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6.5 Creedmoor seems to fast?

 
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  #1  
Old 07-05-2013, 03:43 PM
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6.5 Creedmoor seems to fast?

Guys I finally got some good conditions and went to the range to true up the drop chart. I am using shooter on my iphone and a Kestral to input my data. The chrono gives me 2975fps from 43.5gr of H4350 and a 140VLD. I input my station pressure at 23.4 with a temp in the low 80's. I dial in .2 mills for spin drift and .2 more for the wind. First round at 1009 yards is about 3/4 mill high but dead center for wind. I dial down and plant the second one dead ceater on the plate. Four more and we head up to check the group. A very nice 5in group with almost no vertical. I input into shooter what I dialed to get the group and it spits out my velocity is 3070fps. I say out loud that that cant be. We then hang steel at 500, 700, 900, and repaint the 1230 yard target. I start shooting using the new data and it is spot on all the way out with a 8in group on the 1230 target. Our range sits at 6500ft but I only input station pressure into shooter since the kestrel gives me the true pressure. The rifle has a 28in Bartlein on it but this seems to fast to me. Any thoughts
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Old 07-05-2013, 03:54 PM
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Re: 6.5 Creedmoor seems to fast?

First thing that sticks out is what drag model are you using and what BC are you inputting. Though If you input info incorrectly the error would compound and I doubt you would remain dead on at varying ranges.
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Old 07-05-2013, 04:38 PM
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Re: 6.5 Creedmoor seems to fast?

I use the litz G7 BC that in the bullet library on the Shooter program. Ive double checked all my inputs and my 100 yard zero is a tiny bughole so I know Im not off there. Cant figure this out. Is it possible the barrel is that fast?
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Old 07-05-2013, 04:38 PM
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Re: 6.5 Creedmoor seems to fast?

Did you read the owners manual thoroughly ? I have one on the way, so have not handled it yet and they have a section on calibrating the elevation to barometric pressure if you change elevation.

From the 4500 manual:
"Barometric Pressure and Altitude Adjustment
The Kestrel Meter measures “station” pressure—the actual air pressure in the measurement location— and uses this value to calculate barometric pressure and altitude. Station pressure changes in response to two things—changes in altitude and changes in the atmosphere. Because the Kestrel Meter is constantly changing location and altitude, it is important to enter adjustments or “references” when accurate pressure and altitude readings are needed.

Barometric pressure is station pressure corrected to sea level. In order to make the correction, the Kestrel Meter needs an accurate reference altitude. Altitude is the height above sea level. In order to correctly calculate altitude, the unit needs an accurate barometric pressure reference, also known as an “altimeter setting”. Fortunately, you only need to know ONE of these values (current barometric pressure or current altitude) in order to set your Kestrel Meter up to show accurate readings. "

It then goes on to describe the procedure to make the adjustment.

Altitude reduces drag, so if it thought your altitude/barometric pressure was wrong, it may increase the MV to compensate.

Just check to be sure that part is calibrated properly. I didn't think this kind of calibration was needed but apparently it is.
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Old 07-05-2013, 04:43 PM
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Re: 6.5 Creedmoor seems to fast?

Quote:
Originally Posted by westcliffe01 View Post
Did you read the owners manual thoroughly ? I have one on the way, so have not handled it yet and they have a section on calibrating the elevation to barometric pressure if you change elevation.

From the 4500 manual:
"Barometric Pressure and Altitude Adjustment
The Kestrel Meter measures “station” pressure—the actual air pressure in the measurement location— and uses this value to calculate barometric pressure and altitude. Station pressure changes in response to two things—changes in altitude and changes in the atmosphere. Because the Kestrel Meter is constantly changing location and altitude, it is important to enter adjustments or “references” when accurate pressure and altitude readings are needed.

Barometric pressure is station pressure corrected to sea level. In order to make the correction, the Kestrel Meter needs an accurate reference altitude. Altitude is the height above sea level. In order to correctly calculate altitude, the unit needs an accurate barometric pressure reference, also known as an “altimeter setting”. Fortunately, you only need to know ONE of these values (current barometric pressure or current altitude) in order to set your Kestrel Meter up to show accurate readings. "

It then goes on to describe the procedure to make the adjustment.

Altitude reduces drag, so if it thought your altitude/barometric pressure was wrong, it may increase the MV to compensate.

Just check to be sure that part is calibrated properly. I didn't think this kind of calibration was needed but apparently it is.
Good Point. I have a yellow Kestral I got used off ebay a while back. It needs a new battery and also calibrated.
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"Let glorious acts more glorious acts inspire,
And catch from breast to breast the noble fire!
On valour's side the odds of combat lie,
The brave live glorious, or lamented die;" - Iliad, Book V
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  #6  
Old 07-05-2013, 04:44 PM
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Re: 6.5 Creedmoor seems to fast?

BCG this is a little off topic,but I am curious how do you input your dial up to get your velocity? I have shooter on iphone also but that is the one thing that always bugged me about it I can't get velocity validation that or I'm not smart enough to figure it out. Thanks for any info you can provide.
Rick
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  #7  
Old 07-05-2013, 05:20 PM
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Re: 6.5 Creedmoor seems to fast?

You have to set your reference Alt at 0 in the kestrel to get a corrected pressure mine is good to go. Theses tools have always worked for me with my other rifles. I guess what I am saying is this is not my first rodeo. I just cant see that speed from a Creedmoor. Your Iphone has velocity calibration within the shooter program and you can get to it from the drop table page. It brings up a separate menu were you put in your distance and the drop used to obtain hits and recalculates your muzzle velocity to match your drops.I have the kestrel 2500 nv
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