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G7/Shooter/Exbal conflicts

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  #1  
Unread 08-03-2014, 06:13 PM
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Location: Worland, Wyoming
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G7/Shooter/Exbal conflicts

I have been using exbal on my palm pilot for the last couple of years for my ballistic calculator for my 338 rum. I have used the program to verify my velocity and calculate my drops and it has worked pretty well. So, I moved up in technology and bought a smart phone and down loaded Shooter.

Today I went to the range to get the cob webs off all of my rifles and thought I would refresh my memory with some fresh chronograph readings, so I dusted off my pro-chrono and shot most of my loads through to see if my memory was good. Last year I bought a beta chrono but it seemed to give me faster speeds than the pro chrono and neither seemed to be dead on. So I was using drop charts to verify my velocity. Today the pro chrono was showing 2730 for velocity.

This brings me up to my shooting today. 338 rum ,300 grain berger otm, zeroed at 100 yards, 75 degrees, 20% humidity, 4270 elevation, I entered my go to velocity of 2830 and BC of .818 G1 into my exbal program for my 690 yard target and the solution was 15.25 moa, fired and it was on the money.

Then I went to my phone and entered all the information into Shooter and it told me 13.2

Then I entered the information into G7 ballistic calculator and it told me 13.7

All of the ending velocities are different. What gives?
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Remington model 700 300 RUM LH 26" rem ss/blued receiver lam stock 215 Berger @3070/180 NAB @3300
Remington model 700 338 RUM LH 26" Bartlein 5C #4 Muscle Brake, blueprinted action, sako extractor, jewell trigger, bell and carlson Alaskan stock
Savage LH 22-250
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  •   #2  
    Unread 08-03-2014, 06:46 PM
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    Re: G7/Shooter/Exbal conflicts

    They should not be anywhere close to that far apart at only 690 yards. My best guess is conflicting data entry. I would go over it all again and see what entry is misunderstood or wrong entry. Watch close on shooter for that powder temp / velocity area. I would zero it out for now.

    Also look close at zero entry data.

    Jeff
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      #3  
    Unread 08-03-2014, 07:32 PM
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    Re: G7/Shooter/Exbal conflicts

    Jeff,

    Thanks for replying. I went over all the data inputs very carefully and made sure the zero inputs are all the same. I turned off the powder temp on the shooter app also. When the shooter app wasn't jiving, I went to the G7 program and inputted the data again. None of them are matching. I have used my exbal out to 1250 yards with good hits, but I was thinking it might be nice to use the shooter app on my phone since it has a built in angle meter. What really doesn't make sense is that each of the three programs comes up with a different velocity when all the other inputs are the same. Almost like the BC is changed. Now I am really questioning what my actual velocity is.

    I just inputted the information for my 300 rum with the 215 berger that I tested today at 690 yards. 3100 velocity, exbal gives 11.75 moa with a 100 yard zero, G7 gives 11.8, all of the other information is the same as the 338rum. ?????? 11.75 was right on the money on paper.
    __________________
    Remington model 700 300 RUM LH 26" rem ss/blued receiver lam stock 215 Berger @3070/180 NAB @3300
    Remington model 700 338 RUM LH 26" Bartlein 5C #4 Muscle Brake, blueprinted action, sako extractor, jewell trigger, bell and carlson Alaskan stock
    Savage LH 22-250
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      #4  
    Unread 08-03-2014, 07:39 PM
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    Re: G7/Shooter/Exbal conflicts

    What was your Baro pressure?
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      #5  
    Unread 08-03-2014, 07:46 PM
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    Join Date: Mar 2008
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    Re: G7/Shooter/Exbal conflicts

    Exbal used to be our primary program, and then when we starting using shooter we input all of our data for several rifles and checked the two programs against each other. With no incline or decline they were always nearly identical. Never off by even 1/4 moa. I can't give you an idea of what is off by I am fairly confident that something in your input data has to be off. I know that can be frustrating and I wish you good luck in Figuring it out.
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      #6  
    Unread 08-03-2014, 07:58 PM
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    Join Date: Feb 2007
    Location: Townsend, Montana.
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    Re: G7/Shooter/Exbal conflicts

    Yes Sir. I would keep looking. They should be real close just like they are for your 300 with 215's.

    Jeff
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      #7  
    Unread 08-03-2014, 08:18 PM
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    Join Date: Jun 2004
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    Re: G7/Shooter/Exbal conflicts

    It is acting like the different programs are calculating the bc differently, because both shooter and G7 are giving higher end velocity by about 100+ fps. These are just mathematical equations, but even shooter isn't matching G7 and neither are close to the exbal. I even tried adjusting the velocity down to 2730 and entered it into the G7 and the drop still isn't close.

    With the exact same inputs including 29.8 baro, ending velocity with G7 is 2112 and 2075 with exbal and 2207 with shooter all starting with 2830 as starting velocity, .818 bc g1, 4270 elevation, 75 degrees ambient temp, 20% humidity, 100 yard zero, 0 at zero, 0 incline, exbal shows up 15.25 moa, G7 shows up 13.9, shooter shows up 13.2
    __________________
    Remington model 700 300 RUM LH 26" rem ss/blued receiver lam stock 215 Berger @3070/180 NAB @3300
    Remington model 700 338 RUM LH 26" Bartlein 5C #4 Muscle Brake, blueprinted action, sako extractor, jewell trigger, bell and carlson Alaskan stock
    Savage LH 22-250
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