80 yard sight-in question

canislatrans54

canislatrans54

New member
Hey all! /ubbthreads/images/graemlins/grin.gif

My question is: Using .223 caliber, 55gr. factory PSP, muzzle @ 3240'...if I want a 250 yd. "zero"...how high should I be hitting @ 80 yds.? /ubbthreads/images/graemlins/confused1.gif /ubbthreads/images/graemlins/confused1.gif

Now the reason I ask:
As soon as I (get a day off, & it stops raining), /ubbthreads/images/graemlins/crazy.gif I want to go to the nearest shooting range to play with my guns. /ubbthreads/images/graemlins/grin.gif
This range is only set-up for a maximum of 80 yds., though. /ubbthreads/images/graemlins/frown.gif
I want to check my "zero", as well as do some shooting off the sticks.
For practice & fun. {ya know, pill bottles/caps, playing cards, ect.} /ubbthreads/images/graemlins/smile.gif
I haven't checked "zero" in a couple years. /ubbthreads/images/graemlins/smiliesmack.gif
When I had, I had it shooting 3.5" high @ 100 yds. /ubbthreads/images/graemlins/blush.gif
I'm basing the 250 yd. "zero" on the fact that I rarely shoot farther than that, but don't want to have to worry about "holding over" @ around 250. /ubbthreads/images/graemlins/grinning-smiley-006.gif
Truthfully, since I don't reload, most of this velocity/trajectory stuff goes over my head. Hence, the reason I'm asking people I trust! /ubbthreads/images/graemlins/grin.gif
THANKS! /ubbthreads/images/graemlins/cool.gif
 
80 yards is still in your mid-range trajectory.

If you have the information of impact at 50 yards and 100 yards, all you have to do is interpolate the bullet drop to 80 yards.
Then you can pretty much sight based on that calculation to 250.

I have a .223 set for long range. 300 yard zero...& it's about 3" high at 100.

Too high for my liking on a coyote calling rig....That one is sighted dead on at 100 yards.
 
Will, based on the info you provided, when zeroed at 100, you will still be ZERO at 80. I had to guess on the BC of the bullets since you didn't say the brand, but it should be close. I used a Hornady SP that has a BC of .0235

Go here:

http://www.biggameinfo.com/BalCalc.aspx

and just fill in the blanks. /ubbthreads/images/graemlins/wink.gif

All the info you need is muzzle velocity, ballistic coefficient, and the distance that you want to zero. It does the rest for you.

Hope that helps.

Steve.
 
Sorry....just saw that you said you wanted a 250 yard zero. /ubbthreads/images/graemlins/smiliesmack.gif

At a 250 yard zero, your rifle should be 2.1" high at 80 yards. It will be 2.6" high at 100 yards. BUT...it will be 3.0" high at 150 yards.

When you use the calculator, set the range interval option to 10 and you'll get a better overall picture of what you're doing.

Steve.
 
Will,

What factory ammo are you using? Let me know and I will plug the numbers into my Sierra Infinity Ballistic program with all the variables and let you know. Depending on manufacturer, the bullet may have a slightly different ballistic coefficient. It probably won't matter too much, but we might as well get all the numbers correct right off the bat.
 
Quote:
scope height above bore measurement needed.



YEP. I just "assumed" it was 1.5" on a bolt gun. /ubbthreads/images/graemlins/confused1.gif

Of course if it's an AR......I'm WAY off. /ubbthreads/images/graemlins/laugh.gif
 
Best advice I can give is.....find a different place to shoot. No matter what dope is given here and by whom, until you shoot your rifle at the distance you want it zeroed for, you'll still be guessing.
 
Jimanaz...very true. /ubbthreads/images/graemlins/grin.gif However, the only other option I have is to shoot out in my dad's pasture...& with cattle in there, that's NOT an option. /ubbthreads/images/graemlins/frown.gif

Sorry guys, I knew I would forget things: /ubbthreads/images/graemlins/smiliesmack.gif
#1...the brand is Black Hills {Blue}
#2...scope height is 1.75", 3x9x50 @ 64mm rings (I know, I really should lower it), on a Stevens 200

#3...time to show my ignorance...What is "ballistic coefficient"??? /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif

If I'm reading correctly, with it the way I have had it...3.5" high @ 100 yds...man, it's no wonder I could hold center-of-coyote @ 250+ & still hit them!! /ubbthreads/images/graemlins/shocked.gif /ubbthreads/images/graemlins/cool.gif Interesting! /ubbthreads/images/graemlins/smile.gif /ubbthreads/images/graemlins/smile.gif
 
Here you go Will:

ZERO @ 250 yards:

POI @ 50 = +0.8"
POI @ 80 = +1.9"
POI @ 100 = +2.4"
POI @ 125 = +2.9"
POI @ 150 = +2.9"
POI @ 175 = +2.7"
POI @ 200 = +2.2"
POI @ 225 = +1.3"
POI @ 250 = ZERO
POI @ 275 = -1.7"
POI @ 300 = -3.9"
 
What is "ballistic coefficient"???

The ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. It is inversely proportional to the deceleration--a high number indicates a low deceleration.

Simply stated, the ballistic coefficient is a measure of how well a projectile behaves in air.

A round ball has a LOW BC, an arrow has a HIGH BC. The higher the number, the better it "flys" before it bleeds off velocity. /ubbthreads/images/graemlins/wink.gif
 
Jimanez gave you some good advice. However, this is what my ballistic software spit out for ya.

Parameters:

Air Temperature - 40 degrees F
Elevation - 1270 feet for Saline County, Kansas
Muzzle Velocity - 3240 fps
Scope height - 1.75
Bullet - Black Hills 55 gr. PSP


At 80 yards you should be 1.9" high.

At 100 yards you should be 2.43" high.

At 150 yards the bullet is at its highest point of 2.95".

At 200 yards you should be 2.23" high.

At 250 yards your dead on and at 300 yards your 3.78" low.

I hope this helps. /ubbthreads/images/graemlins/grinning-smiley-003.gif
 
Quote:
......and at 300 yards your 3.78" low.




OH CRAP!!!!!!! /ubbthreads/images/graemlins/shocked.gif

Either my or your calculator is off by .12" /ubbthreads/images/graemlins/shocked.gif

/ubbthreads/images/graemlins/laugh.gif . /ubbthreads/images/graemlins/laugh.gif . /ubbthreads/images/graemlins/laugh.gif
 
Thanks guys...all of you!! /ubbthreads/images/graemlins/ooo.gif /ubbthreads/images/graemlins/ooo.gif
I knew I could count on getting the proper info! /ubbthreads/images/graemlins/grinning-smiley-003.gif

(and I think I'll leave all that "ballistic coefficient" stuff to you guys that deal with it a lot...my head's starting to hurt from having to think hard enough to understand it.) /ubbthreads/images/graemlins/smiliesmack.gif /ubbthreads/images/graemlins/laugh.gif /ubbthreads/images/graemlins/laugh.gif /ubbthreads/images/graemlins/laugh.gif
 
Quote:
Quote:
......and at 300 yards your 3.78" low.




OH CRAP!!!!!!! /ubbthreads/images/graemlins/shocked.gif

Either my or your calculator is off by .12" /ubbthreads/images/graemlins/shocked.gif

/ubbthreads/images/graemlins/laugh.gif . /ubbthreads/images/graemlins/laugh.gif . /ubbthreads/images/graemlins/laugh.gif



Dang I know! I don't know what Will should do now. Hey Will, you better hold in between the two at 300 yards just to be on the safe side. /ubbthreads/images/graemlins/laugh.gif /ubbthreads/images/graemlins/laugh.gif /ubbthreads/images/graemlins/laugh.gif /ubbthreads/images/graemlins/tongue.gif /ubbthreads/images/graemlins/tongue.gif
 
You guys are too funny.

I remeasured my scope height...found out it's actually closer to 2", so that will change things some.
I looked over an entire Black Hills box, and couldn't find where it says what the coeffiecent is...how did you guys know?...and what is the number, please?
{I was going to "redo" the above range finding, taking into account the remeasured height, but didn't know how to find the coeffiecent number for the scale.}
Thanks!
 
Will, I actually used the "SWAG" method........

Some
Wild
Arsed
Guess.......... /ubbthreads/images/graemlins/laugh.gif

Actually, I used the BC from a Hornady 55grSP as it is listed in the loading manual. It should be very, very close. The BC I used is 0.235
 
Hey guys, what barrel length are you basing this on. /ubbthreads/images/graemlins/confused1.gif Would like the poa on this with an AR15 16" stainless bull barrel. /ubbthreads/images/graemlins/confused1.gif Sorry to jump in on this, but would like to know on my rifle also. /ubbthreads/images/graemlins/grinning-smiley-003.gif Thanks, Tony
 
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