.223 question: installing a scope at 25yd range


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TCW
January 3, 2003, 07:44 PM
Hi!
I have a mini-14 (.223) and only have access to a 25 yd shooting range (indoor). Approximately how far above or below the bullseye should I set it up at 25 yds if I want it to be zero at 100 yds?

I will get to a rifle range later this month.

Thanks!
TCW

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cratz2
January 3, 2003, 10:15 PM
Be sure you can shoot a high powered rifle at the indoor range first... Dead on at 25 wouldn't be a bad place to start. I think wth 55 Gr ball in an M16/AR15, 42 yards is the same as 200 yards.

Archie
January 4, 2003, 12:43 AM
is a great place to start.

What you need to do is to research for a ballistics table that shows registration for both 25 and 100 or 200 yards.

Combine that with the actual muzzle veocity of your rifle and ammo; and you are ready.

Still, the 25 yard mark will get you very close to where you wish to be.

Nero Steptoe
January 4, 2003, 10:24 AM
"Still, the 25 yard mark will get you very close to where you wish to be."

Good advice by all; however, considering the rifle involved, it'll be hard to tell at 100 yd. whether you've messed up or not.

cratz2
January 4, 2003, 11:03 AM
considering the rifle involved, it'll be hard to tell at 100 yd. whether you've messed up or not.


:D

TCW
January 4, 2003, 01:14 PM
I live in PRK, guys. No evil ARs, AKs, etc.:rolleyes:

Chuck Dye
January 4, 2003, 03:11 PM
Without the muzzle velocity and ballistic coefficient, the answer is pretty broad. Go to

http://www.norma.cc/htm_files/javapagee.htm

with the specifics of your chosen round and play with the define your bullet option. Bear in mind that your mileage may vary!

Ironbarr
January 4, 2003, 06:59 PM
Along with everything else recommended, you might read http://groups.msn.com/TheMarylandAR15ShootersSite/zeroingmethods.msnw - barrel length may affect the 3/8-inch below call.

-Andy

P95Carry
January 5, 2003, 01:27 AM
IIRC, to cope with the parallax, with a scope particularly . about 1" below center will help. Iron sights - I guess POI is not a bad start.

With the flat trajectory of 5.56 anyways . hard to go far wrong even with a zero at 25!!

redneck2
January 5, 2003, 07:42 AM
I zero all my scopes at 25 yards. Usually puts you back on somewhere between 100 and 200, but (as always, depends)

on speed of the bullet, and height of the scope above the bore

if you've got a big objective lens (and resulting higher mounting), the bullet will rise more and cross again further away

geekay
January 5, 2003, 08:01 AM
Zero @ 25 is very close to zero @ 200; less than 1/4'' variance. Now for 100 go down six or seven clicks (assuming 1/4'clicks) and Hey Presto, you're there. If you use the same load for the whole range this is the good oil regardless of bullet weight BUT I can't help you past 200.

P95Carry
January 5, 2003, 12:39 PM
Just occured to me ....... this is essentially only good for elevation IMO ...... I can think of many instances where windage (even in calm conditions) needed tweaking for 100, when seeming spot on at 50 say ....... but generally, apart from serious accuracy requirements ... the 25 trick is a great start.

I know if I push my normally 50 yd zero'd .22 to 100 .. I not only have to raise aim to a point about 6 plus inches higher but . shots always drift a tad to right.

sasnofear
January 11, 2003, 03:46 PM
SIMPLE: DRIVE TO A 100YRD RANGE!

Art Eatman
January 11, 2003, 04:20 PM
A broad range of cartridges and low-mount scopes will be pretty close to "on" if you zero at 25 yards. In general, you wind up roughly two to three inches high at 100 yards, and somewhere around dead-on to an inch or so high at 200. And, around six inches low at 300, roughly. This is certainly close enough to avoid wasting time when you get to a range with 100-yard capability.

I always sighted my Minis for about 1.5" high at 100, putting the bullet dead on at 200. Worked fine for jackrabbits and coyotes.

Once I get a rifle set up for a 200-yard zero, I don't ever mess with the scope again, absent impacts or stock-warp or some such. Even playing on my 500-yard range, it's easier to hold over than to worry about resetting the scope. :)

Art

TCW
January 13, 2003, 01:06 AM
I'm using a fairly high-mounted 35mm red dot. I figure I should set it at about an inch low at 25 yds. Would that put me pretty much on at 100-150 yds?

Art Eatman
January 13, 2003, 06:56 PM
TCW, I guess that's a definite "probably". :)

IMO, anything you do at 25 yards is just sorta "rough-in", and needs checking "for real" at a 100-yard range.

I have found that if everything works to suit at 100 yards, it will provide good hunting accuracy out to 400 or 500.

Art

Redlg155
January 13, 2003, 07:56 PM
Depends on what your definition of "High" is. :D

Once you get a rough zero go ahead and sight it in at 100. Then recheck at 25 to see how much of a difference you have.

I wouldn't worry about too much long range shooting. With your red dot you might get "minute of pie plate" at 100 yards. It's kinda hard to do any accurate shooting when your dot size is anywhere from 3 to 12 MOA.

Good SHooting
RED

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