Point of impact question

[marcbateman]

Topic came up in a discussion today, and I hadn’t really thought about it. If you’re sighting in a rifle at 200 yds close to sea level, will the drop rate be affected at all at 10,000ft?
Thanks for any input

 

[Pickettpuncher]

Absolutely. Air density is much different from sea level to 10k feet.

 

[ndayton]

yes, but depending on the cartridge the drop difference is negligible at 200 yards.
Maybe a half an inch

 

[marcbateman]

yes, but depending on the cartridge the drop difference is negligible at 200 yards.
Maybe a half an inch

308 Nosler 165gr Accubond

 

[Pickettpuncher]

I agree with the negligible difference at 200. Once you start stretching it out it’ll definitely start compounding.

 

[ndayton]

308 Nosler 165gr Accubond

.19" difference based off my ballistics calculator.

 

[marcbateman]

Thanks guys

 

[ChrisAU]

Zero at 100, and then generally you'll be within one adjustment value of zero just about anywhere (I.E, your zero will change, but not enough to cause you to correct for it in your scope). Then, once you've confirmed dope at home, you can just adjust environmental factors in your calculator for anywhere you go without having to re-zero your rifle.

 

[Reburn]

Zero at 100, and then generally you'll be within one adjustment value of zero just about anywhere (I.E, your zero will change, but not enough to cause you to correct for it in your scope). Then, once you've confirmed dope at home, you can just adjust environmental factors in your calculator for anywhere you go without having to re-zero your rifle.

This is on the money.

 

[tak]

Zero at 100, and then generally you'll be within one adjustment value of zero just about anywhere (I.E, your zero will change, but not enough to cause you to correct for it in your scope). Then, once you've confirmed dope at home, you can just adjust environmental factors in your calculator for anywhere you go without having to re-zero your rifle.

agree with this,
I completely understand a 200 yard zero for typical hunting and many hunters. I won't knock that. However, for long range shooting, or if you are going to be dialing, a 100 yard zero is better for several reasons. There are just too many variables at 200.

Also, the gunwerks Revic Ops calculator allows you to calculate "zero angle". I can't fully explain how that works, but basically uses the very small angle between your line of sight and bore instead of the zero. In this case, I think that would even remove any possible change of impact at 100. (I'm not saying you need to worry about that, but just an example of where calculators are heading). You would need to be very exact on zero and school height.


Temperature and Elevation are your two biggest environmental factors. Sometimes they can minimize each other. I'm helping a friend get ready for an elk hunt. (Set him up with a 200 yard zero btw.) We are at ~1000 feet and 90 degrees. His dope is very close at 6000 feet and 60 degrees where he's going. Higher altitude the bullet is flatter, also higher temperature the bullet path is flatter. They often can cancel each other out - higher elevations are usually colder.

 

[Ucsdryder]

Zero at 100, and then generally you'll be within one adjustment value of zero just about anywhere (I.E, your zero will change, but not enough to cause you to correct for it in your scope). Then, once you've confirmed dope at home, you can just adjust environmental factors in your calculator for anywhere you go without having to re-zero your rifle.

Joseph von Benedict says you’re stupid. (Btw I agree with you).

 

[XLR]

agree with this,
I completely understand a 200 yard zero for typical hunting and many hunters. I won't knock that. However, for long range shooting, or if you are going to be dialing, a 100 yard zero is better for several reasons. There are just too many variables at 200.

What makes the most in my head is zero at 100, then dial your scope to 200 if you have external turrets. Normally its about 2-2.5 inches high. What this does is puts you dead on at 50 yds, 2-2.5 inches high at 100, and dead on at 200. But you still have a quality zero so if you want to dial up to shoot at 500 you can!

 

[Laramie]

Topic came up in a discussion today, and I hadn’t really thought about it. If you’re sighting in a rifle at 200 yds close to sea level, will the drop rate be affected at all at 10,000ft?
Thanks for any input

Here is a free to use ballistics calculator- https://www.hornady.com/team-hornady/ballistic-calculators/

I don't dial. I use a Leupold with the B&C reticle. At my home elevation of 1500' I sight in zero at 200. My corresponding reticles are very close at 300, 400, and 500 yards. At 9,000', my main crosshair is close to zero at 240 and the corresponding reticles are very close at 350, 450, and 550.

For most hunting distances, you will remain in the vitals with no adjustment. Past 300, it does start to make a difference though so a person should practice at elevation imo.

 

[tak]

What makes the most in my head is zero at 100, then dial your scope to 200 if you have external turrets. Normally its about 2-2.5 inches high. What this does is puts you dead on at 50 yds, 2-2.5 inches high at 100, and dead on at 200. But you still have a quality zero so if you want to dial up to shoot at 500 you can!

Yessir!
one thing I miss about my vortex razor was that I could dial the turret to 0.4 mils and then lock it there if hunting. I'm sure there are others that do that, but I haven't seen them.

 

[TheGDog]

Nikon has the "Spoton" app out there for free. It's purpose is to let you plug in values about the cartridge and zero and it show you what the lines in their BDC reticles should equate to and where to adjust bullseye to if it is less than the 100 or 200 to your sight-in target.

So if like me, you have to first get a pre-zero at a wimpy indoor range of only 25yds. You can do that first by knowing the amount below the crosshairs you're supposed to hit at 25 in order to be spot on at 100 or 200 or whatever you chose.

But here's the thing... they also allow you to print out a Field Ballistics chart. I keep a screenshot copy in my phone for out in the field. And realistically I only memorize the 100, 200, 300 drops. And vaguely put into my memory the wind drifts on those distances for 10mph sideways wind.

The app similar to this that Vortex has on their site also lets you specifically put in the latitude longitutde of where you'll be shoot at to derive the altitude and thus take air density into account in the calcs it does for you. You then just have to deal with providing air temp values, which it also takes into consideration in the calcs it provides.

So between using those two free apps, if you study the results and look at the ballistics charts they can make for you showing bullet path as sighted, drop per distance, and wind drift. You should totally be able to figure it out in the field, just pull up your phone, look at the info you screenshot... make your best guess on wind and try!

 

[JakeSCH]

Here is a video on zero angle brought up by gdog.

While zero angle is the correct way, like others have said for most hunting distances it should be be in the vitals.