Different State - POI Change....is this normal?

[Ingwe]

That big of a change at 100 wouldn't be caused by altitude or temp. It could easily be the difference in lighting conditions though.

You zero'd indoors where there was likely no light refraction between you and the target. The target was exactly where you saw it.

When you get outside, the sun causes the target image to displace. Your gun hasn't shifted at all, the target just isn't exactly where you think it is.

To test the theory, shoot your gun again in the shade, or early in the morning before the sun is high. If it comes back to zero, you know that was your issue.

There was no sun and it was drizzling in Kansas but I am going to shoot again in NY when I get home

 

[User4302021]

There was no sun and it was drizzling in Kansas but I am going to shoot again in NY when I get home

Well, that's interesting. If it is a positional issue or a equipment issue, the groups usually move up on the vertical not down.

 

[Ingwe]

I am thinking now it is what Rick Richard suggests that it was because of a different rest and hold

 

[elf]

Lot of very good possibilities for you to check. Only other suggestion I have is: Wooden stock? If water gets in the barrel channel, it can surely affect POI. The barrel would have to be bedded tightly for this to occur.

 

[fightthenoise]

I travel from Colorado to Minnesota every year to hunt whitetails. I take two rifles and my dad comes up from Texas with his. All 3 need to be adjusted upon arrival every year. My rifles use RL26, and my dad shoots factory Hornady. The change isn't huge, usually FPS related (elevation), but POI shift is real. I dunno if it's atmosphere or altitude or just getting thrown around by airlines. Probably a combo of all three. My brother flew out last year from VA and didn't test his rifle upon arrival. He missed two deer.

 

[Southernfriedwerewolf]

Your POI shift is likely to be all environmental.
Get this book, there's others too, like Applied Ballistics and read to see why.
https://www.amazon.com/dp/1581600682/?tag=lrhmag19-20
Enjoy

 

[Shootin4fun]

Hello Fellas,


Do you all think that the difference in weather and altitude caused the POI change?
My gun was in a hard Pelican case so I know that it didn't get banged off zero.

What do you all think?

Nope, alt and hum at 100 yards for a 7RM isn't going to make that much of a diff. Very likely the shooting position/support, etc. I have seen a bipod off of concrete vs forend off of a backpack has made that much of diff. Also prone vs standing. Diff amount of resistance against the recoil...huge diff, can be measured by a chrono. So many factors....Much of my range shooting is testing all these diff variables. It's a good excuse to get out to the range. I keep all targets and record all data. Hard to find public long ranges that let you put up paper and retrieve it though which is a big bummer for me. Only about 10% of the time do I do free range metal target shooting. Endless data collection.

 

[DKSDonnie]

Hello Fellas,
I am shooting a 7mm Rem Mag 175gr Accubond Lr at 2,850fps.

I sighted in at a 100yard indoor range at 80 degrees in NY at sea level.

I am now in Kansas at 2,100 ft above sea level, in a light drizzle, with 40 degree temp.

So here in Kansas, I fired a 5 shot group at 100 yards and found that my bullets were sub 1/2 MOA just like they were when I sighted in NY but the group was 1" low and 1/2" left.

Do you all think that the difference in weather and altitude caused the POI change?
My gun was in a hard Pelican case so I know that it didn't get banged off zero.

What do you all think?

In my experience, the change of 2,100' in altitude would not make a noticeable change. I would suspect the 40 deg temp change had more of an effect. I have a 7MM WSM I was reloading and shooting for and shot sub 1/2 groups at 100 yds easily in 40 deg temps. Warmer weather came along and shot it again at right around 80 deg and was in the shade. It shot 2.5" to 3" groups and consistently walked dead left after each shot. I was sure not to cook the casings in the chamber after each shot and let it cool for at least 10 min after each shot but it still went crazy. My fps did rise after each shot through the chrono. Heat brings pressures up which changes fps which changes harmonics and obviously POI. Check your fps in 40 deg temps versus 80 deg temps and I think you'll find your answer.
'

 

[Jeffrey Van Zandt]

Density? altitude always know what it is get a Kestral 5700 with AB

 

[Shootin4fun]

I have sighted in at 75 degrees on a 243, then shot at 30 degrees same scope setting. (100 yards) POI shift doesn't seem to be the cold air, but the freezing barrel.

 

[MAD10]

your POI should not change at 100 yards driving from NY to KS...of course your come ups or windage adj at distance will be different but your ballistics app or kestrel will account for that and give you the correct adjustment based on your current atmospherics.

I would say that "lighting" indoor vs outdoor and your "shooting position" are attributing to your change in POI.

For example if I happen to have my adjustable cheek piece lower than when I zeroed I will in fact hit low at 100 yards. There is a reason I shoot everything from prone and avoid benches, lead sleds vs. what I will use during a comp or hunting. In the military its called "train as you fight" meaning use exactly what you'll use in the field...for me that means a bipod and a rear bag DURING LOAD DEVELOPMENT, SIGHT IN AND PRACTICE.

 

[rugers]

Lots of variables change in alt change in powder temp change in barometer readings could possibly do it but it only happens to me with a much bigger spread of temp like 80 degrees to -20 but I do rezero at hunting temps and its usually not very much. Always a good idea to check and if necessary readjust zero if needed.

 

[Poppadoer]

Enjoy reading everyone's opinion on this subject,very interesting.I have to agree with Dog Rocket on this one.

 

[floyd kittrell]

More than likely it is the difference between your bi-pod and soft rest . It changes my impact that is why I now use a "SLIK" tri-pod , made by a USMC vet . The elevation change in my 2 out west rifles is about 3/4 MOA at 5500 and 1MOA at 7500 ft . I don't re-zero just deduct it from my dial when I elevate for shot or deduct from my reticle MOA . has always worked for me. I also use G-7 range finder , Kestral wind meter and NF ATACR MOA scopes . JMHO but wouldn't place a bet on any of this,short story is , if I was going to hunt with attached bi-pod , I would zero with it in prone position on dirt , not concrete