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7mm-08 vs. .338 Federal

 
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  #22  
Old 04-18-2010, 06:25 AM
Miller Outdoors
 
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Re: 7mm-08 vs. .338 Federal

A caliber that comes to mind that would fit your situation very well is .35 Whelen.
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  #23  
Old 08-28-2010, 12:35 PM
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Re: 7mm-08 vs. .338 Federal

I'd go with the .338 Federal. Here's why: yes they 7mm-08 and the .338 F have about the same powder capacity but guess what? The .338 burns more of it's powder in the barrel. Think of it this way, longer barrels burn more powder right, is it a function of length or volume of the tube? I say volume, and the .338 F with a barrel of equal length as a 7mm-08 has more volume in the barrel, it is therefore more efficient. When I first read the ballistics of the .338 F I was sceptical, then I ran one over my chrono. Holy Crap, I had to think long and hard about how such a small case could push a 200gr bullet at just under 2700 fps from a 22 inch barrel. The only thing that could explain it was the volume of the bore relating to the burn efficiency of the powder. Let me sum this up for you, both cartridges can go 2700 fps; the .338 Federal does it with 200grs while the 7mm-08 does it with difficulty with a 160 gr bullet.

Last edited by garys43077; 08-28-2010 at 12:39 PM.
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  #24  
Old 08-28-2010, 02:05 PM
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Re: 7mm-08 vs. .338 Federal

Quote:
Originally Posted by garys43077 View Post
I'd go with the .338 Federal. Here's why: yes they 7mm-08 and the .338 F have about the same powder capacity but guess what? The .338 burns more of it's powder in the barrel. Think of it this way, longer barrels burn more powder right, is it a function of length or volume of the tube? I say volume, and the .338 F with a barrel of equal length as a 7mm-08 has more volume in the barrel, it is therefore more efficient. When I first read the ballistics of the .338 F I was sceptical, then I ran one over my chrono. Holy Crap, I had to think long and hard about how such a small case could push a 200gr bullet at just under 2700 fps from a 22 inch barrel. The only thing that could explain it was the volume of the bore relating to the burn efficiency of the powder. Let me sum this up for you, both cartridges can go 2700 fps; the .338 Federal does it with 200grs while the 7mm-08 does it with difficulty with a 160 gr bullet.
I don't know about volume, but the area on the back of the bullet is considerably larger which means that the same pressure will create proportionally more push on the bullet.

Fitch
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  #25  
Old 08-28-2010, 04:09 PM
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Re: 7mm-08 vs. .338 Federal

Quote:
Originally Posted by Fitch View Post
I don't know about volume, but the area on the back of the bullet is considerably larger which means that the same pressure will create proportionally more push on the bullet.

Fitch
And more push means what?
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  #26  
Old 08-28-2010, 05:14 PM
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Re: 7mm-08 vs. .338 Federal

If you are not burning all the powder in the barrel you are using the wrong powder.
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  #27  
Old 08-28-2010, 09:52 PM
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Re: 7mm-08 vs. .338 Federal

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Originally Posted by topbrass View Post
And more push means what?
More push equals more acceleration. Simplifying a complex situation for discussion purposes, the basic equation for acceleration F = ma rearranged gives a = F/m which says more force on the back of the bullet gives more acceleration. It also says that smaller mass will accelerate faster for the same force. F = net force on object being accelerated, m = mass of object being acted on by the force, a = acceleration (all in some consistent system of units). In the case of the bullet there are a number of forces - the one that accelerates the bullet at any given moment is the pressure in the bore (pounds per square inch) acting on the cross sectional area of the bullet (square inches). More area means more force all other things being equal.

Fitch
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  #28  
Old 08-28-2010, 10:36 PM
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Re: 7mm-08 vs. .338 Federal

I thought that a larger area would require more pressure to get equal acceleration.
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