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Rifles, Reloading, Optics, Equipment
Reloading
The first sign of excessive pressure is...
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<blockquote data-quote="MontanaRifleman" data-source="post: 285989" data-attributes="member: 11717"><p>OK guys, once again I am not near the experienced handloader that many in this forum are. But I have to ask some questions about using velocity as your primary indicator of pressure.</p><p> </p><p>1) How do you know how accurate your chrony velocities are?</p><p> </p><p>2) If you are going to go by "published" data/velocites then what affect does using different primers, brass and/or seating depth have on the velocity?</p><p> </p><p>3) How different is the chanber, throat and bore of your rifle compared to the manufacturer's test rifle? Chamber, throat and bore dimensions can affect pressure which can and often are different from rifle to rifle.</p><p> </p><p>4) Different rifles will shoot the exact same ammo out of the same box or handload batch at different velocities.</p><p> </p><p>5) What about the case where two members here have reported getting 100-150 less fps while being at or over the "book" max in grains?</p><p> </p><p>6) Not all data matches. If you visit the Nosler and Hodgdon sites and check the data for 300 RUM/200 gr AB using IMR 7828, you will find a huge difference in their data.</p><p> </p><p>Hodgdon max -82.0gr/2857 fps</p><p>Nosler max - 87.5 gr/3102 fps</p><p> </p><p>Now that is a huge difference. The Hodgdom max is lower than the Nosler starting load. Which is right?</p><p> </p><p>Also, if you check the Hodgdon site for the 300 RUM/Retumbo/200 AB you will see that they list 95.5 gr as max with a velocity of 3048, and I have read numerous posts in here with members getting 3200 or more with that load.</p><p> </p><p>Finally, there are many cartridge/bullet/powder combinations for which there is no data - how do you determine max for those combinations?</p><p> </p><p>IMO, if you are going to go by the "book" data then you need to go by ALL of it. Same primers, same brass, same brass dimenssions, same barrel chambering, same seating depth (COAL), etc. Once you change any of that you throw your book off because it all has an effect on pressure and velocity and then you start guesssing.</p><p> </p><p>Not trying to pick a fight here with anyone, but I just dont see how any of these factors can be ignored. IMHO, the chrony can be a valuble tool but to say that it is the final or primary word on pressure I believe is a stretch.</p><p> </p><p>OK, I stand braced <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p><p> </p><p>-MR</p></blockquote><p></p>
[QUOTE="MontanaRifleman, post: 285989, member: 11717"] OK guys, once again I am not near the experienced handloader that many in this forum are. But I have to ask some questions about using velocity as your primary indicator of pressure. 1) How do you know how accurate your chrony velocities are? 2) If you are going to go by "published" data/velocites then what affect does using different primers, brass and/or seating depth have on the velocity? 3) How different is the chanber, throat and bore of your rifle compared to the manufacturer's test rifle? Chamber, throat and bore dimensions can affect pressure which can and often are different from rifle to rifle. 4) Different rifles will shoot the exact same ammo out of the same box or handload batch at different velocities. 5) What about the case where two members here have reported getting 100-150 less fps while being at or over the "book" max in grains? 6) Not all data matches. If you visit the Nosler and Hodgdon sites and check the data for 300 RUM/200 gr AB using IMR 7828, you will find a huge difference in their data. Hodgdon max -82.0gr/2857 fps Nosler max - 87.5 gr/3102 fps Now that is a huge difference. The Hodgdom max is lower than the Nosler starting load. Which is right? Also, if you check the Hodgdon site for the 300 RUM/Retumbo/200 AB you will see that they list 95.5 gr as max with a velocity of 3048, and I have read numerous posts in here with members getting 3200 or more with that load. Finally, there are many cartridge/bullet/powder combinations for which there is no data - how do you determine max for those combinations? IMO, if you are going to go by the "book" data then you need to go by ALL of it. Same primers, same brass, same brass dimenssions, same barrel chambering, same seating depth (COAL), etc. Once you change any of that you throw your book off because it all has an effect on pressure and velocity and then you start guesssing. Not trying to pick a fight here with anyone, but I just dont see how any of these factors can be ignored. IMHO, the chrony can be a valuble tool but to say that it is the final or primary word on pressure I believe is a stretch. OK, I stand braced :) -MR [/QUOTE]
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