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Rifles, Reloading, Optics, Equipment
Reloading
Pressure signs way below max load
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<blockquote data-quote="Coyote_Hunter" data-source="post: 1748041" data-attributes="member: 110773"><p>There are a variety of reasons pressure signs may show up before book max loads are reached.</p><ol> <li data-xf-list-type="ol">Differences in chamber dimensions including length of throat (shorter than test rifle throat).</li> <li data-xf-list-type="ol">Differences in shape and/or number of lands.</li> <li data-xf-list-type="ol">Not using exact same components used to develop book data (powder, primer, case brand).</li> <li data-xf-list-type="ol">Using components from batches of components different than used for book data. (This will ALWAYS be the case for consumers.)</li> <li data-xf-list-type="ol">Quality of barrel bore. (Smoothness and consistency of diameter. A tighter barrel will cause higher pressures.)</li> <li data-xf-list-type="ol">Using a different CBTO than was used for book data. (Since manufacturers list COAL rather than CBTO, a different CBTO is very likely.)</li> </ol><p></p><p>I have often found it difficult to reach book max powder charges. Speer, for one, reduced powder charges for the 7mm RM a year or two after I started reloading that cartridge back in the early 1980's. Using the original data resulted in short case life. The newer, reduced charge data resulted in much longer case life. Nosler max charges have been problematic for multiple cartridges. Some of the data for newer Hodgdon powders didn't result in pressure signs but max powder charges fell far short of advertised velocities. </p><p></p><p></p><p>One reason I prefer data with pressure data is that it provides one more data point in evaluating handloads.</p></blockquote><p></p>
[QUOTE="Coyote_Hunter, post: 1748041, member: 110773"] There are a variety of reasons pressure signs may show up before book max loads are reached. [LIST=1] [*]Differences in chamber dimensions including length of throat (shorter than test rifle throat). [*]Differences in shape and/or number of lands. [*]Not using exact same components used to develop book data (powder, primer, case brand). [*]Using components from batches of components different than used for book data. (This will ALWAYS be the case for consumers.) [*]Quality of barrel bore. (Smoothness and consistency of diameter. A tighter barrel will cause higher pressures.) [*]Using a different CBTO than was used for book data. (Since manufacturers list COAL rather than CBTO, a different CBTO is very likely.) [/LIST] I have often found it difficult to reach book max powder charges. Speer, for one, reduced powder charges for the 7mm RM a year or two after I started reloading that cartridge back in the early 1980’s. Using the original data resulted in short case life. The newer, reduced charge data resulted in much longer case life. Nosler max charges have been problematic for multiple cartridges. Some of the data for newer Hodgdon powders didn’t result in pressure signs but max powder charges fell far short of advertised velocities. One reason I prefer data with pressure data is that it provides one more data point in evaluating handloads. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Pressure signs way below max load
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