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Barrel length and powder burn rates?

 
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  #57  
Old 06-08-2009, 09:20 AM
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Location: Texas
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Re: Barrel length and powder burn rates?

Quote:
Originally Posted by bookworm View Post
Well, I never thought my initial question would have sparked 7 pages of discussion. It was very informative to say the least - I learned a lot!

I think the bottom line for me is that I will keep my 26" barrel and H-1000 powder for now. If I get the accuracy I need out of that combo that is worth more than the little bit of mobility I might gain from a shorter barrel.

I wish I had the luxury of testing multiple barrel lengths with various powders to put some of these ideas through their paces. Sounds kinda fun.

In the mean time, if anyone has first hand experience (good or bad) with the combination I originally asked about, I'd be interested in your thoughts.

300 win mag
20" - 24" barrel
Slow powder (H-1000)
190gr match grade bullet
I think AJ cleared up the one issue very well so I will give you my opinion on your last question.

If you break it down to case capacity it is simple.

Cases that hold less than 50 grs of powder do well with short barrels, Because in order to reach
maximum pressures and velocities they use Fast burning powders and the gain per inch of
barrel over 20 to 22"inches is minimal .

Cases that hold less than 75 grs of powder are at there best when medium to slow burn rate
powders are used with 24" to 26" barrels 28 to30'' barrels can contribute to some increase in
velocity.

Cases that hold 75 to 100grs are at there best using slow burning powders and 26" to 30"in
barrels.

Cases that hold more than 100 grs of powder Need the slowest powders and can benefit from
30"inch + barrels . the maximum practical length that should be used is 34" inches because of
weight and performance.

The 300 win mag falls into the 75 gr group and 24" barrels would be considered the minimum
effective barrel length.

The 308,7/08 size cases work well with 18 to 20" barrels and are very portable, They like faster
burning powders like 4350,414,4064 and Varget.

There is one exception to this and it is the big bores (.375 and up ) they can burn huge amounts of
faster burning powder because of surface diameter of the bullets. But again they can and do use
short barrels.

There are a lot of cartridges that will work with 22" barrels ,and with the introduction of the short
magnums you can build a rifle that is short AND powerful,And because the short action saves
in overall length and uses less of the bore when chambered you can have a barrel 23" and have
the overall rifle length very short and handy.

I hope this answers your other question

J E CUSTOM
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Last edited by J E Custom; 06-08-2009 at 04:40 PM.
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  #58  
Old 06-08-2009, 11:41 PM
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Location: SW Idaho
Posts: 193
Re: Barrel length and powder burn rates?

Great reply JE.

Thanks for taking the time to help with my education.
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  #59  
Old 06-09-2009, 10:24 AM
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Re: Barrel length and powder burn rates?

i would not argue with any of you but i can say this. i don't normally ready argumentative threads. but this one has been so educational that i could not stop reading it. and if it was not for su37 being so hard headed i would not have learned what i did so all i have to say is thank you su37 you may not have learned anything but i have. so it was not a lost discussion after all.
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  #60  
Old 06-09-2009, 03:19 PM
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Posts: 985
Re: Barrel length and powder burn rates?

So I guess all those fireballs I see from my 458 socom weren't really there!! because all the powder burn't 18" back towards the chamber!
RR
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  #61  
Old 06-09-2009, 03:52 PM
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Posts: 247
Re: Barrel length and powder burn rates?

Not trying to stir it up here by any means.

To quote John Barsness

"The same powders that produce the most velocity with a longer barrel also produce the highest velocities with a shorter barrel. This is because almost all smokeless powder burns within a short distance in front of the chamber, contrary to what you may have heard.

In fact, the least velocity loss in shorter barrels is generally with heavier bullets and the slowest powders. "

Last edited by su37; 06-09-2009 at 04:06 PM.
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  #62  
Old 06-09-2009, 03:56 PM
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Join Date: Jan 2006
Posts: 247
Re: Barrel length and powder burn rates?

"So I guess all those fireballs I see from my 458 socom weren't really there!! because all the powder burn't 18" back towards the chamber!
RR"


And to quote John Barsness again,

"Actually the ball of flame is the hot gas from the powder reigniting when it hits the oxygen of the atmosphere, not still-burning powder.

Almost all the smokeless powder in a charge, say 99% plus, is consumed within at most a few inches of the case mouth, and often a lot sooner.

Of course the load has to create about the right pressure for the powder, as various powders are designed to burn best at different pressures. When the pressure is low for the powder--as in your Varget .45-70 load--then many powder granules simply won't burn. A few stay in the bore, but most are blown out the muzzle--but they aren't burning."
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  #63  
Old 06-09-2009, 04:17 PM
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Posts: 985
Re: Barrel length and powder burn rates?

Quote:
Originally Posted by su37 View Post

"Actually the ball of flame is the hot gas from the powder reigniting when it hits the oxygen of the atmosphere, not still-burning powder.
And I bet you wonder why noone pays attention to your posts, if something is burning, and goes out then as it gets air it re-ignites, what goes on? you better look up the definition of re-ignite, nah forget it, just remember, if your house catches on fire and the FD put it out, if it re-ignites, it ain't burning, don't worry about it.

Now I don't run a nuclear reactor in my spare time but I'm not stupid, I know that powder doesn't actualy burn so to speak, neither does wood for that matter, heat converts it to gases that burn. and powder burns more violently when its under pressure, thats why you can pour a lb of powder out in the yard and watch it burn a pretty blue flame. if the gasses made by the powders ignition re-ignite, then the powder is still doing what it sposed to do which is make pressure (if it can) and your wasteing powder, by using too slow of powder for the application, if its still making pressure the gasses are burning, Ron white said it best.......it can't be fixed!
RR
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Last edited by Ridge Runner; 06-09-2009 at 04:26 PM.
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