Case web expansion?
- Thread starter thefitter
- Start date
CatShooter
thefitter said:
When the primers are loose.
bigedp51
thefitter said:
That would depend on the harness of the brass at its base, and when the base expands over .0005 to .001 it shows you you are exceeding the elastic limits of the brass.
A .222 at a chamber pressure of 46,000 cup or 50,000 psi and reloaded to these pressure limits is not noted for case head expansion and loose primer pockets.
And remembering this is why my .223/5.56 cases last so long when reloaded.
bigedp51
thefitter
Question: What type/make resizing die are you using.
The reason I ask is you say the primers are still tight but you have heavy bolt lift. So are you getting adequate shoulder bump and sizing at the base of the case.
We live in a plus and minus manufacturing world and no two dies and chambers are exactly the same. I have standard dies that size the base of the case smaller than a small base die does. So is there a possibility your die is on the plus side in diameter or is the problem just adding a shade more shoulder bump.
Question: What type/make resizing die are you using.
The reason I ask is you say the primers are still tight but you have heavy bolt lift. So are you getting adequate shoulder bump and sizing at the base of the case.
We live in a plus and minus manufacturing world and no two dies and chambers are exactly the same. I have standard dies that size the base of the case smaller than a small base die does. So is there a possibility your die is on the plus side in diameter or is the problem just adding a shade more shoulder bump.
CatShooter
thefitter said:
Where are you measuring the case diameter? Just in front of the extraactor cut, or up by the web.
Also, 0.549" is still smaller that SAAMI - in otherwords, your case head measurement is fine.
Heavy bolt lift is a sign of "stuff" going on - but where and when the lift (or extraction) is heavy is what tells you where the problem is.
If the head/web is expanded "too much" and the sizing die is not able to bring it back enough, then the resistance is at the top of the lift... it is called "click" because it clicks when it breaks free.
If the bolt has resistance from the start of lift, it means that the case is tight in the chamber - usually (but not always) because the case has stretched, and the sizing die is not adjusted to keep the case short enough to chamber easily.
The question is, do you have dificulty closing the bolt on these cases?
If your lift is heavy from the begining, then you need to "nudge" the soulder back a thou or or two, until you can feel some (but not a lot) of resistance.
At 2 thou of head expansion.. you are just getting them broken in
Brians356
Gold $$ Contributor
You didn't say which cartridge, but let's look at 308 Win.
http://www.saami.org/PubResources/CC_Drawings/Rifle/308%20Winchester.pdf
SAAMI Maximum Case drawing shows 0.4701" (tolerance -.008") just ahead of the extractor cut (0.200 inches ahead of the base) so 0.4621" is within spec.
SAAMI Minimum Chamber drawing shows 0.4714" (tolerance +.002") at that location. so 0.4734" is within spec.
0.4734 - 0.4621 = 0.0113".
That implies expansion of eleven thousandths after firing is not unacceptable (minus a thou or two springback.)
http://www.saami.org/PubResources/CC_Drawings/Rifle/308%20Winchester.pdf
SAAMI Maximum Case drawing shows 0.4701" (tolerance -.008") just ahead of the extractor cut (0.200 inches ahead of the base) so 0.4621" is within spec.
SAAMI Minimum Chamber drawing shows 0.4714" (tolerance +.002") at that location. so 0.4734" is within spec.
0.4734 - 0.4621 = 0.0113".
That implies expansion of eleven thousandths after firing is not unacceptable (minus a thou or two springback.)
CatShooter
brians356 said:
He said what cartridge.
thefitter said:
So the cartridge being discussed it the 7mm SAUM, NOT the 308...
brians356 said:
?? ?? ?? why is the discussion shifting to the 308??
bigedp51
CatShooter said:
Because reading fguffey postings can cause brain damage. :
Geees CatShooter I can remember when your mind was sharp as a whip.
(Sorry I put too much sugar on my Corn Flakes this morning and I'm on my fifth cup of coffee) ;D
CatShooter
bigedp51 said:CatShooter said:
Because reading fguffey postings can cause brain damage. :
Geees CatShooter I can remember when your mind was sharp as a whip.
Well... it used to be, but I gave up coffee about 6 weeks ago - feeling better, but I can't find anything.
bigedp51
SIMPLE TRICK FOR MONITORING PRESSURE OF YOUR RIFLE RELOADS
http://www.hodgdonreloading.com/reloading-education/tips-and-tricks/simple-trick-monitoring-pressure-your-rifle-reloads
One of the first rules of handloading is to always follow the approved reload data. The cautious reloader gradually works up to approved maximum loads to ensure his particular gun does not show pressure signs. Generally this is visual observation of the fired shell case head and primer. There is another slick way to check for pressure signs if you are interested.
Using a blade micrometer that measures in ten thousandths (.0001"), new, unfired cases can be gauged before and after firing to determine reasonably accurate maximum loads. Micrometers measuring in thousandths (.001") are insufficiently accurate to perform these measurements, and should not be used. Previously fired cases cannot be used accurately due to various levels of brass hardening. Measurement is taken just ahead of the extractor groove on the case head must be taken at the same place on the case before and after firing. By placing a small mark on the case head – entering the cartridge in the chamber with mark at 12 o’clock – a consistently accurate measurement can be taken with each firing.
Lower pressure rounds, like the .30-30 Winchester, usually yield maximum pressures at .0003"-.0004" expansion. Modern cartridges, like the .223 Remington, will show maximum pressure at .0004"-.0005", while .308 Winchester, .270 Winchester, etc., typically yield .0005"-.0006" expansion at max pressure. Magnums, like the .300 Winchester Magnum, show maximums at .0006â€-.0007†expansion, and should be measured on the belt.
In conjunction with these measurements, case head signs of pressure should be monitored as well. These signs include very flat primers, slightly cratered primers, ejector marks on the case head, and stiff extraction. All these case head signs indicate high pressure, and loads should be reduced until these signs disappear.
As always, start with the beginning load listed, and cautiously work up to the maximum shown for that set of components, using the methods listed herein.
Now the bad news, I read other information that these expansion figures are ball park because base expansion depends on chamber pressure "AND" the hardness of the brass in the base of the cartridge.
And 95% of the cases in my scrap brass bucket below are factory loaded Federal cases with oversized primer pockets after the "FIRST" firing and could not be reloaded.
http://www.hodgdonreloading.com/reloading-education/tips-and-tricks/simple-trick-monitoring-pressure-your-rifle-reloads
One of the first rules of handloading is to always follow the approved reload data. The cautious reloader gradually works up to approved maximum loads to ensure his particular gun does not show pressure signs. Generally this is visual observation of the fired shell case head and primer. There is another slick way to check for pressure signs if you are interested.
Using a blade micrometer that measures in ten thousandths (.0001"), new, unfired cases can be gauged before and after firing to determine reasonably accurate maximum loads. Micrometers measuring in thousandths (.001") are insufficiently accurate to perform these measurements, and should not be used. Previously fired cases cannot be used accurately due to various levels of brass hardening. Measurement is taken just ahead of the extractor groove on the case head must be taken at the same place on the case before and after firing. By placing a small mark on the case head – entering the cartridge in the chamber with mark at 12 o’clock – a consistently accurate measurement can be taken with each firing.
Lower pressure rounds, like the .30-30 Winchester, usually yield maximum pressures at .0003"-.0004" expansion. Modern cartridges, like the .223 Remington, will show maximum pressure at .0004"-.0005", while .308 Winchester, .270 Winchester, etc., typically yield .0005"-.0006" expansion at max pressure. Magnums, like the .300 Winchester Magnum, show maximums at .0006â€-.0007†expansion, and should be measured on the belt.
In conjunction with these measurements, case head signs of pressure should be monitored as well. These signs include very flat primers, slightly cratered primers, ejector marks on the case head, and stiff extraction. All these case head signs indicate high pressure, and loads should be reduced until these signs disappear.
As always, start with the beginning load listed, and cautiously work up to the maximum shown for that set of components, using the methods listed herein.
Now the bad news, I read other information that these expansion figures are ball park because base expansion depends on chamber pressure "AND" the hardness of the brass in the base of the cartridge.
And 95% of the cases in my scrap brass bucket below are factory loaded Federal cases with oversized primer pockets after the "FIRST" firing and could not be reloaded.
Brians356
Gold $$ Contributor
CatShooter said:
Why do you care? You may need your meds adjusted just a tad.
But I'll humor you:
7mm RSAUM:
SAAMI Maximum Case drawing shows 0.5500" (tolerance -.008") just ahead of the extractor cut (0.200 inches ahead of the base) so 0.5420" is within spec.
SAAMI Minimum Chamber drawing shows 0.5510" (tolerance +.002") at that location. so 0.5530" is within spec.
0.5530 - 0.5420 = 0.0110".
That implies expansion of eleven thousandths after firing is not unacceptable (minus a thou or two springback.)
Happy now?The difference between 308 Win and 7mm RSAUM turned out to be a whopping 0.0003". Good thing you saved the OP's life by catching that. ???
CatShooter
brians356 said:
You missed the whole thing....
His unfired case was "New brass = .547"
His fired case was Fired 6x = .549"
That is TWO THOU (0.002"), not 0.011"... so I don't know what thread you are following, but it sure ain't this one.
CatShooter
brians356 said:
<sigh>... no you did not. There are no SAAMI standards for case head expansion.
There are chamber min/max, and case min/max.... those numbers do not have anything to do with acceptable expansion of a case in a chamber, under presure.
That number depends on several variables, which are not defined.
You picked the wrong sourse for your information... on something that you do not understand.
bigedp51
brians356 said:
brians356
CatShooter is the last person in the world I would insult about "meds" and is a straight shooter. The only thing I can fault him for is lubing case "BUT" I have never found fault with the information he posts.
(besides he laughs at my bad jokes)
The only person I contemplate with being "off his meds", and I'm leaning more toward senility is fguffey.
CatShooter has forgotten more than both of us think we know...........and you just said the wrong thing.
Many people post here after putting their tampon in sideways and you have to take it in stride.
Signed
Attilla the Hun.
bigedp51
thefitter said:
brians356
I almost forgot, this is the last posting I would get torqued off in..........................
If the OP doesn't like your answers he tells you to go frack yourself!
(the OP wife puts saltpeter on his Corn Flakes in the morning making him a much calmer person and unable to get laid)
Brians356
Gold $$ Contributor
If you fire a SAAMI minimum cartridge in a SAAMI maximum chamber, the case could indeed expand as much as 0.011".
Is that a likely scenario? No. Is it a distortion of the facts, gleaned from SAAMI specs? No. Does it answer the OP's question, literally construed? It certainly does.
Better take one more. 8)
Is that a likely scenario? No. Is it a distortion of the facts, gleaned from SAAMI specs? No. Does it answer the OP's question, literally construed? It certainly does.
Better take one more. 8)
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