Maybe you rifle guys can help me


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tnieto2004
October 25, 2008, 04:11 PM
So today I went to the range to sight in a AR-15 (In .223) I have had for a while. I was only able to shoot on the 25yrd range (Due to the amount of people on the 50 and 100yrd ranges). It was dead on and I was putting most of them through the same hole. I am wanting to know if I am dead on at 25yrds, what will I be looking like (ballistics of course) at 50 and 100 yrds? I was shooting 55gr Remington UMC. Thanks for any help you can offer.

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goon
October 25, 2008, 04:20 PM
Don't know off the top of my head. Check Remington's website and use their ballistics page to check their short range trajectory tables.

KW
October 25, 2008, 07:58 PM
Typically a 25 yard zero with an AR is going to put you around 2" high at 50 yards, 4" or so high at 100, and nearly 10" high by 200. It won't cross your sight plane again until past 400 yards! That kind of arc makes it pretty hard to hit stuff. A better method would be a 50 yard zero, which will put you about + or - 2" from the muzzle out past 250 yards. Check out http://groups.msn.com/TheMarylandAR15ShootersSite/zeroingmethods.msnw. You'll find a lot of information there on zeroing your AR.

MT GUNNY
October 25, 2008, 09:23 PM
Are you using standard AR open sights or a scope?

If a scope remember, your sight line is high above the bore. shooting small critters up close with a 100 Yard zero you will shoot under them.

rangerruck
October 26, 2008, 12:45 AM
I agree with both the above, a 25 yd zero with no scope, can still be pretty high at 150 yds, but I am not sure about the 10 inches, I could def see over 5 though. with a scope, on at 25 yds, will def get you 10 inches above, down at 150 or so. I would shoot about .5 inches low, with no scope, at 25 yds. this will give you a fairly flat traj all the way out to about 300 yds. With a scope, I would put it more like 3 inches low at 25.

Chuck Dye
October 26, 2008, 03:23 AM
What is the sight height above bore?

My software shows a UMC 55gr FMJ with a muzzle velocity of 3240 and ballistic coefficient of 0.101. Take those numbers and your sight height to the Norma website (http://www.norma.cc/default.asp?Lang=2#), bring up the ballistic calculator, and use the "Define your own bullit (sic)" function. That should get you fairly close to the real world. At least you will have a starting point for your own tests.

Chuck Dye
October 26, 2008, 03:39 AM
I went searching for a sight height. There is actually a http://ar15zeroing.com/ as well as a lot of other info if you search on "ar-15 sight height above bore." Removable sights are listed as 2.6" above bore, fixed handle sight as 2.8".

My software predicts a 2.6" HOB zeroed at 25 yards to zero again just shy of 280 yards and peak at about 8.6 inches high at about 170 yards.

The 2.8" height yields a far zero at 290 yards and midrange height of about 9.8" at 190 yards.

As always, such calculations are only jumping off points for real world testing.

tnieto2004
October 26, 2008, 12:13 PM
I'm sorry for the lack of information, I am using a 3-9x scope on a flat top with 1" rings.

rangerruck
October 26, 2008, 01:45 PM
off of a flat top, you are proly ver close to 1.75 to 2 inches above center of bore line. I would go with being 2 inches low at 25, this should give you a decently flat shooting area, from muzzle to about 250 yds. with maybe a 5 inch rise in between..

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