Boggy, ol' buddy, I think maybe the solution to your confusion may lie in the distinction between heat (in Btu) and temperature (in �F). Consider two logs of the same species of pine (your choice -- longleaf, shortleaf, slash, loblolly, or whatever else), exactly the same length and diameter.
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<br>Imagine (a) shredding one log into excelsior and striking a match to it, and (b) letting the other lie in the woods and rot. Both logs will put out the same number of Btu, but of course over strikingly different spans of time. Only a brass monkey or a cigar-store Indian lacks the imagination to see that the �F levels of the two are drastically different.
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<br>The high peak temperature concomitant with a high peak pressure, whatever the weight of the charge, is what affects the throat adversely. Lower that temperature, and even the far minor scrubbing action of the powder granules has less effect on the surface of the steel. Also, with the higher peak pressure, the increase in the temperature of the steel is more localized -- more tightly focused -- in the throat and early rifling.
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<br>At a lower peak temperature, a higher heat output (Btu) can be absorbed along more of the barrel's length without anything like the adverse effect of the higher peak temperature at the throat.
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<br>I've heated our homes with fuels from corn cobs to coal, natural gas, bottle gas, fuel oil, and several kinds of wood. It's been easy to notice that woods put out more heat (Btu) at lower temperatures (�F) and thus heat the house more evenly, and that some of the pitchier pines put out about the same amount of heat at higher temperatures. Good stove-fuel hardwoods (e g, oak) burn at much "cooler" �F than the pitchier pines but put out as much or more heat.
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<br>As I think I've already mentioned, the larger charge of a slower powder in my .220 Howell produces a lower peak pressure (therefore temperature) more gradually, and the gas thus produced maintains its pressure higher and longer. The peak is lower, longer, and less sharp, and the downslope is much less steep. So the larger charge does indeed produce more HEAT but at a significantly lower peak pressure and TEMPERATURE.
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<br>I hope this makes this mess a bit clearer to you -- but I bet that now somebody else in our crowd is more confused than he was.
