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

[Ingwe]

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?

 

[coop2564]

Its hard to know...but airlines are brutal with luggage. There is a reason guides like for customers to check scopes on arrival, this is common.

 

[SilverbulletMAG]

Could be as simple as indoors vs outdoors. Humidity and temperature difference (depending on powder used and sensitivity) along with wind and drizzle....seems logical to have slight difference.

 

[Ingwe]

Its hard to know...but airlines are brutal with luggage. There is a reason guides like for customers to check scopes on arrival, this is common.

I drove out here with the gun in the back of an SUV...padded, hard, Pelican case

Could be as simple as indoors vs outdoors. Humidity and temperature difference (depending on powder used and sensitivity) along with wind and drizzle....seems logical to have slight difference.

I'm using RL23 powder which is supposed to be very stable.
I'm sure that the environmental changes mean something but I didn't think it would at only 100yards

 

[aushunter1]

Could be as simple as indoors vs outdoors. Humidity and temperature difference (depending on powder used and sensitivity) along with wind and drizzle....seems logical to have slight difference.

Altitude & temperate would definitely has an affect of POI.
Temperature wise your rifle is going to be affected a bit as well, heard of 'cold bore' shot? Also even though minutely on you what happens to metal when its heated-it expands, what happens when its chilled-in contracts.
Altitude-higher you go the air is thinner & barometric pressure influences the density of the air.

I always re zero when I travel from sea level to the mountains OR allow for the affects knowing it is going o be slightly different.

 

[SilverbulletMAG]

Altitude & temperate would definitely has an affect of POI.

Not sure why you quoted me but I don't disagree. Although, 2K elevation change will have negligible difference at 100 yards.
For reference, using a generic 30-06 load with 180 accubond plugged into a ballistic calculator comes up with an impact difference at 100 yards of .0008", 7fps faster velocity, and 1ms quicker flight difference (vs at sea level).

 

[Ingwe]

Not sure why you quoted me but I don't disagree. Although, 2K elevation change will have negligible difference at 100 yards.
For reference, using a generic 30-06 load with 180 accubond plugged into a ballistic calculator comes up with an impact difference at 100 yards of .0008", 7fps faster velocity, and 1ms quicker flight difference (vs at sea level).

So what do you think is causing my poi shift? Or I should say, are the difference between conditions I described enough to make the shift that I described?

PS I thank all of you guys for your input

 

[aushunter1]

Not sure why you quoted me .

Because your reasoning made sense.

OP, I think its a combination of what I outlined & SBM hit the nail on the head with the ballistic calculator input.

If you have a look at those programs they want to know as much detail as possible.
Eg If you put in 0 elevation & your data you will grt xyz moa, if you put in 2100ft & ypur data it will give you a different moa, in other words it all has an affect.

 

[Rick Richard]

Is your shooting technique and rest the same? Shooting from a different platform (bag, bipod, etc) will make a difference along with change in head and shoulder position. Just saying.

 

[SilverbulletMAG]

So what do you think is causing my poi shift?

Pure speculation on my part but beyond what I initially listed (all atmospheric differences -i.e. wind and rain changing POI), it could also be the way you were shooting? Were you shooting off a bipod and rear bag in one instance and using a rest/leadsled in another instance? Different cheek weld? Parallax? Shooting indoors in a t-shirt and shorts but layered up with bulking clothing in KS? Just spitballin'...lol

 

[Ingwe]

Yes fellas you are correct and I didn't think of that.

In Kansas I am shooting off of a wooden bench with a ft rest and rear sandbag...when I sighted the rifle in in NY, I shot off a a wooden bench rest but with sandbags in rear AND front.

PS: my scope is a Swarovski X5 6-18 and I bought a calibrated turret knob for it. I very carefully gave Swarovski my inputs. I know found that it is dead-on at 100-500 yards.
After 500 yards, the next plate is a 1,000, and when i dial my knob to 1,000 it is impacting at least 2 feet low.

I often heard that the calibration of these ballistic knobs are only accurate to 600 or so yards, and that seems to be true in my case

 

[Elkeater]

My rifle which prints .5 MOA or less (shot a 2 inch group at 610 yards a couple days ago off the bipod) shifts POI about 3 inches at 200 yards depending on if I'm shooting off my Caldwell tack driver bag or a bipod. So my guess would be the rest change as well.

 

[Muddyboots]

Actually you are probably not far off being concerned coming from NY to KS. That is more of a planetary shift and the rotation of bullets are in reverse in NY.....

OK, couldn't resist as a former NY'er and glad to be a former NY'er.

 

[User4302021]

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?

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.