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+--- Thread: Ballistic Apps and the Importance of Accurate Data (/showthread.php?tid=7330)
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Ballistic Apps and the Importance of Accurate Data - waveslayer - 06-25-2014
I use the Shooter App on my phone, I love it. It is as good as your inputted data is. It asks for twist rate, etc.... I also use my Kestrel that has Blue Tooth, no stress if there is no service. I hook my phone up to the Kestrel and it will automatically populate into my App and give me the correct solutions. You can even factor in Corilios Effect. I have noticed that you need to true your App to your load. I go out and shoot at certain yards make notes of my MOA for center hits, no stress on wind, for truing, then I use the Velocity Calculator to correct the App to give me accurate feedback. Now I am testing and also asking, what the actual BC's are for some of my loads because of the difference in velocity I get from my Chrono, Magnetospeed, and Velocity calculator.
for example: my loads run at about 2648 from a 24" barrel with XBR powder and the 123 Amax... but when I went back East to shoot I was shooting very high at 500 and 600 yards, I had to adjust the velocity to 2700.66 (per my velocity calculator on Shooter)... so my BC could be off or the MagnetoSpeed and my Chrono are both way off.... so the mystery continues.
Overall great lessons you learned and I am learning too. I know Brandon Webb says that all he needs is 3 bullets and the velocity for those, then he can shoot well past 1500 yards without having to even check his actual data.... I am not getting the same results.
Get the Kestrel that has bluetooth and hook it up to your App and get your weather readings there. I wish they had a booster to get more then 30' distance on the Kestrel's Bluetooth... then I could place my Kestrel out close to the target to get actual wind and data...
Ballistic Apps and the Importance of Accurate Data - LR1955 - 06-25-2014
waveslayer Wrote:I use the Shooter App on my phone, I love it. It is as good as your inputted data is. It asks for twist rate, etc.... I also use my Kestrel that has Blue Tooth, no stress if there is no service. I hook my phone up to the Kestrel and it will automatically populate into my App and give me the correct solutions. You can even factor in Corilios Effect. I have noticed that you need to true your App to your load. I go out and shoot at certain yards make notes of my MOA for center hits, no stress on wind, for truing, then I use the Velocity Calculator to correct the App to give me accurate feedback. Now I am testing and also asking, what the actual BC's are for some of my loads because of the difference in velocity I get from my Chrono, Magnetospeed, and Velocity calculator.
for example: my loads run at about 2648 from a 24" barrel with XBR powder and the 123 Amax... but when I went back East to shoot I was shooting very high at 500 and 600 yards, I had to adjust the velocity to 2700.66 (per my velocity calculator on Shooter)... so my BC could be off or the MagnetoSpeed and my Chrono are both way off.... so the mystery continues.
Overall great lessons you learned and I am learning too. I know Brandon Webb says that all he needs is 3 bullets and the velocity for those, then he can shoot well past 1500 yards without having to even check his actual data.... I am not getting the same results.
Get the Kestrel that has bluetooth and hook it up to your App and get your weather readings there. I wish they had a booster to get more then 30' distance on the Kestrel's Bluetooth... then I could place my Kestrel out close to the target to get actual wind and data...
WS:
You are illustrating a couple of my points.
First, are you sure either of your shooting locations were really 500 yards? Just a SWAG but my bet is if one was + - about twenty yards from 500, then you probably have your answer. Grendels are not exactly flat shooters so you need to be very good at estimating range but it also depends on your success criteria.
Second (assuming both of your ranges were really 500 yards), fifty FPS equates to about 3/4 minute. Which means at 500 you were about four inches high. Is this significant? Depends on your target size but under most circumstances, it isn't significant. That is less than one minute and unless you are on the level of Stokes and are using loads you know absolutely hold under a minute at 500 with your equipment and you, then those shots could well be going within the capability of your load. rifle, sights, and you.
Third, I would ask you what your call area is and if your shots went within your call area.
Forth, I would ask you if you had a change of elevation between your zero and these shots of over 3000 feet. That is where I start to see differences in zero because of elevation.
Fifth, light conditions and mirage. From Biathlon I will say that you do experience zero changes from dark conditions to very bright and or as the sun passes across the sky. We have a saying to turn into the sun. However, this is more pronounced if the sun is going across your line of sight from left to right or right to left. And more in your eyes. Very low on the horizon, too. How much change? Experience tells you that, intuition perhaps. I am sure someone can make an app that could probably come close.
I take it the Kestrel feeds the azimuth of your rifle barrel plus longitude and latitude into your cell phone? I believe both are needed to compute corilios effect.
And so far I haven't been able to prove that coming a minute right or left automatically at 1K yards due to spin drift has any meaning at all. I have seen a couple rifles where it probably was a factor but most guys can't get a good enough no wind zero at 1K and or can't dope wind well enough (within 1 minute) for me to believe that a shot out the left was due to spin drift.
So there are a couple of things that you can think about if you want. I am sure there are more but those are off the top of my head.
LR55
Ballistic Apps and the Importance of Accurate Data - waveslayer - 06-25-2014
The Ranges were verified with Leica Range Finder, we made sure of that. I got into it with the board president at my range out here in this communists state, he was wrong by 8-22 yards on all his ranges.
2) I would like to think I am on the same level as Stokes
My Grendel is a Tack driver and my loads are all hand loads, that takes more time to load then my wife likes. That's why I have a nice couch now.3) Shots were within 1-2 inches of called shots, I checked my data. I had one flier from me getting excited and jerking the trigger. We were lucky no wind at all!
4) Good question, not sure the elevation was, I will look at my data that's on my data book at home. I bet the elevation was different not sure how much. Erie, PA to Corona, CA (where the range is). I will double check my app and data logs.
5) Sun was at my 8-9 moving to the 2-3 O'Clock position.
I don't use the Coriolis Effect really, don't shoot it far enough yet to have it matter. The nice thing with the Shooter App is you can have it auto populate all the Kestrel data, Humidty, Dens, etc... for you and then you can get the calculations. Cool feature.
As for drift. If I shoot like Strokes then yes the barrel twist is jacking my groups at 1,200. Just Kidding.
Thanks for the heads up, I will look into it. Anyone have the G7 BC for the 120 SMK?