POA How much is too much

[Sierra Hunter]

Been working on my shooting, ten shots groups, true 0 and all the things that come with the off season. Where I get to shoot, my target is often 4-8 ft in elevation above from my rifle due to the field undulations. From those more experienced and savvy, I’m curious if this affects my 0 in the grand scheme of things ?

 

[Koda_]

I don't think even 8ft at 100yds will affect things but I also don't know what the practical limit is... my guess is if your not having to adjust your normal flat shooting position then your fine.

I have zeroed rifles in the woods in slightly uneven terrain that made no difference later on at the gun club. If your zeroing your scope just make sure the true horizontal distance is exactly the same as you want to zero at.

 

[Sierra Hunter]

I don't think even 8ft at 100yds will affect things but I also don't know what the practical limit is... my guess is if your not having to adjust your normal flat shooting position then your fine.

I have zeroed rifles in the woods in slightly uneven terrain that made no difference later on at the gun club. If your zeroing your scope just make sure the true horizontal distance is exactly the same as you want to zero at.

Can you expand on that last part, would those two things ever be different?
I’d think in a perfect world my point of aim or intended zero is on the same horizontal plane. BUT if conditions don’t allow, does that make a material difference at further distances if I was forced to zero my rifle at a target 4-8ft above my rifle.

 

[Koda_]

Can you expand on that last part, would those two things ever be different?
I’d think in a perfect world my point of aim or intended zero is on the same horizontal plane. BUT if conditions don’t allow, does that make a material difference at further distances if I was forced to zero my rifle at a target 4-8ft above my rifle.

If your using a modern laser rangefinder that calculates angle for you then it will never be an issue.

Again, I dont know what the practical angle limit is but if your target is not on the same horizontal plane as the rifle then the straight line distance (hypotenuse) to the target will be different (longer) than the true horizontal (adjacent) distance. Measure your zero distance with the true horizontal distance.


A=100yds, O = 8ft tall = H is 100.04yds actual distance.... not going to make a practical difference shooting a mere 8ft uphill at 100yds zero distance.

 

[Macintosh]

The answer is sort of.

Yes, its an angle that changes the horizontal distance, so it does affect your zero. BUT 6-8’ over 300’ (100 yards) isnt enough that most people could possibly notice it. I think most laser rangefinders arent even accurate enough to measure that difference consistently.

At some point angle definitely needs to be taken into account, so yes it DOES make a practical difference at shooting ranges, obviously a bigger difference the steeper the angle and the longer the range. At that point you need horizontal distance for elevation, but you also need line of sight distance for windage. Ideally your RF will provide both line of sight and angle-compensated values, but I know many only provide one value, in which case youre at a real disadvantage imo.

There’s probably a practical rule of thumb about what points (angle and/or range) it needs to be taken into account. Its not something Ive had to deal with much so Im not the guy to provide that.

You might just plug numbers into a ballistic calculator for a couple distances at 5 or 10-degree increments and see what the results are. That’ll tell you how much error it would cause, and allow you to come up with your own distance/angle “triggers”. For my 6.5cm it takes 15 degrees incline to change my hold .1mil at 400 yards, and it goes up from there.

I think I recall one of the THLR videos going over this. Maybe search for that, or perhaps he can weigh in here, Ive found his practical advice to be helpful in the past. @THLR

This one might help

 

[8nbait]

I just checked this on strelok for you and I needed to go up/down 30° before my zero changed .1mil, 27° for .25 MOA, so at your 2° angle there will be no effect. That was a 6.5 creed with a 143 at 2700 ft/sec.

 

[eaglemountainman]

Simple answer....no

 

[Macintosh]

I just checked this on strelok for you and I needed to go up/down 30° before my zero changed .1mil, 27° for .25 MOA, so at your 2° angle there will be no effect. That was a 6.5 creed with a 143 at 2700 ft/sec.

Exactly…and at 100 yards that .1mil is less than the mechanical precision of most hunting rifles, ie in all likelihood you wont even be able to measure that difference without a large # of shots. Its only at longer range where this matters.

 

[Sierra Hunter]

Thank you gents. Slide comes through again.

 

[dieselchessy]

Here is a link to a cosine table.

https://www.grc.nasa.gov/www/k-12/air