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Reloading Techniques For Reloading


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powder charge vrs barrel length

 
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  #1  
Old 08-11-2013, 08:57 AM
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powder charge vrs barrel length

It seems most loading data is done in a long barrel like at least 24 inches. So obviously a shorter barrel needs a smaller than posted load or else your buying powder and blowing excess out side the barrel.

So it's logical a 18.5 inch barrel definitely need lighter loads.

Any thoughts on how much lee one should de-rate the book values based on barrel length?
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  #2  
Old 08-11-2013, 09:24 AM
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Re: powder charge vrs barrel length

What about using a faster burning powder?
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  #3  
Old 08-11-2013, 09:40 AM
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Re: powder charge vrs barrel length

in a way you are correct. But, the proper way to choose powder is by expansion ratio. A bit complicated to understand but here is the short version, case capacity + caliber + barrel length (barrel length is the distance from the base of the seated bullet while in the chamber to the muzzle, not the listed length from the manufacture, this is measured useing a dummy round). Once you know your BL, CC and caliber from a chart or slide rule you can determine your burn rate and that is how choose your powder.
If what I have just posted sounds greek to you then use your books and publications, always confirm your load, start with the start load, load 5 then load 5 each of .5 grain incraments untill you get to the max load. go to your range and at 100 yards from the start load fire your 5 shots, (dont worry if the sights are a little off you are interested in groups at this point) take note of the size of the group and signs of preasure. Then do the same for the next incrament and the next ect. untill you notice the tightest group. You then have the most efficiant load combo of that powder and bullet for that rifle.
The books list 150 grain bullet in a 7mm rem mag useing IMR7828 SS, 63.4grn max 68.7 the vel 2851 to 3100fps. In my savage the tightest group is at 67.0 grns chrono at 3010fps so that is where I keep it.
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  #4  
Old 08-11-2013, 09:41 AM
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Re: powder charge vrs barrel length

Ya I realize that principle. However my question is that if the recommended load is 54 gr of 4831 in a 24 inch barrel. An 18.5 inch carbine should discount the data to a lesser load so as not to finish burning the powder out side the muzzle.
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  #5  
Old 08-11-2013, 11:29 AM
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Re: powder charge vrs barrel length

There is no need to lighten your load to compensate for a shorter barrel. Likewise, going with faster powder in a shorter barrel will do nothing for you.

I know it seems counter-intuitive, but the way to maximize performance in a short barrel is to go with heavy for caliber bullets and slow powder. The key to the whole thing is pressure rise time. A heavy bullet will help build pressure sooner by providing more resistance. If you can put together a combination whose optimum burn rate range is in the neighborhood of the 4350 type powders, you can benefit from the steeper pressure rise of powders like RL-17.

The current crop of factory ammo from Hornady in the Superformance line and in chamberings like 6.5 Creedmore, .375 Ruger, and the Ruger Compact Magnums all take advantage of the fast rise time available in some of the newer powder formulations to deliver excellent performance from short barrels.

Unfortunately, the powders they use are not currently availabe to handloaders.

Last edited by benchracer; 08-11-2013 at 11:31 AM. Reason: spelling
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  #6  
Old 08-11-2013, 12:03 PM
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Location: New germany, NS
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Re: powder charge vrs barrel length

if you cannot understand that a load below sugested start is capable of produceing unsafe preasure than you donot understand basic safety.
Read the manuals, never go below start and never go above max. If you choose to ignore this then it is only a matter of time till your favorite rifle, shotgun or handgun goes boom in a very unpleasant way.
And never under any circumstance use any load that you get from here or anywhere else untill you are able confirm it by a differant sourse. And that goes for everybody's load datta, be it Layman, Lee, Speer, Alliant, Hornady, Nosler and any other publication (includeing me!).
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  #7  
Old 08-11-2013, 12:33 PM
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Join Date: Aug 2013
Location: Stockton, Utah
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Re: powder charge vrs barrel length

Quote:
Originally Posted by g0rd0 View Post
in a way you are correct. But, the proper way to choose powder is by expansion ratio. A bit complicated to understand but here is the short version, case capacity + caliber + barrel length (barrel length is the distance from the base of the seated bullet while in the chamber to the muzzle, not the listed length from the manufacture, this is measured useing a dummy round). Once you know your BL, CC and caliber from a chart or slide rule you can determine your burn rate and that is how choose your powder.
If what I have just posted sounds greek to you then use your books and publications, always confirm your load, start with the start load, load 5 then load 5 each of .5 grain incraments untill you get to the max load. go to your range and at 100 yards from the start load fire your 5 shots, (dont worry if the sights are a little off you are interested in groups at this point) take note of the size of the group and signs of preasure. Then do the same for the next incrament and the next ect. untill you notice the tightest group. You then have the most efficiant load combo of that powder and bullet for that rifle.
The books list 150 grain bullet in a 7mm rem mag useing IMR7828 SS, 63.4grn max 68.7 the vel 2851 to 3100fps. In my savage the tightest group is at 67.0 grns chrono at 3010fps so that is where I keep it.
Thanks for the explanation. There's certainly a lot more to this stuff that I realized when I started reloading.
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