100 m = 109.361 yrd

[Shrinkmd]

I splurged on the ACOG, and now its time to zero it at the range! We have a 50 M, 50 yd, and 100 yd place for targets (and 200 and 300 yd, but that's another story)

Should I just zero it at 100 yd (which is only 91.44m) and figure it is within the tolerance of whatever ammunition I'm using? After all, your average AR with M193 is 2MOA on a good day, right? So the calibration should be ok?

Sure does look sweet sitting up there! I didn't realize how small it was.

Is it worth getting an extra hole drilled in my carry handle, or do they hold zero and stay secure just with one screw? It seems really snug on there, but then again I haven't shot it (or dropped it) yet.

 

[Jim Watson]

If you are going to be shooting at 100 yards then zero at 100 yards.

If you are going to depend on one of their trick reticles for longer ranges, you are just going to have to shoot the gun and see how close the graduations are.

In the meanwhile, you can run through the ballistics calculations at
http://www.eskimo.com/~jbm/calculations/traj/traj.html
or on Hornady's site and see what effect the difference between a metre and a yard has on your application.

 

[possum]

there is alot of info on ar15.com when it comes to the acog, and how to zero different models, on different model ars with different loads etc. there is a thread dedicated just to that. check out ar15.com

 

[30Cal]

The difference between yds vs meters with respect to your elevation knob isn't going to matter until you get out to 300+yds when the bullet really starts to drop.

 

[Zak Smith]

You're pretty much correct that differences in load and barrel and environment will subsume the difference between 100m and 100 yards.

I zero my ACOGs at 100 yards, top of donut, and then figure holdovers from there on out.

 

[Shrinkmd]

I have a 20" barrel, and according to Trijicon their reticle is based on a 20" barrel shooting 55 gr m193 spec ammo. So I was hoping that 100 yd zero would be "close enough". I will have to try out the 200 and 300 meter settings and see how far off they are at 200 and 300 yards.

Either way it should be loads of fun. I know I need to re-zero my irons as well, since having something mounted on there throws it off (so I have read)

 

[Eroc]

there is alot of info on ar15.com when it comes to the acog, and how to zero different models, on different model ars with different loads etc. there is a thread dedicated just to that. check out ar15.com

I LOVE Arfcom!

 

[Bartholomew Roberts]

There is virtually no difference in zeroing at 100m vs. zeroing at 100yds.

With an ACOG, you will see a difference past 300yds because the ACOG is set up in meters and most ranges are set up in yards. The drop will still be correct (assuming same height over bore, muzzle velocity and proper zero at 100yds) but if you use the 400m crosshair on a 400yd target, the rounds will hit high. This has nothing to do with the fact you zeroed at 100yds though.

The best way to do this (if shooting at IDPA or silhouette targets) is to remember that each crosshair is about the width of a silhouette target at that range - so just pick the crosshair that best matches the silhouette and that is the crosshair to use.

 

[FlyinBryan]

dont drill your carry handle

you will be surprised how sturdy it will be with one.

dont use plyers on the thumbwheels either. they will hunker down very nicely if you just get them as tight as you can by hand.

(well, ok, maybe a little on the rail nuts, but not under the handle.)

 

[Zak Smith]

Think about it this way... what is the difference in elevation from 100 to 109 yards? Figure that in MOA and that'll be the error in your zero. In other words, almost 0.

 

[boilingleadbath]

Running "Remington Shoot!", with a 2.5" sight height (I don't actually have an AR with optic to measure, so that's a guess)... I find that to generate a 109 yard zero on a 100 yard target you should put the point of impact .02" below center.
(Remington 55gr fmj)

...essentially, no difference.