Sighting in rule of thumb

[Lost Lake]

It's been a lot of years for me fellas, but I seem to remember a rule of thumb for sighting in a 5.56 / AR / M16.

Is it sight in at 25 yards and it will be back on at 300 yards?
And if I remember right the bullet won't rise more than 3" in between.

This was for standard ammo, M193. Tracers were all together different I think.

 

[cyphertext]

From the trajectory charts I have seen, if you zero at 25yds, you will be back on at 375yds, or so. You still have 10" in rise...

 

[Lost Lake]

I see that now cyphertext. I found a couple of charts.

Yes with the standard 2.5" height the sights are above the bore, I think I want to be sighted in at around 50 yards. That will put the bullet back on target at about 200 yards again and the round should always be within about 2" everywhere in between.

I just have to remember to hold over at distances closer than 50 yards.

 

[cyphertext]

Yes, that is a popular sight in, since it keeps the trajectory flatter, and a lot of us don't have access to ranges that are much longer than 200 yards.

I have my red dot set up for the 50 yard zero for the same reason.

Did you see this page? Lots of chart data...

AR-15 Trajectory Graphs - AR15.Com Archive

 

[webfarmer]

This is great info - thanks! I have a new one to sight in on its way.

 

[rbuzz]

There's a really good video on youtube that does an excellent job of explaining the process of sighting in your iron sights. The video suggests using the Army method of zeroing in your AR by using the 25 meter method. How to Zero your AR15 / M4 / M16A2 Platform: Mechanical Zero & the 25m Target - YouTube

 

[zotzer]

That's what I do, rbuzz...use the 25m army sight-in target. It's really easy.

 

[rbuzz]

Instead of buying targets, print your own. For a source of several downloadable targets, including the 25m M16/AR15 Army check out this site
Print your own targets
It seems like this is one item that I always forget to keep in stock and I hate the hassle of making a special trip just to buy some paper targets.

 

[Lost Lake]

For a 25 yard site in you have to adjust your rear sight elevation so when you back it down it will be sighted in at 50 right?

 

[cyphertext]

For a 25 yard site in you have to adjust your rear sight elevation so when you back it down it will be sighted in at 50 right?

Not sure I understand your question, but I'll take a stab. When you sight for 25 yards, you will not be zeroed for 50. You will shoot high at 50, 100, 200, so you have to remember to hold under. You can't turn the elevation knob down further, because unless you have modified your rear sight, it should be bottomed out at the 300 yard mark. You flip to the large objective and aim low for 50 yards.

 

[Lost Lake]

I believe to sight in at 25, you should adjust the elevation on the rear handle mounted sight to a specific setting. It's been about 30 years for me so I don't remember this, but then after you sight in you'd readjust the rear sight which would put you really close at 50.

I think you really want to be sighted in at 50 instead of 25 yards. At a 25 yard zero you will hit about 9 inches high at various distances between 25 yards and 325 yards, whereas if you zero at 50 yards you will be within about 2" of point-of-aim between 50 and 200 yards.

That's why I believe by adjusting the rear elevation prior to sighting in at 25 yards, then adjusting it back you will be sighted in at 50 yards.

If I'm making no sense at all I will repost with specific numbers and the procedure....

 

[Four T5]

There's a really good video on youtube that does an excellent job of explaining the process of sighting in your iron sights. The video suggests using the Army method of zeroing in your AR by using the 25 meter method. How to Zero your AR15 / M4 / M16A2 Platform: Mechanical Zero & the 25m Target - YouTube

Excellent info. Thanks for posting the link.

 

[cyphertext]

I believe to sight in at 25, you should adjust the elevation on the rear handle mounted sight to a specific setting. It's been about 30 years for me so I don't remember this, but then after you sight in you'd readjust the rear sight which would put you really close at 50.

I think you really want to be sighted in at 50 instead of 25 yards. At a 25 yard zero you will hit about 9 inches high at various distances between 25 yards and 325 yards, whereas if you zero at 50 yards you will be within about 2" of point-of-aim between 50 and 200 yards.

That's why I believe by adjusting the rear elevation prior to sighting in at 25 yards, then adjusting it back you will be sighted in at 50 yards.

If I'm making no sense at all I will repost with specific numbers and the procedure....

Watch the video that is posted. You will see that when he sets his rear sight to 6/3, the rear is bottomed out and he makes elevation adjustments at the front sight, for sighting in purposes. Then out on the range, if he goes to 400 yards, he would turn the wheel to 4, 5 for 500, etc. Anything between 25 and 300, you will have to use hold under.

 

[crofoot629]

50/200 yard zero makes more sense to me.

I sight my hunting rifles in at 200 yards also. ymmv.

Emory

 

[Lost Lake]

Watch the video that is posted. You will see that when he sets his rear sight to 6/3, the rear is bottomed out and he makes elevation adjustments at the front sight, for sighting in purposes. Then out on the range, if he goes to 400 yards, he would turn the wheel to 4, 5 for 500, etc. Anything between 25 and 300, you will have to use hold under.

Yeah, but there's too much hold under at 200 yards.

I think you set the rear sight off a bit, then bump it back when you are sighted in at 25. I don't have those sights so I can't look at it. What I'm saying is you never really want to be sighted in at 25, you just set the sights to get it there, then back them off again.

I have the Troy rear so I'm sighting in at 50. The Troy doesn't have an elevation adjustment. If I wanted to use a 25 yard range, I would be low at 25 yards, maybe an inch or an inch and a half, I can't remember.

I'll have to look it up and report back...

 

[cyphertext]

Yeah, but there's too much hold under at 200 yards.

I think you set the rear sight off a bit, then bump it back when you are sighted in at 25. I don't have those sights so I can't look at it. What I'm saying is you never really want to be sighted in at 25, you just set the sights to get it there, then back them off again.

I have the Troy rear so I'm sighting in at 50. The Troy doesn't have an elevation adjustment. If I wanted to use a 25 yard range, I would be low at 25 yards, maybe an inch or an inch and a half, I can't remember.

I'll have to look it up and report back...

I think what you may be thinking of is when you are sighting in with the 20" barrel on the M16. When zeroing at the 25m, you set it on Z which is a couple of clicks up from 3. But for the M4, you bottom it out at 3. Since our rifles are 16" barrels and not 14.5", I would assume that is why we are not back on at 300, but more like 370 per the charts, plus the fact that it is a 25m zero and we tend to measure in yards.

I think the 50 / 200 yard sight in is better for most civilian applications. The trajectory is flatter and I probably can't claim self defense if I am making hits at 300m or greater.

 

[Lost Lake]

Like I said, I don't have an adjustable elevation on the rear sight.

The military likes to sight in at 25 yards or meters because the troops can actually hit the dang target. But they don't want the gun sighted in for 25 yards because the trajectory is so bad.

Therefore if you crank the rear sight up and sight at 25 yards, then drop the rear sight back down, you will be sighted in at 50 yards without having to actually make that longer shot.

 

[cyphertext]

Like I said, I don't have an adjustable elevation on the rear sight.

The military likes to sight in at 25 yards or meters because the troops can actually hit the dang target. But they don't want the gun sighted in for 25 yards because the trajectory is so bad.

Therefore if you crank the rear sight up and sight at 25 yards, then drop the rear sight back down, you will be sighted in at 50 yards without having to actually make that longer shot.

Please tell me you are joking...sighting in at 25 meters because the troops can hit the target? Were you ever actually in the military?

300m has been the traditional battle sight zero for decades. The military zero's at 25m due to that being the first point that the bullets trajectory crosses the line of sight, and then crosses again at 300m, with the proper ammo and barrel length. It is easier to get on paper at 25m, and shorter walking, but once the rifle is zero'd at 25m, the battle sight zero is confirmed at longer yardage. For anywhere between 0 - 200m, you use the large aperture. The large aperture is on a different plane than the small aperture, thus changes your line of sight, effectively lowering the hit on target. However, you still have to aim low and know your hold under.

Using the 25m / 300m sight in procedure, there is no elevation setting at the rear sight that will put you on at 50 yards. It really is that simple. If you are using a Troy sight that does not have an adjustment for distance at the rear sight, this procedure does not apply. It is only applies for A3 and A4 sight systems.

 

[wild_weasel]

I just sighted in my son's Sport at 25 yards using a USGI carry handle / sight. The removeable handle has a 3/6 and a z three clickes away, while the fixed handle has a 3/8 setting. With 14.5" and 16" barreled rifles you use 3/6 (bottomed out) with the front post level with the A frame. On a 20" rifle you would set the rear sight to z to zero at 25 yards then return to 3/6 or 3/8 to be zeroed at 25/300 yards. I did this with my son's Sport and we were pretty close to point of aim at 25 yards our first 3 shots and were able to zero the rifle in 12 shots using a 25 yard M4 target and 55gr ball ammo, With either Sport it is easy to keep all shots within 4cm at 25 yards, on averabe I can keep my shots inside of 2cm, but my eyes are nto what they used to be.. Since most of our shooting is at a local indoor range that allows high power rifles the 25/300 zero works great. Using the iron sights we are almost as accurate as when using my Sport with an AimPoint Pro installed using a 25/300 1/3 cowitness, if you wear glasses it is hard to beat a good quality red dot sight.

 

[Lost Lake]

Please tell me you are joking...sighting in at 25 meters because the troops can hit the target? Were you ever actually in the military?

300m has been the traditional battle sight zero for decades. The military zero's at 25m due to that being the first point that the bullets trajectory crosses the line of sight, and then crosses again at 300m, with the proper ammo and barrel length.

Ha ha ha ... Yup, I was in the military, and scored expert every time... I just can't remember the settings on the old non-removable handles the sights were mounted on.

The bullet will NOT be sighted in at 25 and 300. That's not a true statement. It would be more like 25 and 375. That's why the pre-adjustment for the sights when you are shooting at a 25 yard/meter target. You do NOT want to ever sight in at 25 yards actually. So you change your sights before you sight in and then change them back for a 300 yard target.

And yes, the 25 yard target is so troops can hit the dang thing. And you can see where it hit. At 300 yards (which we used to shoot also) you need a spotter at the target to record your hits.

Okay, back on track. Whatever you do, don't sight in at 25 yards because the next point your bullet comes back down from the stratosphere will be around 375 yards. At 200 yards your bullet will be about 9 inches above the target. If you want to use the old military method of sighting in at 25 yards, you must adjust your rear sight 3 clicks PAST the 300 mark. After sighting in, readjust the rear sight to the 300 mark and you will be sighted in at 300 yards. (You will still be quite high at 200 yards, but not as bad as if you didn't adjust past the 300 mark before sighting in. )

Here's what a M-193 load in a 16" barrel would graph like....