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Rifles, Reloading, Optics, Equipment
Reloading
Flattened Primer Question for 300 RUM
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<blockquote data-quote="The Gerk" data-source="post: 751505" data-attributes="member: 62597"><p><span style="font-size: 12px"><span style="font-family: 'Arial'">On the surface with the information provided the load (charge weight) does not seem excessive but as you know this can mean little depending on other factors, especially when working in the upper spectrum of the load range.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">(I have many rifles that reach their maximums before most published data maximums would indicate.)</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">"Flattening primer appearance" can mean many different things to many different people</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">It really comes into play when you "know" your rifle.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">Like, is there still some exposed radius (curve) to the edge of the primer face?</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">Or is it completely flattened to the point this is completely eliminated or even has flowed over the case head. </span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">You did not list your starting charge weight on the "work up"</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">Since we <em>know</em> you used a proper work up routine it would have been more productive to monitor the primer condition and make notes on the way up as charge weights were increased every tenth or two tenths.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">This would be preferred over doing it in reverse (backing down) because the cases will have more cycles on them and this alone can skew the "readings"</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">You list a COL of 3.690"</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">This while on the long side (SAAMI MAX COL is 3.600") this may or may not contribute to the condition but do you know the distance from the Berger's ogive contact point to the lands when chambered?</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">This would be helpful to know so it could be placed in the evaluation.</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">You didn't mention how you size these</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">Did you FL resize the cases or neck size only on fire-formed cases?</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">This can make huge difference in primer appearance </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">If you FL resized the cases there will be several thousandths added to the "actual headspace" tolerance when the cartridge is chambered.</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">What can happen here is, when the firing pin strikes the primer the cartridge is driven forward until the shoulder contacts the chamber, on ignitions the cartridge is slammed back onto the bolt face, while the cartridge under ignition was expanding during the pressure generation cycle the primer may be forced rearward several thousandths before it can be stopped by the bolt face </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">Since the pressure is now equalized in the chamber the primer will not get "reseated" it will flatten. </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">Obviously this is all taking place in milliseconds but the dimensions do change under this scenario </span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">You usually don't see this condition on fire-formed cases because the case has been pressure formed to the chamber so the case cannot be moved forward by the energy of the firing pin.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">(One of the reasons we fire-form the cases)</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">While you may be safe, if it were me I would want to know why the primers were flattening</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">Because if it is from something improper or a high pressure issue the current load configuration could come back to haunt you.</span></span></p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">While currently not problematic, it could be something as simple as you using this load on a hot day and the high temps combined with the "problem" (whatever it is) send the spike over the limit of the case and or primer and you may have more than a stuck bolt to deal with.</span></span></p><p> </p><p><span style="font-size: 12px"><span style="font-family: 'Arial'">Good Luck </span></span></p></blockquote><p></p>
[QUOTE="The Gerk, post: 751505, member: 62597"] [SIZE=3][FONT=Arial]On the surface with the information provided the load (charge weight) does not seem excessive but as you know this can mean little depending on other factors, especially when working in the upper spectrum of the load range.[/FONT][/SIZE] [SIZE=3][FONT=Arial](I have many rifles that reach their maximums before most published data maximums would indicate.)[/FONT][/SIZE] [SIZE=3][FONT=Arial]“Flattening primer appearance” can mean many different things to many different people[/FONT][/SIZE] [SIZE=3][FONT=Arial]It really comes into play when you “know” your rifle.[/FONT][/SIZE] [SIZE=3][FONT=Arial]Like, is there still some exposed radius (curve) to the edge of the primer face?[/FONT][/SIZE] [SIZE=3][FONT=Arial]Or is it completely flattened to the point this is completely eliminated or even has flowed over the case head. [/FONT][/SIZE] [SIZE=3][FONT=Arial]You did not list your starting charge weight on the “work up”[/FONT][/SIZE] [SIZE=3][FONT=Arial]Since we [I]know[/I] you used a proper work up routine it would have been more productive to monitor the primer condition and make notes on the way up as charge weights were increased every tenth or two tenths.[/FONT][/SIZE] [SIZE=3][FONT=Arial]This would be preferred over doing it in reverse (backing down) because the cases will have more cycles on them and this alone can skew the “readings”[/FONT][/SIZE] [SIZE=3][FONT=Arial]You list a COL of 3.690”[/FONT][/SIZE] [SIZE=3][FONT=Arial]This while on the long side (SAAMI MAX COL is 3.600”) this may or may not contribute to the condition but do you know the distance from the Berger’s ogive contact point to the lands when chambered?[/FONT][/SIZE] [SIZE=3][FONT=Arial]This would be helpful to know so it could be placed in the evaluation.[/FONT][/SIZE] [SIZE=3][FONT=Arial]You didn’t mention how you size these[/FONT][/SIZE] [SIZE=3][FONT=Arial]Did you FL resize the cases or neck size only on fire-formed cases?[/FONT][/SIZE] [SIZE=3][FONT=Arial]This can make huge difference in primer appearance [/FONT][/SIZE] [SIZE=3][FONT=Arial]If you FL resized the cases there will be several thousandths added to the "actual headspace" tolerance when the cartridge is chambered.[/FONT][/SIZE] [SIZE=3][FONT=Arial]What can happen here is, when the firing pin strikes the primer the cartridge is driven forward until the shoulder contacts the chamber, on ignitions the cartridge is slammed back onto the bolt face, while the cartridge under ignition was expanding during the pressure generation cycle the primer may be forced rearward several thousandths before it can be stopped by the bolt face [/FONT][/SIZE] [SIZE=3][FONT=Arial]Since the pressure is now equalized in the chamber the primer will not get “reseated” it will flatten. [/FONT][/SIZE] [SIZE=3][FONT=Arial]Obviously this is all taking place in milliseconds but the dimensions do change under this scenario [/FONT][/SIZE] [SIZE=3][FONT=Arial]You usually don’t see this condition on fire-formed cases because the case has been pressure formed to the chamber so the case cannot be moved forward by the energy of the firing pin.[/FONT][/SIZE] [SIZE=3][FONT=Arial](One of the reasons we fire-form the cases)[/FONT][/SIZE] [SIZE=3][FONT=Arial]While you may be safe, if it were me I would want to know why the primers were flattening[/FONT][/SIZE] [SIZE=3][FONT=Arial]Because if it is from something improper or a high pressure issue the current load configuration could come back to haunt you.[/FONT][/SIZE] [SIZE=3][FONT=Arial]While currently not problematic, it could be something as simple as you using this load on a hot day and the high temps combined with the “problem” (whatever it is) send the spike over the limit of the case and or primer and you may have more than a stuck bolt to deal with.[/FONT][/SIZE] [SIZE=3][FONT=Arial]Good Luck [/FONT][/SIZE] [/QUOTE]
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Flattened Primer Question for 300 RUM
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