Primers back out of shell! - Page 2

Brian Pfleuger · January 21, 2011, 10:45 AM

Factory loads develop enough pressure to stretch the brass and reseat the primer.

QuickLoad thinks your load is only developing about 33,000 psi. That's a very, very light load in .308.

When a primer is ignited, the flash hole in the case is not large enough to allow all of the gas and pressure to escape instantly from the primer pocket. This causes the primer to push back against the breech face. As the powder begins to burn, the pressure inside the case begins to push the bullet forward and the case backwards. If the pressure is sufficiently high, roughly 30,000psi but dependent on case and chamber "smoothness" somewhat, the brass will stick to the chamber walls and will stretch in the head region (where it's not actually touching the chamber). The only thing stopping that stretch is when it contacts the breech.... where is inevitably reseats the primer.

If the primer is sticking out after firing, you have an indicator of your headspace. Your headspace is AT LEAST .011, and probably a bit more. That is very large and will lead to head separation issues with most brass in not very many full/high pressure loads.

In your instance, my guess is that the pressure is high enough to stick the case but not high enough to stretch it. I want to say that pressure high enough to stick it would stretch it also, but I don't know, that's my best theory.

Your lighter loads using different brass are, well... different. It's likely that the lighter load does stick the case to the chamber, so it slides back and reseats the primer. The primer DOES back out, it's just being reseated.

Primers are virtually always pushed back against the breech when ignited. You can tell because post-firing they will be almost perfectly flush with the case (on normal loads).

F. Guffey · January 21, 2011, 11:13 AM

What does it mean? I could explain, but tomorrow I would have to do it again Or type slower, as with James Taylor when he explains the harm to his engine when he is in a traffic jam, he says "It hurts my motor to go so slow" it hurts my fingers to type so slow. So I filed the response to a draft.

F. Guffey

HiBC · January 21, 2011, 02:13 PM

Get a bushing type case gage from Wilson,Dillon,etc.
Use it to determine you are resizing the case to the proper length.
As peetzakilla said,there is a good chance you are setting the shoulder back with your dies.
The other possibility is you may have a rifle with loose headspace.This canbe checked by a gunsmith with headspace gages.The field gage tells you if the rifle is getting scary,needs fixing.
.011 ,when you get to higher pressure loads,will cause your brass to stretch/thin very quickly.I like .002 in a bolt rifle.
Look in loading manuals to find an explanation with pix of stretch rings,the bent paper clip,etc

steve4102 · January 22, 2011, 02:54 AM

Just bump the charge up and go shootin! It's really just that simple. Your charge is to low, not enough pressure, bump it up, or you can beat your head against the wall trying to find a headspace issue that may not exist. Bump it up!

GP100man · January 22, 2011, 04:02 AM

How bout this , I`ve called a couple of ole time milsurp gurus & this is what I comprehended :

Agreed the load is sorta light/mid range sorta .

The firing pin drives the case forward , primer ignites the charge & it sends the bullet down the barrel .

This load of powder consumes itself to the point it is peaked before the bullet exits the barrel & pressure starts dropping & this particular lot of brass pulls the head of the case .011 from the bolt allowing what remains of the pressure to push the primer out .011.

I was told it was uncommon but not unheard of

you bet !!!

Have I ever heard of a thing, nope !! but I don`t run in the milsurp circuit.

But it took me a couple of days to decide to put it into type for I have no way to prove or disprove this theory .

highvel · January 22, 2011, 08:20 AM

I would think a rough chamber could also be part of this phenomenon.

poline · January 22, 2011, 08:31 AM

HiBC
Senior Member

Join Date: November 13, 2006
(
Posts: 1,828 Get a bushing type case gage from Wilson,Dillon,etc.
Use it to determine you are resizing the case to the proper length.
As peetzakilla said,there is a good chance you are setting the shoulder back with your dies.
The other possibility is you may have a rifle with loose headspace.This can be checked by a gunsmith with headspace gages.The field gage tells you if the rifle is getting scary,needs fixing.
.011 ,when you get to higher pressure loads,will cause your brass to stretch/thin very quickly.I like .002 in a bolt rifle.
Look in loading manuals to find an explanation with pix of stretch rings,the bent paper clip,etc )

I think I recall something about the stretch rings and paper clip in a thread from earlier this year. I will bump up the charge abit and I will reaccess my die and I will use this paper clip thing to give myself some piece of mind. From time to time I will report my findings to the forum.
To all of you on this forum, that give so freely of your time and your advice, I'm so very grateful. THANK YOU, SO VERY, VERY, MUCH!!!!!!!!!

snuffy · January 22, 2011, 01:50 PM

I agree with the excessive headspace caused by oversized brass, coupled with a very low powder charge.

My question would be, WHY? Why such a low powder charge? Open the throttle a bit on those loads. AFTER you solve the problem you obviously have with headspace. Either the rifle has excessive headspace, or you're sizing the brass tOO much. Not addressing the headspace issue WILL result in case-head-separations.

I have a Savage .308 that has excessive headspace. I loaded shells using normal Hornady .308 FL dies. With the shell holder tight against the bottom of the die, I got backed out primers with starting loads of surplus 4895. I then noticed shiny rings on some normal loads with varget and checked them with a RCBS case gauge. There it was, the dreaded internal ring , right opposite the external shiny ring. Caused me to junk over 100 cases!

Solution was to back out the FL die about ½ turn, result was no more case stretching. Another fix would be to take it to a gunsmith to have the barrel turned in a bit. Of course this is only possible with the Savage system of the barrel nut holding the barrel. Most bolt rifles have the barrel held by a shoulder torqued to the receiver.

brickeyee · January 22, 2011, 02:12 PM

If you are reloading for the same rifle you do not need to return the brass back to minimum size, just make it fits back in the chamber.

Complete full length sizing is only needed if the brass will be fired in a different gun of unknown chamber dimensions.

Repeated full length sizing back to minim dimension WILL result in brass stretch with every firing and eventual case head separation.

How many times you can get away with it depends on how much excess head space the gun has and how much you actually force it back in sizing each time.

You will also have to trim brass more often.

misskimo · January 22, 2011, 08:18 PM

Do one thing at a time to rule it out to find the problem

poline · January 23, 2011, 12:05 AM

[ Complete full length sizing is only needed if the brass will be fired in a different gun of unknown chamber dimensions [

The brass in question was range pick up, therefore I full sized it. However it is now fireformed for my rilfe, therefore after useing the paper clip to check for a inter ring I will just neck size it only.

Brian Pfleuger · January 23, 2011, 10:42 AM

If you've got the cash to spare, you should consider getting a Lee Collet neck sizing die and a Redding Body "shoulder bump" die.

That would make your life a lot easier.

The Lee die has got to be the easiest die to use (no lube, no nothing) and it works very, very well, while the Redding body die will allow you to set the shoulder back a very small amount, very consistently. Probably .001 is all you need.

After the case have been fired in your gun, setting the shoulder back .001 will insure perfect headspace and prevent any further stretching and/or head separation.

F. Guffey · January 25, 2011, 03:41 PM

A rough chamber or a chamber with dirt, grit and grime? The most efficient chamber at holding a case it the very smooth chamber, that would be a chamber with a mirror finish WITH a case with the same finish, it does not get better than 100% contact between 2 surfaces as with coefficient of friction, a chamber with machine marks only holds where it touches, the area between the threads reduces contact BUT who has ever heard of a chamber that was cut with a lathe, and grit, dirt and grime will reduce friction by allowing the case to move like it was on rollers, then there is the embed ability of brass, a case that has been embed with hard material could be used to measure skid marks, if skid marks existed in reloading, but with all the talk about case stretch I expect someone to find it any day.

F. Guffey

brickeyee · January 25, 2011, 08:12 PM

Quote:

BUT who has ever heard of a chamber that was cut with a lathe

If a chamber is cut with a reamer it is going to be as smooth as can be had, short of additional polishing.

Single point cutting on a lath leaves a rougher surface than reaming.

poline · January 27, 2011, 02:54 PM

I would not want anyone to not reply to my post, because they thought I was thru. I just have real need to thank all of you that replyed to my thread.
THANK YOU, VERY MUCH!!!!!!

January 21, 2011, 10:45 AM	#26
Brian Pfleuger Moderator Emeritus Join Date: June 25, 2008 Location: Austin, CO Posts: 19,578	Factory loads develop enough pressure to stretch the brass and reseat the primer. QuickLoad thinks your load is only developing about 33,000 psi. That's a very, very light load in .308. When a primer is ignited, the flash hole in the case is not large enough to allow all of the gas and pressure to escape instantly from the primer pocket. This causes the primer to push back against the breech face. As the powder begins to burn, the pressure inside the case begins to push the bullet forward and the case backwards. If the pressure is sufficiently high, roughly 30,000psi but dependent on case and chamber "smoothness" somewhat, the brass will stick to the chamber walls and will stretch in the head region (where it's not actually touching the chamber). The only thing stopping that stretch is when it contacts the breech.... where is inevitably reseats the primer. If the primer is sticking out after firing, you have an indicator of your headspace. Your headspace is AT LEAST .011, and probably a bit more. That is very large and will lead to head separation issues with most brass in not very many full/high pressure loads. In your instance, my guess is that the pressure is high enough to stick the case but not high enough to stretch it. I want to say that pressure high enough to stick it would stretch it also, but I don't know, that's my best theory. Your lighter loads using different brass are, well... different. It's likely that the lighter load does stick the case to the chamber, so it slides back and reseats the primer. The primer DOES back out, it's just being reseated. Primers are virtually always pushed back against the breech when ignited. You can tell because post-firing they will be almost perfectly flush with the case (on normal loads). __________________ Nobody plans to screw up their lives... ...they just don't plan not to. -Andy Stanley

January 22, 2011, 04:02 AM	#30
GP100man Senior Member Join Date: August 1, 2007 Location: Tabor City , NC. Posts: 1,969	How bout this , I`ve called a couple of ole time milsurp gurus & this is what I comprehended : Agreed the load is sorta light/mid range sorta . The firing pin drives the case forward , primer ignites the charge & it sends the bullet down the barrel . This load of powder consumes itself to the point it is peaked before the bullet exits the barrel & pressure starts dropping & this particular lot of brass pulls the head of the case .011 from the bolt allowing what remains of the pressure to push the primer out .011. I was told it was uncommon but not unheard of you bet !!! Have I ever heard of a thing, nope !! but I don`t run in the milsurp circuit. But it took me a couple of days to decide to put it into type for I have no way to prove or disprove this theory . __________________ GP100man

January 22, 2011, 08:20 AM	#31
highvel Senior Member Join Date: January 21, 2010 Location: Powhatan VA Posts: 633	I would think a rough chamber could also be part of this phenomenon. __________________ Do not argue with an idiot. He will drag you down to his level and beat you with experience.--Mark Twain "I have opinions of my own 'strong opinions' but I don't always agree with them."--George Bush

January 22, 2011, 01:50 PM	#33
snuffy Senior Member Join Date: May 20, 2001 Location: Oshkosh wi. Posts: 3,055	I agree with the excessive headspace caused by oversized brass, coupled with a very low powder charge. My question would be, WHY? Why such a low powder charge? Open the throttle a bit on those loads. AFTER you solve the problem you obviously have with headspace. Either the rifle has excessive headspace, or you're sizing the brass tOO much. Not addressing the headspace issue WILL result in case-head-separations. I have a Savage .308 that has excessive headspace. I loaded shells using normal Hornady .308 FL dies. With the shell holder tight against the bottom of the die, I got backed out primers with starting loads of surplus 4895. I then noticed shiny rings on some normal loads with varget and checked them with a RCBS case gauge. There it was, the dreaded internal ring , right opposite the external shiny ring. Caused me to junk over 100 cases! Solution was to back out the FL die about ½ turn, result was no more case stretching. Another fix would be to take it to a gunsmith to have the barrel turned in a bit. Of course this is only possible with the Savage system of the barrel nut holding the barrel. Most bolt rifles have the barrel held by a shoulder torqued to the receiver. __________________ The more people I meet, the more I love my dog They're going to get their butts kicked over there this election. How come people can't spell and use words correctly?

January 22, 2011, 02:12 PM	#34
brickeyee Senior Member Join Date: December 29, 2004 Posts: 3,351	If you are reloading for the same rifle you do not need to return the brass back to minimum size, just make it fits back in the chamber. Complete full length sizing is only needed if the brass will be fired in a different gun of unknown chamber dimensions. Repeated full length sizing back to minim dimension WILL result in brass stretch with every firing and eventual case head separation. How many times you can get away with it depends on how much excess head space the gun has and how much you actually force it back in sizing each time. You will also have to trim brass more often. Last edited by brickeyee; January 25, 2011 at 08:09 PM.

January 21, 2011, 11:13 AM	#27
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	What does it mean? I could explain, but tomorrow I would have to do it again Or type slower, as with James Taylor when he explains the harm to his engine when he is in a traffic jam, he says "It hurts my motor to go so slow" it hurts my fingers to type so slow. So I filed the response to a draft. F. Guffey

January 21, 2011, 02:13 PM	#28
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,289	Get a bushing type case gage from Wilson,Dillon,etc. Use it to determine you are resizing the case to the proper length. As peetzakilla said,there is a good chance you are setting the shoulder back with your dies. The other possibility is you may have a rifle with loose headspace.This canbe checked by a gunsmith with headspace gages.The field gage tells you if the rifle is getting scary,needs fixing. .011 ,when you get to higher pressure loads,will cause your brass to stretch/thin very quickly.I like .002 in a bolt rifle. Look in loading manuals to find an explanation with pix of stretch rings,the bent paper clip,etc

January 22, 2011, 02:54 AM	#29
steve4102 Senior Member Join Date: December 23, 2005 Location: Minnesota Posts: 2,955	Just bump the charge up and go shootin! It's really just that simple. Your charge is to low, not enough pressure, bump it up, or you can beat your head against the wall trying to find a headspace issue that may not exist. Bump it up!

January 22, 2011, 08:31 AM	#32
poline Senior Member Join Date: January 27, 2009 Location: Richmond,Va Posts: 292	HiBC Senior Member Join Date: November 13, 2006 ( Posts: 1,828 Get a bushing type case gage from Wilson,Dillon,etc. Use it to determine you are resizing the case to the proper length. As peetzakilla said,there is a good chance you are setting the shoulder back with your dies. The other possibility is you may have a rifle with loose headspace.This can be checked by a gunsmith with headspace gages.The field gage tells you if the rifle is getting scary,needs fixing. .011 ,when you get to higher pressure loads,will cause your brass to stretch/thin very quickly.I like .002 in a bolt rifle. Look in loading manuals to find an explanation with pix of stretch rings,the bent paper clip,etc ) I think I recall something about the stretch rings and paper clip in a thread from earlier this year. I will bump up the charge abit and I will reaccess my die and I will use this paper clip thing to give myself some piece of mind. From time to time I will report my findings to the forum. To all of you on this forum, that give so freely of your time and your advice, I'm so very grateful. THANK YOU, SO VERY, VERY, MUCH!!!!!!!!!

January 22, 2011, 08:18 PM	#35
misskimo Senior Member Join Date: September 26, 2009 Location: Kotzebue Alaska Posts: 120	Do one thing at a time to rule it out to find the problem

January 23, 2011, 12:05 AM	#36
poline Senior Member Join Date: January 27, 2009 Location: Richmond,Va Posts: 292	Brickeyee [ Complete full length sizing is only needed if the brass will be fired in a different gun of unknown chamber dimensions [ The brass in question was range pick up, therefore I full sized it. However it is now fireformed for my rilfe, therefore after useing the paper clip to check for a inter ring I will just neck size it only.

January 23, 2011, 10:42 AM	#37
Brian Pfleuger Moderator Emeritus Join Date: June 25, 2008 Location: Austin, CO Posts: 19,578	If you've got the cash to spare, you should consider getting a Lee Collet neck sizing die and a Redding Body "shoulder bump" die. That would make your life a lot easier. The Lee die has got to be the easiest die to use (no lube, no nothing) and it works very, very well, while the Redding body die will allow you to set the shoulder back a very small amount, very consistently. Probably .001 is all you need. After the case have been fired in your gun, setting the shoulder back .001 will insure perfect headspace and prevent any further stretching and/or head separation. __________________ Nobody plans to screw up their lives... ...they just don't plan not to. -Andy Stanley

January 25, 2011, 03:41 PM	#38
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	A rough chamber or a chamber with dirt, grit and grime? The most efficient chamber at holding a case it the very smooth chamber, that would be a chamber with a mirror finish WITH a case with the same finish, it does not get better than 100% contact between 2 surfaces as with coefficient of friction, a chamber with machine marks only holds where it touches, the area between the threads reduces contact BUT who has ever heard of a chamber that was cut with a lathe, and grit, dirt and grime will reduce friction by allowing the case to move like it was on rollers, then there is the embed ability of brass, a case that has been embed with hard material could be used to measure skid marks, if skid marks existed in reloading, but with all the talk about case stretch I expect someone to find it any day. F. Guffey

January 27, 2011, 02:54 PM	#40
poline Senior Member Join Date: January 27, 2009 Location: Richmond,Va Posts: 292	I would not want anyone to not reply to my post, because they thought I was thru. I just have real need to thank all of you that replyed to my thread. THANK YOU, VERY MUCH!!!!!!