 |  | | | |  | |  |  | .177 vs. .22 Wind Drift Question |  | |  |  | |
 Posted: Sat Mar 17, 2012 7:50 am |
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| Joined: 13 Nov 2011 |
| Posts: 1138 |
| Location: Des Moines, Iowa, USA |
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I have always been under the impression that--all other things being equal--a .22 pellet, being heavier, is less affected by cross wind. I just noticed though on Chairgun the results are just the opposite. What gives? Chairgun has been right on in predicting my pellet drops so far, is it inaccurate in the wind-drift calculations like it seems to be (vastly underestimates penetration in animal tissue, in my opinion/experience) in the predicted penetration calculations?
-Rob |
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It's never too late to have a happy childhood. |
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| Posted: Sat Mar 17, 2012 10:25 am |
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| rsterne |
| Moderator |
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| Joined: 15 Jan 2008 |
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| Location: Coalmont, BC |
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Weight is only part of the answer in wind drift.... The amount of wind drift is proportional to the DIFFERENCE in flight time of a pellet in a vacuum to what it is in the real world.... The major factor is the Ballistics Coefficient, with velocity being the other factor....
The BC is proportional to the Sectional Density divided by a "shape factor".... The SD is the "weight per bore area" and as such is proportional to the caliber for pellets of identical shape.... Therefore, for pellets of identical shape and density, the BC is proportional to the caliber....
If you compare pellets of the same SD and shape, you will find that the BC is, in fact, better for larger calibers.... Just to throw a monkey wrench in the works, however, the BC is NOT a constant and varies with velocity, and not in a linear fashion.... Once over a certain velocity, it tanks.... The BCs in ChairGun seem to be either an average value, or have just been measured with one gun at one velocity as they are only valid as a general guide....
Bob |
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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal: Too many to count! |
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| Posted: Sat Mar 17, 2012 4:10 pm |
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| Silver Status Member |
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| Joined: 13 Nov 2011 |
| Posts: 1138 |
| Location: Des Moines, Iowa, USA |
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I see. Thank you.
I entered in my own BC to be the same for both calibers, and the same velocity, and they did come out the same.
-Rob |
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It's never too late to have a happy childhood. |
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