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Best powder for short barreled 308

 
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  #8  
Old 04-18-2013, 08:18 PM
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Re: Best powder for short barreled 308

"I disagree with the statement about a powder will produce top velocity in a long barrel as it will a short barrel. If that were the case there'd be no point to having different burn rates for powders."

"Disagree" as you like, it's still a fact. Chamber pressure peaks when a bullet gets about 3 inches from the chamber and it falls quite fast after that because the combustion space is rapidly expanding. The most efficient bore time:pressure curve is the same no matter when the bullet exits; use a faster powder and pressure both rises and falls faster and the average pressure is also less. Speed is higher with a longer barrel only because the bullets continue to accelerate full bore length so the highest average pressure makes bullets fly faster in any barrel length.

Powders have different burn rates because of different capacity and different shaped cases driving different bullet weights down different diameter bores, not to accommidate different barrel lengths. And, it's not uncommon for the highest velocity/pressure curve to not produce the best/most accurate barrel harmonics but that's a different issue.
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  #9  
Old 04-18-2013, 08:34 PM
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Re: Best powder for short barreled 308

I'm not saying you are wrong. I just disagree. Ill consult my ballistics books and actually test it for myself with various different powders. And like I said accuracy isn't my main concern as 100 yards would be a very long shot in a laurentian forest cover of northern Wisconsin. My 45 grains of varget with a 168 will be my control group. I'll test different powders and projectiles to see what will give me what I'm looking for. I was just curious if anyone has any actual data. So far no one has given me real world tested velocities out of a 16.5 barrel.
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  #10  
Old 04-19-2013, 04:41 AM
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Re: Best powder for short barreled 308

Quote:
Originally Posted by aramarine6 View Post
I'm not saying you are wrong. I just disagree. Ill consult my ballistics books and actually test it for myself with various different powders. And like I said accuracy isn't my main concern as 100 yards would be a very long shot in a laurentian forest cover of northern Wisconsin. My 45 grains of varget with a 168 will be my control group. I'll test different powders and projectiles to see what will give me what I'm looking for. I was just curious if anyone has any actual data. So far no one has given me real world tested velocities out of a 16.5 barrel.
Boom tube is correct about the pressure curve. The high presses curve that occurs, which in turn propels your bullet downrange, occurs during the first 4-6 inches of the barrel. The remaining " bleed off" pressure is what continues the push, aided my more barrel length.
With a shorter barrel, however, faster burning powders do pick up some of the velocity loss, if a slower powder is otherwise used.
My recommendation, would be, XBR8208, H322, or H335, or 3031.
I agree with Boomtube . You would need to see a peak pressure curve chart from a pressure Gage equipped rifle. It's amazing what goes on in that milli second in time, and PSI spike. Interesting Stuff!
PS, another variable on the burn rate of choice, is your twist rate.
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  #11  
Old 04-19-2013, 07:07 AM
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Re: Best powder for short barreled 308

My FN TSR 20" likes H 380 with the Hornady 168 A MAX FWIW
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  #12  
Old 04-19-2013, 07:28 AM
Edd Edd is offline
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Re: Best powder for short barreled 308

Quote:
Originally Posted by aramarine6 View Post
Ill consult my ballistics books and actually test it for myself with various different powders.
There is no reason to do that, it's already been done.
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  #13  
Old 04-19-2013, 08:12 AM
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Re: Best powder for short barreled 308

If you are only going to be shooting 100 yards or less it does not matter what powder you are going to use. A deer is not going to know the difference if it got struck with a 165 gr bullet going 3000 fps or 2000 fps if you put that bullet where it is supposed to go because it will be dead shortly.
From years of shooting a 308 I have found that with it's case size you really don't loose all that much velocity when you shorten the barrel a lot compared to larger cases. I use IMR 4895 for all my 308 loading for the simple reason that I came into a boat load of it from pulled down military ammo YEARS ago FREE.
By the way if you want a real deer dropper load try this.
46 grs IMR 4895 with a 125 Nosler ballistic tip. BANG FLOP.
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  #14  
Old 04-19-2013, 09:08 AM
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Re: Best powder for short barreled 308

[
By the way if you want a real deer dropper load try this.
46 grs IMR 4895 with a 125 Nosler ballistic tip. BANG FLOP. [/QUOTE]

I'll have to give this a try.
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