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Bullet weight vs velocity

 
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  #8  
Old 10-30-2013, 12:17 PM
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Re: Bullet weight vs velocity

I think everyone is slightly missing the objective. I'm wondering if the slower heavier bullet will drift more or less than a lighter bullet going faster, ie time of flight. At what point is accuracy (in wind) hindered by low velocity and increased surface area?

Hunting/ terminal performance is 100% irrelevant here.
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  #9  
Old 10-30-2013, 12:33 PM
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Location: South of Canada and North of Wyoming
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Re: Bullet weight vs velocity

Quote:
Originally Posted by ohiohunter View Post
I think everyone is slightly missing the objective. I'm wondering if the slower heavier bullet will drift more or less than a lighter bullet going faster, ie time of flight. At what point is accuracy (in wind) hindered by low velocity and increased surface area?

Hunting/ terminal performance is 100% irrelevant here.
No, not missing the point at all. That's what ballistic calculator's are for. If you go back and read my post I said run the numbers and see which bucks the wind best.

A heavy high BC bullet will almost always buck wind better, at all ranges, than a lighter lower BC bullet.

There are two things and two things only that affect wind drift. They are velocity and BC. However, you almost always have to give up one for the other because to get more BC, you need more SD (weight) and to get more velocity you have to give up weight. In the final analysis, BC almost always trumps velocity.
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  #10  
Old 10-30-2013, 12:34 PM
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Re: Bullet weight vs velocity

6.5 specs vs a 308 @1000 yards, 5 mph full value wind.

140 vld at 2980 2.4 MOA
160 vld at 2700 2.4 MOA

180 nosler accubond at 2700 3.5 MOA
165 nosler BT. at 2800 3.5MOA


BC has more to do with it than anything.

Two examples take the 180 AB and make it .600 BC vs .507 with same speed and drift is 2.8. Take the .507 BC but add 200 fps and the drift is 3.1.

To further my view point the BC difference on the 6.5 bullets is .617 vs .680. The 308 bullets have similar issues in that the heavier bullet has a higher BC rating.

Shoot the highest BC you can at the fastest rate. This is why guys love the wildcat 338's etc for extreme LR.
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  #11  
Old 10-30-2013, 01:38 PM
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Join Date: Oct 2012
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Re: Bullet weight vs velocity

Montana, statement was towards the post referencing hunting.

I don't have enough of my own data to punch actual numbers into a calc but I know there are plenty of people here that do. I understand the theory and speculation, but I'd like to hear about someone w/ actual velocities from different weighted (bc) bullets then the calc can do the rest.

Def appreciate the input.
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  #12  
Old 10-30-2013, 02:42 PM
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Re: Bullet weight vs velocity

Quote:
Originally Posted by ohiohunter View Post
Montana, statement was towards the post referencing hunting.

I don't have enough of my own data to punch actual numbers into a calc but I know there are plenty of people here that do. I understand the theory and speculation, but I'd like to hear about someone w/ actual velocities from different weighted (bc) bullets then the calc can do the rest.

Def appreciate the input.
I have run hundreds of ballistic comparisons and the heavy high BC bullet always does best in the wind. That said, the difference is usually small for low drag (VLD) bullets. I have used my own data and data that I have dug up by searching the internet. In my own experiences I have found 10 gr of weight = 100 fps of velocity in the .308 cal and 5 gr of weight = 100 fps in the 25 cal.

So if you are shooting the 215 hybrid in the 300 WM @ 3000 fps then you can expect to push the 185's at about 3300 fps

When running those velocities and the corresponding BC's you get this @ 1000 yds and 10 mph wind...

215's, 52" drift
185's, 58.7" drift


This is always the result when comparing apples to apples. The heavier, slower bullet with same basic form factor always does better.
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  #13  
Old 10-30-2013, 03:41 PM
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Re: Bullet weight vs velocity

Perfect. Thank you.
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