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Joined: Jan 2002
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Sidelock
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My head is starting to hurt. The only pressure reading a shooter is interested in at a given location (and he doesn't really care about how long it took to get there) is the highest reading at that location. Therefore, once you've talked about the highest reading in the entire barrel--which is what we get from reloading manuals when they give a pressure of a specific load--you don't need to use any adjective, PERIOD.

One more time, here's my example, simple and straightforward: "Load X developed its peak pressure of 8,323 psi at 1.3" from the breech. At 3", the pressure reading had dropped to 6,724 psi; at 6", to 5,438 psi; at 12", to 4,392 psi . . . " etc. Why complicate things by talking about a maximum at any location other than the overall peak pressure, when the only figure anyone is interested in (except perhaps engineers) is the highest pressure at a given location? Hell, why not throw in the fact that there's no pressure at all before the gun is fired--which means that any increase at all could be called a peak? Even though that "peak" in fact represents a DECREASE in pressure from the previous "peak", back closer to the breech? If all I know is the information I presented in my example above, then I can make myself a little graph (if I chose to do so), or the individual presenting the information can make the graph--as Bell did in his article, and as Dupont did in their tests--and compare the "rate of decay" in pressure between specific loads. What more do I need to know, and why would I need to know it? If my concern is protecting my old and thin-walled barrels from excess pressure, that information will allow me to choose between loads with various peak pressures, as well as between loads with similar peak pressures but different rates of decay. If I'm worried about a pressure of 6700 psi at 6" from the breech, produced by a load with a peak pressure of 8500 psi, then I can look for another load with a similar (or lower) peak pressure which also has a lower pressure at 6". Anything else is irrelevant, and anything else using "peak", "location peak", or "location maximum" is potentially confusing--because I, as a shooter, have no interest whatsoever in any pressure readings at a given location other than the highest pressure reading at that given location.

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Sidelock
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Bottom line here is Rocketman gave us a very good understanding of what takes place.

"Others" just complained of the noise.

Me, I just clap my hands & Stir the Pot.

GO Rocketman!!!!


Miller/TN
I Didn't Say Everything I Said, Yogi Berra
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Larry,

I enjoy reading your posts and the knowledge which you share.

Toward this thread, I found Rocketman's explaination of the pressure curve produced in a shotgun barrel to be in the standard parlance of gun writing. The use of the term peak or maximum may be an unnecessary adjective but is certainly neither wrong nor confusing to most. I use such terms in reports so that my message is not taken out of context by others. "The pressure developed was X psi at 6" from the breach with a certain load". One might ask, "Was that the peak (maximum) pressure?" Using the term peak or maximum clarifies the message.

If someone as knowledgable as Rocketman takes the time to share his knowledge with us, then perhaps we should appreciate him for that.

Respectfully,
Mark

Last edited by MarkOue; 06/11/11 09:22 AM.

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It's all been a good discussion -- thanks to all the participants!

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