change in POI with change in elevation

[jaybic]

Hello all,

I am just curious if anyone has any thoughts or insight on this. I sighted in my 243ai dead on at 200 yards here in Rochester MN(1200ft),went out to North Dakota coyote hunting(elevation 2600ft) and promptly shot over a 350 yard coyote that according to my dope from home, should have fallen over dead. Does that difference in elevation make that much difference? The shot seemed very steady and no high wind to speak of. I just ranged him at 354 with my Leica, dialed the MOA that had been proven on a metal coyote target at home and missed high.

Ideas?

Thanks,

Jamie

 

[Dr. Vette]

Jamie,

This is one of the easiest calculators on the 'net to use:

Handloads.Com Ballistic Calculator

Put in all of your correct numbers, and run it at your elevation as well as the hunt elevation. You'll then see for yourself.

Oh, and did you verify the sight in at 200 yards once you arrived in ND?

 

[ZSteinle]

Jamie,

This is one of the easiest calculators on the 'net to use:

Handloads.Com Ballistic Calculator

Put in all of your correct numbers, and run it at your elevation as well as the hunt elevation. You'll then see for yourself.

Oh, and did you verify the sight in at 200 yards once you arrived in ND?

I think he was asking about 200 yard zero point of impact shift. Simple answer yes. but with your difference in elevation change I wouldnt have worried about it. If you were going from 1200 to the mountains say 7 or 8000 I have seen substantial differences.

 

[royinidaho]

I've been told that POI changes 0.10 MOA per 1000' of elevation change.

No distance was associated with this info.

Run the numbers on shooting solution software and see what comes out.

 

[Greyfox]

I have seen this vary with my particular rifles. I always check my zero with a change in hunting locations which range on an annual basis from 500' to 5000' elevations, and temperatures range from 20-80F. I worry more about extreme temperature changes and getting my zero knocked out during transport. Interestingly, my 6.5x284 has rarely required a 200 yard zero change once set at my home location( 350') I definitely have to account for the these changes in my ballistic calculator for my elevation settings. I have had other rifles that occasionally needed to be re-zeroed, but rarely more than a few clicks. I'm not sure this was due to the elevation or temperature.. I would think that it would be difficult to discern differences at 200 yards, particularly with the elevation change you mention.

 

[jaybic]

Thanks for the replies fellas,

No, I did not check the zero once I got out to ND and probably should have. I have a Kestrel NV4500 w/Applied Ballistics and the dope I had written on my stock(gathered at home at 1200 feet elevation using the Kestrel, shot off a sturdy bench and proven on steel targets) was what I went off of so I was just floored when the coyote didn't tip over. I guess I knew elevation could make a difference but I didn't expect it to be very much. Is it reasonable on my next trip to bring a chronograph and a steel target and get some "North Dakota" dope or can the kestrel be made to take elevation changes into account? what is the best way to not have this happen again(I am bearing in mind that it could have simply been shooter error but the conditions and shooting position were about as good as a guy could have asked for and I have shot lots of coyotes so I don't really chalk it up to coyote fever.....I also have the Shooter APP on my phone, Strelok and Sierra infinity v7 if any of those may help....

anyway, thanks again for the insight fellas from a guy that used to believe that any coyote farther than 300 yards was a poke and hope deal.....

Jamie

 

[Greyfox]

I doubt very much that given your zero was on, that the elevation change you mention would be enough to miss a coyote at 350 yards. You can test the variation in elevation/temp at this distance easy enough with your ballistic program. If I have the opportunity, when I check my zero, I will also try to make a test shot on a small rock at the the longest range I intend to shoot game. At the very least, it's a good equipment test, and confidence builder.IMO.