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Rifles, Reloading, Optics, Equipment
Reloading
excess pressure?
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<blockquote data-quote="Reloader222" data-source="post: 611061" data-attributes="member: 25295"><p>I copied this from some site - sorry I did not make a note of where to find:</p><p> </p><p><strong><span style="color: black"><span style="font-family: 'Times New Roman'"><span style="font-size: 12px">"The way to tell if the pressure is low:</span></span></span></strong></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">1. Unburned powder in the barrel pretty much always means low.</span></span></p><p> </p><p><span style="font-family: 'Times New Roman'"><span style="color: black">2. Primer backed out of the primer pocket (i.e., not flattened) usually means low.</span></span></p><p> </p><p><span style="font-family: 'Times New Roman'"><span style="color: black">3. What does the manual say? If you're at the lower end of recommended loads, then the pressure is probably low.</span></span></p><p> </p><p><span style="font-family: 'Times New Roman'"><span style="color: black"><span style="font-size: 15px"><span style="color: black">The way to tell if the pressure is high:</span></span></span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">1. Sticky ejection. If ejection is sticky in a clean firearm in good mechanical condition then the pressure is high.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">2. Primer flattened clear out to the edges.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">3. Loads at the upper end of those recommended in a manual.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">4. Blown or pierced primers.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">5. Rapidly expanding primer pockets on reloading and/or poor brass life. Defective brass can also cause these signs.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">6. Group sizes that have been decreasing as a load is increased and then start to widen again.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">7. Cases from a semiauto that have been landing in about the same place and then start to be thrown erratically to markedly different places.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">8. Cases from a semiauto on which scuff marks start to appear on the body of ejected cases.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">9. Extractor marks swaged into the case head.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">I've probably missed some.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">You have to know an individual gun as well because different guns and different actions types will show signs of pressure in different sequences.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">Now I'm sure you've all heard about light powder charges in large capacity cases using slow powders (it can happen with fast powders as well). The result can be high pressure signs like flattened primers, splintered stocks and sticky ejection as well as hang fires. What happens is that the bullet starts to engage the bore but the pressure isn't quite high enough to push it clear through. The powder is still burning and the pressure keeps rising until it's high enough to push the bullet that was kind of stuck, out of the bore. As we all know, it takes quite a bit less pressure to get a bullet going down the bore with a little jump between the bullet and the lands than to start a bullet that is already engaging the lands. You might think of it as the closest you can get to a squib load (a load with which the bullets remain in the bore) without having a squib load.</span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">So, in the latter case, though the load is light, the pressure is quite high. In other words, case head smearing, sticky bolt lift, very flattened primers are signs of high pressure even if the powder charge is low unless the chamber is dirty or there is some mechanical defect in the firearm."</span></span></p><p> </p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'">According to my observation you do not have a high pressure sign. The primer is not smeared in the primer pocket and is not flattened. I would say this is a good pressure load given that all other conditions are favourable. Lastly when you press the primer out and you look at it with multiplyer glasses and you see a "flat-hat-top" you have high pressure, but when the top of the "hat" is still rounded, pressure is still fine.</span></span></p></blockquote><p></p>
[QUOTE="Reloader222, post: 611061, member: 25295"] I copied this from some site - sorry I did not make a note of where to find: [B][COLOR=black][FONT=Times New Roman][SIZE=3]"The way to tell if the pressure is low:[/SIZE][/FONT][/COLOR][/B] [COLOR=black][FONT=Times New Roman]1. Unburned powder in the barrel pretty much always means low.[/FONT][/COLOR] [FONT=Times New Roman][COLOR=black]2. Primer backed out of the primer pocket (i.e., not flattened) usually means low.[/COLOR][/FONT] [FONT=Times New Roman][COLOR=black]3. What does the manual say? If you're at the lower end of recommended loads, then the pressure is probably low.[/COLOR][/FONT] [FONT=Times New Roman][COLOR=black][SIZE=4][COLOR=black]The way to tell if the pressure is high:[/COLOR][/SIZE][/COLOR][/FONT] [COLOR=black][FONT=Times New Roman]1. Sticky ejection. If ejection is sticky in a clean firearm in good mechanical condition then the pressure is high.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]2. Primer flattened clear out to the edges.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]3. Loads at the upper end of those recommended in a manual.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]4. Blown or pierced primers.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]5. Rapidly expanding primer pockets on reloading and/or poor brass life. Defective brass can also cause these signs.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]6. Group sizes that have been decreasing as a load is increased and then start to widen again.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]7. Cases from a semiauto that have been landing in about the same place and then start to be thrown erratically to markedly different places.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]8. Cases from a semiauto on which scuff marks start to appear on the body of ejected cases.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]9. Extractor marks swaged into the case head.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]I've probably missed some.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]You have to know an individual gun as well because different guns and different actions types will show signs of pressure in different sequences.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]Now I'm sure you've all heard about light powder charges in large capacity cases using slow powders (it can happen with fast powders as well). The result can be high pressure signs like flattened primers, splintered stocks and sticky ejection as well as hang fires. What happens is that the bullet starts to engage the bore but the pressure isn't quite high enough to push it clear through. The powder is still burning and the pressure keeps rising until it's high enough to push the bullet that was kind of stuck, out of the bore. As we all know, it takes quite a bit less pressure to get a bullet going down the bore with a little jump between the bullet and the lands than to start a bullet that is already engaging the lands. You might think of it as the closest you can get to a squib load (a load with which the bullets remain in the bore) without having a squib load.[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]So, in the latter case, though the load is light, the pressure is quite high. In other words, case head smearing, sticky bolt lift, very flattened primers are signs of high pressure even if the powder charge is low unless the chamber is dirty or there is some mechanical defect in the firearm."[/FONT][/COLOR] [COLOR=black][FONT=Times New Roman]According to my observation you do not have a high pressure sign. The primer is not smeared in the primer pocket and is not flattened. I would say this is a good pressure load given that all other conditions are favourable. Lastly when you press the primer out and you look at it with multiplyer glasses and you see a "flat-hat-top" you have high pressure, but when the top of the "hat" is still rounded, pressure is still fine.[/FONT][/COLOR] [/QUOTE]
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