just another tool to check est. pressure, sure tells you if your on the outer edge of safe.
Flattened Primers? Help?
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just another tool to check est. pressure, sure tells you if your on the outer edge of safe.
Reloader222
Well-Known Member
I would say if it is inconsitent with the same load, then you need to check for veriables. I had found 2 out of 10 case with the same load giving me flattened primers. The weight and volume of case were not significant different. The flattened primers also occured in cases with bigger volumes. I had then checked for donuts and yes, there it was! Check for donuts by inserting a bullet in the case neck after the case has been fired. If it goes through there is no donut, if it does not want to go through there is a donut. The donut must be cut out before sizing with a case neck reamer (Foster).
boomtube
Well-Known Member
"just another tool to check est. pressure, sure tells you if your on the outer edge of safe."
No, it doesn't, and that's my point.
Bart's experience with proof loads supports what I'm saying - primers do NOT automatically tell us much of anything about pressure. Our pressures may be quite modest and still produce very flat primers to frighten us. OR the pressure can be quite high but the primers look near normal and give us a dangerous false sense of security; that's the part that worries me when I read so many guys suggesting it is a viable pressure indicator. I'm not saying to pay no attention to fired primers, they can tell us a lot, but not much of it's directly related to chamber pressure.
Larry, you are correct that 'we' have been 'using' primers to indicate pressure for a very long time BUT in recent decades we have been kidding ourselves. Primer reading started when they all had domed - concave - tops so flattening actually meant something that our modern already flat-topped primers don't show very well. Anyone who uses your excellant Innovative Tech dial indicator case headspace tool, etc, to measure and match fired and sized shoulder locations will see very little primer flattening because they won't be able to back out of the case enough to squish flat when the case head pushes back to the breech.
A chorongraph is no pressure gage but we can be quite sure that if a given bullet weight over a specific quanity of a given powder is going much faster for us than it did for our book makers we are producing a higher pressure than the bookies got. IF that's worth being concerned about.
!!
No, it doesn't, and that's my point.
Bart's experience with proof loads supports what I'm saying - primers do NOT automatically tell us much of anything about pressure. Our pressures may be quite modest and still produce very flat primers to frighten us. OR the pressure can be quite high but the primers look near normal and give us a dangerous false sense of security; that's the part that worries me when I read so many guys suggesting it is a viable pressure indicator. I'm not saying to pay no attention to fired primers, they can tell us a lot, but not much of it's directly related to chamber pressure.
Larry, you are correct that 'we' have been 'using' primers to indicate pressure for a very long time BUT in recent decades we have been kidding ourselves. Primer reading started when they all had domed - concave - tops so flattening actually meant something that our modern already flat-topped primers don't show very well. Anyone who uses your excellant Innovative Tech dial indicator case headspace tool, etc, to measure and match fired and sized shoulder locations will see very little primer flattening because they won't be able to back out of the case enough to squish flat when the case head pushes back to the breech.
A chorongraph is no pressure gage but we can be quite sure that if a given bullet weight over a specific quanity of a given powder is going much faster for us than it did for our book makers we are producing a higher pressure than the bookies got. IF that's worth being concerned about.
!!
Innovative
Well-Known Member
....................... oh boy ..........................
Reloader222
Well-Known Member
"just another tool to check est. pressure, sure tells you if your on the outer edge of safe."
No, it doesn't, and that's my point.
Bart's experience with proof loads supports what I'm saying - primers do NOT automatically tell us much of anything about pressure. Our pressures may be quite modest and still produce very flat primers to frighten us. OR the pressure can be quite high but the primers look near normal and give us a dangerous false sense of security; that's the part that worries me when I read so many guys suggesting it is a viable pressure indicator. I'm not saying to pay no attention to fired primers, they can tell us a lot, but not much of it's directly related to chamber pressure.
Larry, you are correct that 'we' have been 'using' primers to indicate pressure for a very long time BUT in recent decades we have been kidding ourselves. Primer reading started when they all had domed - concave - tops so flattening actually meant something that our modern already flat-topped primers don't show very well. Anyone who uses your excellant Innovative Tech dial indicator case headspace tool, etc, to measure and match fired and sized shoulder locations will see very little primer flattening because they won't be able to back out of the case enough to squish flat when the case head pushes back to the breech.
A chorongraph is no pressure gage but we can be quite sure that if a given bullet weight over a specific quanity of a given powder is going much faster for us than it did for our book makers we are producing a higher pressure than the bookies got. IF that's worth being concerned about.
Very well said and true!!
boomtube
Well-Known Member
As a off-topic side issue, I disagree that Federal primers are "soft".
Fed. uses a more sensitive priming compound that will detonate more easily than others and that's why they are packaged in individual pockets in the trays. I suspect that sensitivity is why 'conventional wisdom' says they are softer. BUT, I've found Federals don't crater in my old 1903-A3 with a slightly overly large firing pin hole so it's not likely they are very soft! And, over the last 45 years, I've had fewer failure-to-fire events with Fed primers so they are always my first choice if they shoot well.
(I never load 'down' for better accuracy, if I can't get excellant accuracy with top loads with my first powder choice I try other powders until I get both accuracy AND speed!)
Fed. uses a more sensitive priming compound that will detonate more easily than others and that's why they are packaged in individual pockets in the trays. I suspect that sensitivity is why 'conventional wisdom' says they are softer. BUT, I've found Federals don't crater in my old 1903-A3 with a slightly overly large firing pin hole so it's not likely they are very soft! And, over the last 45 years, I've had fewer failure-to-fire events with Fed primers so they are always my first choice if they shoot well.
(I never load 'down' for better accuracy, if I can't get excellant accuracy with top loads with my first powder choice I try other powders until I get both accuracy AND speed!)
Feds primers use the same material as everyone else. Their cup thickness is thinner on
the small primers (200's) though. This chart bares reposting every year or so. I am sure they are
easier to ignite with a lighter strike as a result.
the small primers (200's) though. This chart bares reposting every year or so. I am sure they are
easier to ignite with a lighter strike as a result.
"just another tool to check est. pressure, sure tells you if your on the outer edge of safe."
No, it doesn't, and that's my point.
Bart's experience with proof loads supports what I'm saying - primers do NOT automatically tell us much of anything about pressure. Our pressures may be quite modest and still produce very flat primers to frighten us. OR the pressure can be quite high but the primers look near normal and give us a dangerous false sense of security; that's the part that worries me when I read so many guys suggesting it is a viable pressure indicator. I'm not saying to pay no attention to fired primers, they can tell us a lot, but not much of it's directly related to chamber pressure.
Larry, you are correct that 'we' have been 'using' primers to indicate pressure for a very long time BUT in recent decades we have been kidding ourselves. Primer reading started when they all had domed - concave - tops so flattening actually meant something that our modern already flat-topped primers don't show very well. Anyone who uses your excellant Innovative Tech dial indicator case headspace tool, etc, to measure and match fired and sized shoulder locations will see very little primer flattening because they won't be able to back out of the case enough to squish flat when the case head pushes back to the breech.
A chorongraph is no pressure gage but we can be quite sure that if a given bullet weight over a specific quanity of a given powder is going much faster for us than it did for our book makers we are producing a higher pressure than the bookies got. IF that's worth being concerned about.
so, if i'm reading waaaaaay over listed fps, my crono isnt ANOTHER TOOL to help diagnose "pressure" ?
Yes.
Chrono's only tell you how fast the bullet goes through them. One can reasonably assume that with a given load using different charge weights that faster velocities happen with higher peak pressures. But one doesn't know what pressure they're peaking at.
Ya'll may be too smart for your own good. I have yet to hear any thoughts on a resolution to my questions. Ya'll are too busy in a ****in match to address the topic at hand. Its okay, I'll just start a new thread.
Thanks for the input thus far.
Thanks for the input thus far.
rscott5028
Well-Known Member
I don't think your primers are flattened too much.
I don't think you have a sizing problem.
If you want to measure and be consistent, I would recommend one of several gauges to start with such as the Hornady Lock-n-Load Headspace adapters that fit onto your calipers. This will allow you to measure your cartridge from the head to the headspace datum line on the shoulder. Once you have your dies set, then you can lock the ring in place in order to have a repeatable setting.
If you want to take it a step further, then remove the ejector from your bolt and add one layer of scotch tape at a time to the case head and check for feel. Measure the tape thickness, add it all up, and that'll give you a rouch measurement of your chamber headspace.
In short, one or two layers of scotch tape is "usually" about .001-.002" which is fine for a hunting rifle. Some will disagree about using scotch tape as it compresses and they are correct. It's not a complete substitute for proper headspace gauges. But, it'll provide one piece of information that you currently do not have.
Don't forget to replace the ejector in your bolt when you're done.
...or, you can simply neck size and your cartridge will be just about right for a few firings before you need to bump the shoulder or FL size.
-- richard
+1 you are correct.
