Bretheren,
Until I get all set up for casting 500+ gr bullets, I'm getting started on dialing in on the many MANY hundreds of .458, 405gr flat nose bullets. I've started a spreadsheet to make MOA notes on distances with them.
Now, I know these bullets have the trajectory of a brick. However, if I know the velocity, weight and BC, I can probably make some educated notes. But I cannot find any definitive BCs on this kind of bullet.
The best I've come up with is .303, but that sounds WAY to generous...especially when I see the numbers it produces in my calculator.
Can anyone share if they know what the ball-park BC of these kinds of bullets is?
BC of a 405gr FN
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ccongos@me.com
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BC of a 405gr FN
-Chad
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JonnyV
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Re: BC of a 405gr FN
.303 probably isn't that far off...If you have a LabRadar chronograph, you can get readings at the muzzle and then downrange as well. Having two sets of velocity readings means you can calculate your BC using one of the many ballistics calculators available. Take those readings and your BC number, plug it into a Kestrel and you're off to the races.
PS, don't be bringing a Kestrel to the firing line of any competitions. Folks don't like that.
PS, don't be bringing a Kestrel to the firing line of any competitions. Folks don't like that.
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Castaway
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Re: BC of a 405gr FN
The Lee 405 RNFP has a listed BC of 0.225
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bobw
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MikeT
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Re: BC of a 405gr FN
I may be confused about this, but I think BC is velocity dependent.
If you have a MV measurement, and several elevation settings for various yardages, you can play with a ballistic calculator and by changing the BC number, you can get the estimated trajectory to match your actual sight settings for those yardages. This would be your approximate average BC.
I did this many years ago to calculate my 800, 900, & 1K elevations, when I only had sight setting out to 620 yards. They were accurate enough to be within 1-2 minutes of the actual sight settings.
Keep on hav'n fun!
MikeT
If you have a MV measurement, and several elevation settings for various yardages, you can play with a ballistic calculator and by changing the BC number, you can get the estimated trajectory to match your actual sight settings for those yardages. This would be your approximate average BC.
I did this many years ago to calculate my 800, 900, & 1K elevations, when I only had sight setting out to 620 yards. They were accurate enough to be within 1-2 minutes of the actual sight settings.
Keep on hav'n fun!
MikeT
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ccongos@me.com
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bobw
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Re: BC of a 405gr FN
It works but so does just about any ballistic program. The 25 year old one on excel that I have. mv, sight height. Bc zero at 50 or a 100 just a matter of moa in drop added to sight setting. Bobw
bobw