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View Full Version : How to change zero from 25 yards to 100 yards


Doctawho
04-14-2012, 9:23 PM
I've zeroed my AR-15 at my local indoor range @ 25 yards. Is there an easy way to just make a few clicks of adjustment and get pretty close to my zero for 100 yards?

Ive got a standard AR flat top with a VX-3 1.5-5 in an American Defense QD mount.

Prc329
04-14-2012, 9:26 PM
Chrono the ammo your gonna use and get a ballistics app. Put in you zeroed at 25 yards and it should give you your dope to what ever distance you like.

NiteQwill
04-14-2012, 9:27 PM
Why don't you zero at 50 since the trajectory will remain the same to 250? There really isn't any reason to zero to 100 unless you're shooting at that distance consistently (CMP matches, etc.).

The only way to zero at 100 is to actually do it. Unless you have a standard A2 rear sight.

Doctawho
04-14-2012, 9:35 PM
My calculator says 3.0 inches. Is that 3 inches up or down? I'm freaking confused.


Chrono the ammo your gonna use and get a ballistics app. Put in you zeroed at 25 yards and it should give you your dope to what ever distance you like.

Sosoomi
04-14-2012, 9:42 PM
Actually it depends on a number of factors... Elevation, humidity, ammo... I use Nikon's Spot On app on my iPhone and iPad.... amazing little program...

coy80176
04-14-2012, 9:58 PM
As one of the others already stated, the POI at 50 is the same at 250 (which are the "left and right sides of the arch") and at 100 yds you're on the top of the arch...

if you are zeroed at 25 yds, then at 100 yds the POI will be 3" high....so adjust your scope elevation to "bring it down"

check out this vid, he zeros for 300 yds, by shooting at 100 yds and hitting 3.5" above the bullseye:
http://www.youtube.com/watch?v=D4v0hEbW2OM

If i'm wrong, cuz I could be...I've been drinking;), I'm sure the others will keep me honest

Cheers:cheers2:

Dark Mod
04-14-2012, 10:12 PM
You should probably just zero it at 100 yards

ExtremeX
04-14-2012, 11:22 PM
I do this with almost every rifle I own since all I have is a 25 yard range near me... Zero for 100 (or whatever) at a 25 yard range, and I'm pretty much dead on at 100. Few times I didn't even need to fine tune it at 100.

First off, get or make a drop chart based off ur rifle, ammo, sight height, all that jazz.

Set the drop chart to a 100 yard zero. At 25 yards you should be shooting low (how low depends on your setup). With a 3" sight height im usually about -1.3 to -1.5" low at 25 yards.

Get a ruler, or make your own targets... shoot at center until your POI meets your drop for 25 yards with a 100 yard zero.

Done

Assuming you don't screw this up, its worked every time for me.

MrOrange
04-15-2012, 12:02 AM
Why don't you zero at 50 since the trajectory will remain the same to 250? There really isn't any reason to zero to 100 unless you're shooting at that distance consistently (CMP matches, etc.).

The only way to zero at 100 is to actually do it. Unless you have a standard A2 rear sight.

Is that the deal for carbines? When I was in we zeroed our A1s at 25m, and were told the next cross over was at 250. This was with the 55g stuff.

Interesting tidbit: When I first zeroed my .308 bolt gun I shot at 25 yards to make sure it wasn't wildly off, and that turned out to be right on at 100.

ExtremeX
04-15-2012, 12:14 AM
Is that the deal for carbines? When I was in we zeroed our A1s at 25m, and were told the next cross over was at 250. This was with the 55g stuff.

Interesting tidbit: When I first zeroed my .308 bolt gun I shot at 25 yards to make sure it wasn't wildly off, and that turned out to be right on at 100.

I posted this in another thread but ill post it again.

What you are referring to is called the improved battlesight zero... popular with the RDS crowd.

Its actually closer to 50/200 yard crossover. Depending on the load and sight height they should meet around there.

The whole point of this is it give the round a reasonably flat trajectory across a realistic usable range. If you are shooting a man sized target, couple inches in either direction isn't going to be a big deal across the CQB to 300 yard range. If you are shooting soda cans improved battlesight zero might not be for you. It depends on the optic and application, but I still use it for all my red dots.

If you are a precision shooter, its a different story. I prefer to dial in correction since Im more of a target shooter.

Speedpower
04-15-2012, 12:36 AM
http://dl.boxcloud.com/bc/1/61be3cd28515407c9c29453c2fbb0b5f/oenreawNV0lbLoTBUAqgf6iVSAC5uVZfKQyzM1tPCjGpW8LXcz KCxywEw2BbUs_Z753_UqXiVYi_9SGCU7Tucg,,/c0156d1a3988de5ce02554459817af51/

Saym14
04-15-2012, 1:03 AM
zerofor 50 yds is the best IMO

smittty
04-15-2012, 1:52 AM
I agree with the others that say to USE A 50 YARD ZERO