Point of Aim vs Bullet Trajectory

[gpurp]

I sighted in my new deer hunting rig this morning. Weatherby .308 vanguard, Trijicon Accupoint 3x9, Talley medium rings, Hornady Whitetail 150gr interlocks. I was limited to 60 yard shots but was grouping nicely 1" above point of aim. I don't have any ballistics software and don't know how to calculate this out. Can someone tell me if this is anywhere near a 200yd zero? That's about the max range I'll be shooting come this fall.

 

[Shaky]

(Assuming 1" high at 60 yards)

Should be good to 200 for boiler room shots.

 

[Haxby]

You might be 1.5" high at 100 and 1.5" low at 200.
But probably not, and there's no way to know for sure without shooting it.

 

[Vern Humphrey]

On my ballistic computer, you should be good to 350 yards.

 

[jmr40]

That SHOULD be zeroed at 175-200 yards and be about 10" low at 300 yards. But I wouldn't bet on it until I actually shot it at longer ranges. This is assuming your rifle actually gets the advertised 2820 fps. It wouldn't be unusual for individual rifles to be 100-200 fps slower which would change the trajectory. Also a tiny error at 60 yards may not show up until you get to 200-300 yards.

Using computer sites to plug in numbers is great for figuring hold overs close enough to get you on paper at longer ranges,but they aren't perfect.

 

[Bart B.]

I’ve found Sierra’ Infinity software to be very accurate. Using chronograph data and atmospheric conditions then and later on the range, I’ve got calculated data within 2/10ths MOA in firing at ranges compared to calculated data. From 100 to 1000 yards.

Here’s Sierra’s data for you load. Used 2780 fps as the muzzle velocity as Hornady says there ammo has 2820 but that’s from a fixed test barrel. Off the shoulder, a rifle will shoot about 40 fps less; maybe more. Used a 1.6" scope height above bore. Measure yours then let me know and I’ll rerun the data, but it won’t change very much.

Selected bullet : .308 dia. 150 gr. SP InterLock

Range.........Path..........Energy
Yards..........Inches......Ft/Lbs
0................-1.60.........2573.64
20...............-0.55.........2473.94
40............... 0.32.........2377.40
60............... 0.99.........2283.92
80............... 1.45.........2193.40
100............. 1.71.........2105.73
120............. 1.74.........2020.74
140............. 1.55.........1938.42
160............. 1.12.........1858.78
180............. 0.44.........1781.72
190............. 0.00.........1744.14
200............ -0.50.........1707.17
220............ -1.72.........1635.04
240............ -3.21.........1565.28
260............ -5.00.........1497.86
280............ -7.10.........1432.75
300............ -9.53.........1369.90

 

[murf]

jbmballistics.com

murf

p.s. using a 1.5 inch sight height, your one inch high @60 yards gives a 190 yard zero.

 

[Double Naught Spy]

p.s. using a 1.5 inch sight height, your one inch high @60 yards gives a 190 yard zero.

And about a 30 yard zero. You get two zeroes with every shot.

 

[murf]

yup! a picture of the line-of-sight/bullet travel looks like a suspension bridge. the lines cross at two points. the calculator i used also shows the first crossing @ 30 yards.

murf

 

[gpurp]

Thanks for the responses guys. 190yds is close and I'll call it good enough.

Sent from my SM-G925V using Tapatalk

 

[readyeddy]

Just in case you're interested in your maximum point blank range (MPBR), no more than 3 inches high or 3 inches low from point of aim.

With Hornady 150 grain SP, BC 0.338 G1, muzzle velocity 2820, sight height 1.5 inches, 6 inch target, your MPBR is 269 yards, near zero 24 yards, far zero 230 yards, 2.72 inches high at 100 yards, and 1.6 inches high at 60 yards.