aim) and on the 250, with the difference on the 250 being a 10 inch difference between aim and impact.


Wetware, unless I'm reading the post wrong, you have it opposite. A 100 yard zero will drop by about two feet at 360 yards, so you would be aiming very high.



http://www.jesseshunting.com/photopost/data/500/medium/Zerobulletpaths.jpg

wetware
2/26/2011 1:58am,
Wetware, unless I'm reading the post wrong, you have it opposite. A 100 yard zero will drop by about two feet at 360 yards, so you would be aiming very high.
http://www.jesseshunting.com/photopost/data/500/medium/Zerobulletpaths.jpg

Quite possible. I was sleep deprived at the time and didn't really feel like doing the math for it. According to that chart, a 100 yard / 100m zero is practically useless unless all you're doing is shooting at 100 yard targets.

Wounded Ronin
2/26/2011 10:53am,
My twist is 1/9...will that make a difference from what is on that chart?

Wounded Ronin
2/26/2011 10:56am,
Are you using a 20" barrel or 14.5/16" ? I'm assuming the latter unless otherwise stated?

Are you using a mil spec rear sight with adjustable windage and elevation, or a back up style/flip up with no elevation adjustment?

For rear sights with adjustable elevation, I personally prefer the revised improved battle sight zero, which requires that you "reset" the click where your elevation bottoms out. By doing so you get a bottomed-out 100 yard (or meters if you prefer that) zero, with the original bottomed-out setting now being a 50/200, while maintaining your normal 300, 400, etc settings. You can find instructions on the net of how to do this, it's easy and just requires an allen wrench. Or find someone local that can show you, or just ask if you have questions about it. It takes almost all the guess work out since your point of aim is generally never off your point of impact by more than about 2 inches assuming your elevation is properly set for the distance.


For non adjustable elevation, I would normally recommend a 50/200 for practical purposes, but if you are specifically having to shoot at 360 yards for competition, assuming you have no targets in about the 100 to 300 range, I would recommend 25/375.

The reason is that with a 25 yard zero, your point of aim and point of impact are nearly crossing at 360 yards. With 50/200, you have more than 10 inches of drop at 360, which is larger than your target. However, pretending I was shooting a competition and for whatever reason did not have a rear sight or optic that was either adjustable for elevation or did not have elevation markings, and if that competition had targets at, let's say 100 yards, 250 yards, and 360 yards, I would probably go with a 50/200 because my point of impact on the 100 and 250 yard targets would be within about 2 inches of my aim on the 10 inch plate, with me having to adjust for 10 inches of drop on the 360. Conversely, under those same conditions with a 25 yard zero, I would have to adjust significantly on two targets, holding low on the 100 (impact about 6 inches higher than aim) and on the 250, with the difference on the 250 being a 10 inch difference between aim and impact.


Wetware, unless I'm reading the post wrong, you have it opposite. A 100 yard zero will drop by about two feet at 360 yards, so you would be aiming very high.



http://www.jesseshunting.com/photopost/data/500/medium/Zerobulletpaths.jpg

The rifle I'm using was built from the Del Ton A2 kit. It's got a A2 length barrel, chrome lined 1/9 twist, and the rear sight is on a detachable carrying handle. It has knobs on it so I assume it can be adjusted but I haven't done so yet. The adjustments I made so far, with the help of a friend, were on the front sight.

Looks like the bottom line is a 25 yard zero. Well, I can do that easily enough, at an indoor range. Thanks!

tgace
2/26/2011 11:52am,
Buy a magnifying optic.

Knave
3/01/2011 11:31am,
So it's a 20" barrel? I'm assuming it has a 8/3 rear sight?

IMO, for 99% of shooters there's not enough difference in trajectory between a 20" barrel and a 14.5" or 16" to notice, but the 8/3 sight vs. 6/3 sight does make some difference.

Don't mean to insult anyone if this is common knowledge to users here, but on a M16 sight, "from the factory," the sight is generally designed to be bottomed out at the 8/3 mark (or 6/3 for M4's and many or most commercial AR15 sights). Then your original military zero was for 300 meters, and here my memory is a little fuzzy, but I believe the first crossover for that is around 36 yards. Meaning if you bottom out your sight at the 8/3 or 6/3, then zero at 36 yards or so, your 8/3 or 6/3 mark is zero'd for 300 meters, the 4 mark is zero'd for 400 meters, 5 for 500, then on a 6/3 sight you come back around to the 6/3 top'd out and are zero'd for 600 meters, on a 8/3 you get a 7 mark for 700 and top out at 8/3 for 800 meters.

Then you have Santose come up with resetting the rear sight drum to bottom out 2 clicks lower than the 8/3, or IIRC 4 clicks lower than the 6/3. What this does is allow the shooter to zero that new bottomed out click at 50 yards, which gives a 200 meter zero and has alot of practical benefits since you have a point of impact with 2.5" or so of point of aim from 0 to 250 yards. Then the sight is raised from the new bottom'd out spot to the 8/3 or 6/3 which is still a good 300 meter zero, the 4 is still a 400, etc.

This was originally used with 55gr M193 ammo, and therefore the same trajectory doesn't apply exactly for other rounds which has to be considered if you use different bullet weight than that. Also note that the 50/200 is 50 yards/200 meters though often gets confused or taken for granted as a 50yard/200yard, which is close enough I guess.

So my point is that how you zero may depend on your purposes.

Assuming you are using 55gr ammo, that chart will be close enough to get you on target, and you can make minor adjustments from there if need be.


If you zero your 8/3 marking for 25 yards by bottoming out and then adjusting the front sight, your 4, 5, 6, 7, and 8 marks no longer really mean anything because your bottomed out 8/3 will be a 375ish yard zero rather than a 300 meter zero. This isn't really a problem if you are only worried about the competition shoot distances, and plan on using the 25 yard zero (with crossover at 375ish yards) to aim for point of aim/point of impact on the 360 yard target, and use a little guess work for holding low on targets closer than that.

Or, the really easiest thing is to have a magnified optic with bullet drop markings for a M16 with 55gr ammo, which may not be allowed in the competition?

Devil
3/01/2011 2:18pm,
I'm betting you'd be shooting from a sitting, kneeling or prone position.

Hitting a 10" plate from 360 yards from the standing position with open sights is not an easy shot.