case head expansion when working up loads
- Thread starter RW
- Start date
Before the Internet:
Today it is loud and rude.
Before the Internet .00025", on the Internet there is a big problem with micrometers. I had a micrometer that measured .000005", it was useless, I removed the electronics and installed a dial indicator on the stylist. Now? It is a 11" height gage.
The .00025" number was obtained by firing new/factory ammo, the case head diameter had to be measured before and again after.
then there is the primer pocket and flash hole, who measures? If the case head expands the flash hole expands, then it is a matter of measuring the diameter of the flash hole. I have a flash hole gage.
F. Guffey
Today it is loud and rude.
Before the Internet .00025", on the Internet there is a big problem with micrometers. I had a micrometer that measured .000005", it was useless, I removed the electronics and installed a dial indicator on the stylist. Now? It is a 11" height gage.
The .00025" number was obtained by firing new/factory ammo, the case head diameter had to be measured before and again after.
then there is the primer pocket and flash hole, who measures? If the case head expands the flash hole expands, then it is a matter of measuring the diameter of the flash hole. I have a flash hole gage.
F. Guffey
CatShooter
Case head expansion is not a reliable indicator of pressure.
Case hardness is not held to any standard, and can vary by a 2:1 ratio.
Learn to read primers, extraction, and the case face.
(And don't worry about fguffey, nobody here understands a word he says - he talks to people that the rest of can't hear or see
)
Case hardness is not held to any standard, and can vary by a 2:1 ratio.
Learn to read primers, extraction, and the case face.
(And don't worry about fguffey, nobody here understands a word he says - he talks to people that the rest of can't hear or see
)bigedp51
RW
Just the other day CatShooter posted brass hardness figures for different brands of cases with Lake City being the hardest and Remington being the softest of the cases he measured.
(The rat bastard commie pinko pervert forgot to measure Federal cases which might be even softer) :
Below is an excerpt from CatShooters posting on brass hardness.
The actual Hardness measurements were (.062"x100kg, Rockwell "B")
LC 2008 = 96
Lapua 223 Match = 86
Norma 30-06 - 76 (added n Dec -'14)
Winchester 223 = 69
Norma .220 Swift = 64 (added in Dec '14)
Remington "R-P" = 49
For all you guys that have been saying that Winchester cases were tougher than Remington... you are vindicated, they are a lot tougher!... 40% tougher
For all you guys that think Lake City is surplus junk, nothing could be further from the truth. It is some of the most bestest brass made (it is paid for by the tax payer), so enjoy it!!!
LC and Lapua are the "The pick of the litter"!
The Hornady manual states the following:
"And even half of one thousandth of an inch (.0005") increase in the diameter of the case head is an indication of high pressure."
http://www.hornady.com/ballistics-resource/internal
I think the standard for base expansion is .001, BUT I cant find a test done listing actual chamber pressure and base expansion.
But as you can see above and from other postings here that case hardness and base expansion are not written in stone. And the limiting factor for pressure is the brass strength itself. Bottom line you need to read all your cases signs for pressure but none of them are a direct correlation to "actual" true chamber pressure. Meaning a load worked up with Remington brass will indicate high pressure long before Lake City or Lapua brass will shows signs.
Below is why reading primers can be deceiving, the drawing below is the submission drawing to the military for the CCI #34 primer. Please note the base of the primer cup is thicker than its side walls and would show less signs of pressure than standard cups of .025 or thinner cups.
A chain is only as strong as its weakest link!
P.S. Sorry CatShooter I didn't mean to knock you out of this posting.
Just the other day CatShooter posted brass hardness figures for different brands of cases with Lake City being the hardest and Remington being the softest of the cases he measured.
(The rat bastard commie pinko pervert forgot to measure Federal cases which might be even softer) :
Below is an excerpt from CatShooters posting on brass hardness.
The actual Hardness measurements were (.062"x100kg, Rockwell "B")
LC 2008 = 96
Lapua 223 Match = 86
Norma 30-06 - 76 (added n Dec -'14)
Winchester 223 = 69
Norma .220 Swift = 64 (added in Dec '14)
Remington "R-P" = 49
For all you guys that have been saying that Winchester cases were tougher than Remington... you are vindicated, they are a lot tougher!... 40% tougher
For all you guys that think Lake City is surplus junk, nothing could be further from the truth. It is some of the most bestest brass made (it is paid for by the tax payer), so enjoy it!!!
LC and Lapua are the "The pick of the litter"!
The Hornady manual states the following:
"And even half of one thousandth of an inch (.0005") increase in the diameter of the case head is an indication of high pressure."
http://www.hornady.com/ballistics-resource/internal
I think the standard for base expansion is .001, BUT I cant find a test done listing actual chamber pressure and base expansion.
But as you can see above and from other postings here that case hardness and base expansion are not written in stone. And the limiting factor for pressure is the brass strength itself. Bottom line you need to read all your cases signs for pressure but none of them are a direct correlation to "actual" true chamber pressure. Meaning a load worked up with Remington brass will indicate high pressure long before Lake City or Lapua brass will shows signs.
Below is why reading primers can be deceiving, the drawing below is the submission drawing to the military for the CCI #34 primer. Please note the base of the primer cup is thicker than its side walls and would show less signs of pressure than standard cups of .025 or thinner cups.
A chain is only as strong as its weakest link!
P.S. Sorry CatShooter I didn't mean to knock you out of this posting.
This is the second time in a few days where brass hardness and difference has came up.I am curious why is nickel plated brass not in any of the equations.I just skimed turned the necks on some np rem brass last night and it is diffinitly harder brass.
CatShooter
hunter243sgk said:
What were your hardness measurements??
The hardness in the neck has no relationship to the head, so it means nothing. Plating does not change the hardness of the neck.
The first time I skim them I do it so lite of a skim I don't measure neck thickness.After they are shot once then I will measure them and then re-skim as necessary.I don't know that this is the best way or not but the way I am doing it.Why do you ask?
CatShooter
I wasn't asking about the thickness I was asking about the hardness, cuz I never heard of, "definitely harder" as a hardness measurement.
Sorry for the mis-understanding.I guess my mouth over loaded my a$$.I don't have a way to measure true hardness like you do.I based it on how they felt going in my dies and scimming my necks.Then I crushed the mouth of one with my thumb then crushed a win.Yes pretty crude I know.But have you tested any with your tools?
CatShooter
hunter243sgk said:
Nickle plating is only a few thou and doesn't affect the hardness of brass...
I really cant argue that point sence I don't have a way to get the numbers.I did post it wrong what I tested it againt was regular rem verses rem plated.Maybe it was an oddity but but istill think the np was stiffer.But I have been wrong many times in the past.Where could I have those two batches checked for hardness?
CatShooter
hunter243sgk said:
You have to understand - the hardness of a neck is not dependent on plating - neck hardness' change all the time for many reasons.
You could buy a box as ammo and measure the neck hardness today, and six months from now, buy the same brand and the necks would be different - but the heads would be very close.
If you load cases, the neck keeps getting harder and harder until it splits or you anneal it (and then it starts all over)....
Getting back to the original question, are people asking about expansion measured at the base of the case body above the extractor groove or the expansion of the groove itself? I do feel that expansion of the groove is a great indicator of the upper limits of pressure for any particular brand of brass. In my experience, once the groove grows by 0.0005 inches on the first firing, the rate of expansion increases rapidly and the primer pockets start to go south in a hurry. This is usually accompanied by all of the primer, bolt lift and extraction signs as well. Otherwise, my experience with this method seems to line up pretty well with Catshooter's hardness measurements and I have certainly done some things with LC 308 brass that can't be done with other brands. But that Lapua small primer Palma 308 brass is the best I've tried.
Won't the chamber dimensions affect head expansion? I think a semi-auto or military rifle have a bigger chamber? Like someone said look at all of the signs not just one. If you don't shoot stiff charges you should never have a problem. It's been a long time since I saw a drawing of case fit in the chamber. The entire case head is not in the chamber. It's beyond the extraction groove that it's in the chamber. Does anyone have a typical drawing showing the case fit in the chamber?
Where I used to work I cross-sectioned military parts and measured plating thickness. Never measured a Ni plated cartridge. The Cd and Cr plated parts I measured ran in the area of 1 to 2 ten thou. thick. This is all of the thickness needed for corrosion protection or wear resistance on some parts.
Where I used to work I cross-sectioned military parts and measured plating thickness. Never measured a Ni plated cartridge. The Cd and Cr plated parts I measured ran in the area of 1 to 2 ten thou. thick. This is all of the thickness needed for corrosion protection or wear resistance on some parts.
The solid case head is not supported in most designs. Where the head is not supported the case provides the strength to resist case head expansion.
For a Mauser about .110 of the case head is not in the chamber. The chamber edge is often radiused making the unsupported lenght about .120 or so. The case wall up to the solid head is free to expand until it is limited by the chamber walls. The solid head has to hold the pressure with no support. When the head starts yielding (permanent deformation) the elastic limit of the brass has been exceeded. If you continue expanding the case head you will get blown primers and eventually blown primer pockets.
For a Mauser about .110 of the case head is not in the chamber. The chamber edge is often radiused making the unsupported lenght about .120 or so. The case wall up to the solid head is free to expand until it is limited by the chamber walls. The solid head has to hold the pressure with no support. When the head starts yielding (permanent deformation) the elastic limit of the brass has been exceeded. If you continue expanding the case head you will get blown primers and eventually blown primer pockets.
Webster said:
Re: Case head protrusion and unsupported case head
Case head protrusion, .110", always forgotten is head space clearance. The problem not many can determine if the clearance is at the shoulder of the case and chamber of between the case head and bolt face. In the perfect world I have .005" clearance. Then there is the Mauser, it is a control feed.
Going back to the beginning as in before the Internet. With factory ammo and factory loads reloaders were told to expect .00025" case head expansion. Then there were other details but that was before the Internet.
F. Guffey
Case head protrusion, .110", always forgotten is head space clearance. The problem not many can determine if the clearance is at the shoulder of the case and chamber of between the case head and bolt face. In the perfect world I have .005" clearance. Then there is the Mauser, it is a control feed.
Going back to the beginning as in before the Internet. With factory ammo and factory loads reloaders were told to expect .00025" case head expansion. Then there were other details but that was before the Internet.
F. Guffey
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