Scope dope done not match??

[tom338]

So I know my speed, my BC. and my yardage. I put in all the correct specs, altitude, humidity, pressure and scope height. Yet still when I dial it's not correct. What am I missing?? Live at 1250 and need to make a dope sheet for altitude but don't feel very confident in doing so when things are not matching up. And it's not just with one specific scope and rifle. It's with 4 different rifles... So it's not the scope. I must be missing something. I have been using Spot on by Nikon. Yet check with another app and they say the same.

 

[Scottf270]

Just to try something, Hornady website has a couple different ballistic calculators. One is simple and one asks for way more data points. Run your info and see what you get.

 

[Pickettpuncher]

Something is off in your data, or your scopes aren’t tracking as they should.

 

[tom338]

So sat down and did a hard look at data. Thinking my altitude was off a bit and my humidity. Did some comparison with past data and found a couple mistakes. So did 4 charts tonight but will double check data in the morning. How does one get a parametric pressure for someplace you don't live? ballistic app asked to set it for altitude but wow it really changes stuff.

 

[35WhelenAI]

Getting a barometric pressure for anyplace and using it as a set value seems like you're better off just going with the elevation for the area you're gonna hunt. Barometric pressure can change and not be the same when you get to an area. For example, low pressure fronts move through higher elevation in Colorado and effectively make the elevation higher. I think I have that right?

 

[A382DWDZQ]

Is your BC from the bullet manufacturer, or did you calculate it yourself? Sometimes published BC is not quite accurate.

 

[tom338]

BC from the manufacturer, Barnes TTSX 150 grain .284 did

 

[Marshfly]

You get pressure from the nearest airport. Just google it or let the shooter app pull it for you. Get altitude from Onx. Get temperature from your truck or a handheld thermometer in the shade.
Or use a Kestrel and have it spit out DA and temp.
Then you know all of that is true. Then you FIND your actual dope and adjust the MV in the app so the chart matches your real findings.

You true the chart to what the bullet actually does. Expecting the ballistic app to be perfect without adjustments to bullet velocity is simply not the way it happens.

And yes, pressure, temp, and dew point all have an effect at longer ranges. At 6k it is really easy to see a range of Density Altitudes from 12k down to 5k or lessdepending on the weather.

 

[amassi]

BC from the manufacturer, Barnes TTSX 150 grain .284 did

Applied ballistics has the g7 bc @.22
What value are you using?


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[madcalfe]

and what kind of of chronograph are you using?
have you tried to true your velocity?

 

[tom338]

Labradar crony. BC of G1 .45

 

[amassi]

Labradar crony. BC of G1 .45

Try g7 of .22 or G1 of .43


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