I had a case head separate yesterday while shooting. Round sounded fine and was part of .5 moa group, but when I pulled the empty out it had a black ring which turned out to be a crack around 3/4 of the base of the case. It was a .308, winchester brass, on the 3rd. firing. Haven't been really loading them hot, 44.5 gr. Varget under 175 SMK. I checked all of my other brass that had been fired and found a few more with a ring developing inside the case. The question is this, the ring is only on half the diameter of the case and you can see a slight bulge on the outside of the cases that corresponds with the ring. Is this normal or should the ring be all the way around the base?
.308 case head separation
- Thread starter Dusty
- Start date
Re: .308 case head separation
Do you have your sizing die properly adjusted? Same thing was happening to me until i started using my Rcbs precision mic, and measured my fired brass.I was over sizing my brass way too much.
Do you have your sizing die properly adjusted? Same thing was happening to me until i started using my Rcbs precision mic, and measured my fired brass.I was over sizing my brass way too much.
Re: .308 case head separation
There is no "normal" case head seperation. If there is a failure in the bottom 1/4th of the case it just falls into that category.
Was the brass new when you bought it or "once fired"? If you only had 3 handloading cycles on it, you need to check your die / chamber relation setup. Because something is wrong. I full length size everything. I have gotten over 15 load cycles on 308 before. They were medium loads and the brass was annealed at least once. But having the die set right with the chamber is a LOT of making brass last.
There is no "normal" case head seperation. If there is a failure in the bottom 1/4th of the case it just falls into that category.
Was the brass new when you bought it or "once fired"? If you only had 3 handloading cycles on it, you need to check your die / chamber relation setup. Because something is wrong. I full length size everything. I have gotten over 15 load cycles on 308 before. They were medium loads and the brass was annealed at least once. But having the die set right with the chamber is a LOT of making brass last.
Re: .308 case head separation
Just an FYI, that 44.5gr of varget is 0.5 gr under max load of 45gr(compressed) from Hodgdon and 1 grain OVER the max listed of 43.5gr in the Sierra manual. It is a rather stout load.
Are you having any other pressure signs? Running that close to max load, any measurement error can put you into split case territory (at best).
I know every gun is different, and your gun may be doing fine with the load and showing no pressure signs(which aren't all that accurate), but I tend to trust Sierra with the incredible detail of their testing arrangements.
I use 42gr of Varget under my 175 SMKs (when I use Varget). My guns seem to like that but they also seem to like Rel-15 better
Just my 0.02,
madd0c
Just an FYI, that 44.5gr of varget is 0.5 gr under max load of 45gr(compressed) from Hodgdon and 1 grain OVER the max listed of 43.5gr in the Sierra manual. It is a rather stout load.
Are you having any other pressure signs? Running that close to max load, any measurement error can put you into split case territory (at best).
I know every gun is different, and your gun may be doing fine with the load and showing no pressure signs(which aren't all that accurate), but I tend to trust Sierra with the incredible detail of their testing arrangements.
I use 42gr of Varget under my 175 SMKs (when I use Varget). My guns seem to like that but they also seem to like Rel-15 better
Just my 0.02,
madd0c
Re: .308 case head separation
I readjusted my sizing die. my fired brass measures .470 .200 up from the rim. I was sizing it back to .466. I readjusted it to size it back to .468. Do you think this it too much, too? I don't have a mic, but I am using a dial caliper to take measurements. As far as pressure signs, I have some semi flattened primers and large craters around the firing pin. It is a rem 700 5r and the bolt face it pretty rough, but I here that is normal for a 700 now. What about only half of the base is separating and not the other half? Would this indicate the bolt is not inline with the barrel?
I readjusted my sizing die. my fired brass measures .470 .200 up from the rim. I was sizing it back to .466. I readjusted it to size it back to .468. Do you think this it too much, too? I don't have a mic, but I am using a dial caliper to take measurements. As far as pressure signs, I have some semi flattened primers and large craters around the firing pin. It is a rem 700 5r and the bolt face it pretty rough, but I here that is normal for a 700 now. What about only half of the base is separating and not the other half? Would this indicate the bolt is not inline with the barrel?
Re: .308 case head separation
An egg shaped chamber! WTF?
How many thousandths of an inch are we talking when you say egg shaped?
An egg shaped chamber! WTF?
How many thousandths of an inch are we talking when you say egg shaped?
Re: .308 case head separation
Have a barrel custom chambered and you will know what I'm talking about.
A few years back, I was looking to buy a Rem Tac in 308. After looking at 4 of them in differant shops in differant cities, none had a straight chamber. You could look down to the chamber and see were the rifling started in the throat and see that the chamber was off to one side more than the other. I could see maybe one but not 4 in all differant cities. To me that means most are that way. I even looked at a PSS a few months back and it was the same way.
Now, with Rem. having a bad chamber and improper set-up of the dies, you are going to have a case seperate sooner on the chamber that is bad before a chamber that is good.
Have a barrel custom chambered and you will know what I'm talking about.
A few years back, I was looking to buy a Rem Tac in 308. After looking at 4 of them in differant shops in differant cities, none had a straight chamber. You could look down to the chamber and see were the rifling started in the throat and see that the chamber was off to one side more than the other. I could see maybe one but not 4 in all differant cities. To me that means most are that way. I even looked at a PSS a few months back and it was the same way.
Now, with Rem. having a bad chamber and improper set-up of the dies, you are going to have a case seperate sooner on the chamber that is bad before a chamber that is good.
Re: .308 case head separation
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dusty</div><div class="ubbcode-body">I readjusted my sizing die. my fired brass measures .470 .200 up from the rim. I was sizing it back to .466. I readjusted it to size it back to .468. </div></div>
I think you are misunderstanding where and how to measure. To make accurate and measurable changes to your brass you need an instrument to do it with. Most people that measure their cartridges to set the headspace use a guage like a Hornady or Stoney Point.
But there is another way. Here's something I wrote up on it a few years ago.
Adjusting a Full Length Sizer Die for a bolt action rifle.
PLEASE… Read through this a couple of times before attempting to do it. If any of this data doesn’t make sense to you STOP…! If there is any part of this you don’t understand… STOP…! The author is making observances about what he has done with his own equipment. Your equipment, dies, shell holders, rifle, cartridge brass and other components may be different. I can almost promise they are. If you do this, you are doing it on your own accord. I accept NO legal implication or obligation. As someone shooting wildcat cartridges I have some experience in changing factory settings ON MY EQUIPMENT. I have even made my own dies in the past. I caution against “beginners” doing this procedure. Wait until you understand the physics of what you are doing a bit more.
For years I struggled with neck sizing for my first benchrest rifle. Size “X” number times then bump the shoulder with a body die. I never had the comfort I was looking for when it came time to cycle the bolt.
While I was complaining at the “Firearms Industry Super Shoot” one year, a friend took me aside and told me that he would come back later that night after supper and help me with the problem. He said to leave everything as it was at the time. Since he had set several world records in the sport I did as he requested.
When he returned, he told me to get my brass and remove the firing pin from the bolt. He asked if I had a full length sizing die and I said yes. Since I was using a bushing die for the neck sizer I just had to pop the bushing out and use it in the F/L die.
He explained that the shoulder of the brass was pushing against the shoulder of the chamber and making it hard to chamber a round and remove it later. This I understood. But I thought the chamber would hold it close to the same length. WRONG… It doesn’t work like that. The case will keep stretching until it fills the chamber and the bolt handle doesn’t want to lever it loose. (I have since seen photos of a very high dollar rifle with the bolt handle knocked off because someone thought he wanted to neck size only.) But I’m getting off track…
Screw the sizing die in the top of the press as the instructions say. Then back it out 1 full turn. Lube a few cases properly. (I use Imperial Sizing wax. A little bit on a finger tip will lube 3 or 4 cases.) You can use 1 or 2 cases to get things close. But for the final settings you need to use a fresh case each time. Cycle a case through the die and press. Then try it in the chamber. (Having removed the firing pin, there is no trigger reset or spring pressure to give false “feelings”.) You want to screw the die down in 1/16th of a turn increments. That works out to roughly .0045”, (four and a half thousands of an inch.) As you approach the shell holder you will eventually find a spot where the bolt handle easily moves forward all the way and starts over on its own weight. This is what you’re looking for. You want the bolt handle to just start down on its own weight. I usually adjust mine for half way down. It makes it easier to cycle the bolt without disturbing the sand bags and changing your aiming position.
When you have found this spot, try a fresh case and see if it works the same. Usually after using the same piece of brass for several trials, a fresh piece will have more “spring” to it and you’ll have to give it a little more squeeze to make it the same. Remember, when you are sizing your brass, most people cycle each piece of brass only one time. It just makes sense to me to do it the same way.
After doing this another accomplished rifle smith showed me a little collar he made from an old barrel stub and a chambering reamer. (This was before Stoney Point started making their adapter for dial calipers.) By slipping this over the case neck and setting it against the shoulder you can reliably measure the amount you are pushing the shoulder back each time you pull the handle. By doing it the way I have outlined in the previous paragraph most of my brass is being pushed back between .0015 and .003”. (The number of times the brass has been fired and whether or not it has been annealed will have a bearing to an extent on how hard you will have to size the brass.) This is what a lot of rifle smiths suggest as a benchmark for “bumping” the shoulder back. This way the brass isn’t being “over worked”.
NOTE : Some dies will hit the shell holder before they ever get down low enough for your chamber. I have had this problem with about half of the dies I have set up like this. Remove the decapping pin and expander ball assembly. I set the dies up in a toolmaker’s “V Block” and use a surface grinder to remove approximately .010” from the length of the bottom of the die. Most dies have a very large radius ground in the first part of the inside diameter. This part is not making contact with the cartridge brass anyway. But it is used as a legal stop gap for the manufacturer. By using this, the maker can say he has made the die to SAAMI specs. But this is not what your rifle wants. After you have the die altered and set up properly make yourself a note and put it in place with a rubber band around this die. Keep it with the die at all times. Make it say what rifle the die is for and what alterations have been made to it. Also record what temperature it is at the time of the settings. If you load in an 85 degree house and shoot the ammo at 12 degrees in a blinding snowstorm, there will be a difference. The difference in temperature will make the chamber and die difference be an additional .001” or so.
I have also started using shims cut to fit the 7/8 - 14 size of the die in the press. This way you can hold the movements down to as close to .001. MSC Supply carries these shims in assortments as well as in packs of all one thickness. Brownell’s and Sinclair’s also carry them. But the price mark up is substantial if you are getting several packs of shims.
If I’m working that close I also use a “Crow’s foot” wrench with an extension and a torque wrench to keep the settings all the same. Yes, it can make a difference when working close.
Good luck with your loading. I hope you set some records yourself.
vwj: 20-DEC-1996 rev. 4, 2-NOV-2009
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dusty</div><div class="ubbcode-body">I readjusted my sizing die. my fired brass measures .470 .200 up from the rim. I was sizing it back to .466. I readjusted it to size it back to .468. </div></div>
I think you are misunderstanding where and how to measure. To make accurate and measurable changes to your brass you need an instrument to do it with. Most people that measure their cartridges to set the headspace use a guage like a Hornady or Stoney Point.
But there is another way. Here's something I wrote up on it a few years ago.
Adjusting a Full Length Sizer Die for a bolt action rifle.
PLEASE… Read through this a couple of times before attempting to do it. If any of this data doesn’t make sense to you STOP…! If there is any part of this you don’t understand… STOP…! The author is making observances about what he has done with his own equipment. Your equipment, dies, shell holders, rifle, cartridge brass and other components may be different. I can almost promise they are. If you do this, you are doing it on your own accord. I accept NO legal implication or obligation. As someone shooting wildcat cartridges I have some experience in changing factory settings ON MY EQUIPMENT. I have even made my own dies in the past. I caution against “beginners” doing this procedure. Wait until you understand the physics of what you are doing a bit more.
For years I struggled with neck sizing for my first benchrest rifle. Size “X” number times then bump the shoulder with a body die. I never had the comfort I was looking for when it came time to cycle the bolt.
While I was complaining at the “Firearms Industry Super Shoot” one year, a friend took me aside and told me that he would come back later that night after supper and help me with the problem. He said to leave everything as it was at the time. Since he had set several world records in the sport I did as he requested.
When he returned, he told me to get my brass and remove the firing pin from the bolt. He asked if I had a full length sizing die and I said yes. Since I was using a bushing die for the neck sizer I just had to pop the bushing out and use it in the F/L die.
He explained that the shoulder of the brass was pushing against the shoulder of the chamber and making it hard to chamber a round and remove it later. This I understood. But I thought the chamber would hold it close to the same length. WRONG… It doesn’t work like that. The case will keep stretching until it fills the chamber and the bolt handle doesn’t want to lever it loose. (I have since seen photos of a very high dollar rifle with the bolt handle knocked off because someone thought he wanted to neck size only.) But I’m getting off track…
Screw the sizing die in the top of the press as the instructions say. Then back it out 1 full turn. Lube a few cases properly. (I use Imperial Sizing wax. A little bit on a finger tip will lube 3 or 4 cases.) You can use 1 or 2 cases to get things close. But for the final settings you need to use a fresh case each time. Cycle a case through the die and press. Then try it in the chamber. (Having removed the firing pin, there is no trigger reset or spring pressure to give false “feelings”.) You want to screw the die down in 1/16th of a turn increments. That works out to roughly .0045”, (four and a half thousands of an inch.) As you approach the shell holder you will eventually find a spot where the bolt handle easily moves forward all the way and starts over on its own weight. This is what you’re looking for. You want the bolt handle to just start down on its own weight. I usually adjust mine for half way down. It makes it easier to cycle the bolt without disturbing the sand bags and changing your aiming position.
When you have found this spot, try a fresh case and see if it works the same. Usually after using the same piece of brass for several trials, a fresh piece will have more “spring” to it and you’ll have to give it a little more squeeze to make it the same. Remember, when you are sizing your brass, most people cycle each piece of brass only one time. It just makes sense to me to do it the same way.
After doing this another accomplished rifle smith showed me a little collar he made from an old barrel stub and a chambering reamer. (This was before Stoney Point started making their adapter for dial calipers.) By slipping this over the case neck and setting it against the shoulder you can reliably measure the amount you are pushing the shoulder back each time you pull the handle. By doing it the way I have outlined in the previous paragraph most of my brass is being pushed back between .0015 and .003”. (The number of times the brass has been fired and whether or not it has been annealed will have a bearing to an extent on how hard you will have to size the brass.) This is what a lot of rifle smiths suggest as a benchmark for “bumping” the shoulder back. This way the brass isn’t being “over worked”.
NOTE : Some dies will hit the shell holder before they ever get down low enough for your chamber. I have had this problem with about half of the dies I have set up like this. Remove the decapping pin and expander ball assembly. I set the dies up in a toolmaker’s “V Block” and use a surface grinder to remove approximately .010” from the length of the bottom of the die. Most dies have a very large radius ground in the first part of the inside diameter. This part is not making contact with the cartridge brass anyway. But it is used as a legal stop gap for the manufacturer. By using this, the maker can say he has made the die to SAAMI specs. But this is not what your rifle wants. After you have the die altered and set up properly make yourself a note and put it in place with a rubber band around this die. Keep it with the die at all times. Make it say what rifle the die is for and what alterations have been made to it. Also record what temperature it is at the time of the settings. If you load in an 85 degree house and shoot the ammo at 12 degrees in a blinding snowstorm, there will be a difference. The difference in temperature will make the chamber and die difference be an additional .001” or so.
I have also started using shims cut to fit the 7/8 - 14 size of the die in the press. This way you can hold the movements down to as close to .001. MSC Supply carries these shims in assortments as well as in packs of all one thickness. Brownell’s and Sinclair’s also carry them. But the price mark up is substantial if you are getting several packs of shims.
If I’m working that close I also use a “Crow’s foot” wrench with an extension and a torque wrench to keep the settings all the same. Yes, it can make a difference when working close.
Good luck with your loading. I hope you set some records yourself.
vwj: 20-DEC-1996 rev. 4, 2-NOV-2009
Re: .308 case head separation
Excellent advice above.
The best advice I ever received concerning dies was to toss the instructions that came in the box. Although I've been called a fool for doing so, I still recommend it.
Excellent advice above.
The best advice I ever received concerning dies was to toss the instructions that came in the box. Although I've been called a fool for doing so, I still recommend it.
Re: .308 case head separation
"I readjusted my sizing die. my fired brass measures .470 .200 up from the rim. I was sizing it back to .466. I readjusted it to size it back to .468. Do you think this it too much, too?"
The only thing we need be concerned about "adjusting" an FL sizer for is head space, aka shoulder location. Both your "flattened" primers and head seperations are results of setting the shoulders back too far.
"What about only half of the base is separating and not the other half? Would this indicate the bolt is not inline with the barrel?"
The cases are holding together where the metal is a bit thicker than where it pulls apart.
"I readjusted my sizing die. my fired brass measures .470 .200 up from the rim. I was sizing it back to .466. I readjusted it to size it back to .468. Do you think this it too much, too?"
The only thing we need be concerned about "adjusting" an FL sizer for is head space, aka shoulder location. Both your "flattened" primers and head seperations are results of setting the shoulders back too far.
"What about only half of the base is separating and not the other half? Would this indicate the bolt is not inline with the barrel?"
The cases are holding together where the metal is a bit thicker than where it pulls apart.
Re: .308 case head separation
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The cases are holding together where the metal is a bit thicker than where it pulls apart.</div></div>
Or the bolt face isn't square to the chamber...or a combination of both.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The cases are holding together where the metal is a bit thicker than where it pulls apart.</div></div>
Or the bolt face isn't square to the chamber...or a combination of both.
Re: .308 case head separation
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Victor N TN</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dusty</div><div class="ubbcode-body">I readjusted my sizing die. my fired brass measures .470 .200 up from the rim. I was sizing it back to .466. I readjusted it to size it back to .468. </div></div>
I think you are misunderstanding where and how to measure. To make accurate and measurable changes to your brass you need an instrument to do it with. Most people that measure their cartridges to set the headspace use a guage like a Hornady or Stoney Point.
But there is another way. Here's something I wrote up on it a few years ago.
Adjusting a Full Length Sizer Die for a bolt action rifle.
PLEASE… Read through this a couple of times before attempting to do it. If any of this data doesn’t make sense to you STOP…! If there is any part of this you don’t understand… STOP…! The author is making observances about what he has done with his own equipment. Your equipment, dies, shell holders, rifle, cartridge brass and other components may be different. I can almost promise they are. If you do this, you are doing it on your own accord. I accept NO legal implication or obligation. As someone shooting wildcat cartridges I have some experience in changing factory settings ON MY EQUIPMENT. I have even made my own dies in the past. I caution against “beginners” doing this procedure. Wait until you understand the physics of what you are doing a bit more.
For years I struggled with neck sizing for my first benchrest rifle. Size “X” number times then bump the shoulder with a body die. I never had the comfort I was looking for when it came time to cycle the bolt.
While I was complaining at the “Firearms Industry Super Shoot” one year, a friend took me aside and told me that he would come back later that night after supper and help me with the problem. He said to leave everything as it was at the time. Since he had set several world records in the sport I did as he requested.
When he returned, he told me to get my brass and remove the firing pin from the bolt. He asked if I had a full length sizing die and I said yes. Since I was using a bushing die for the neck sizer I just had to pop the bushing out and use it in the F/L die.
He explained that the shoulder of the brass was pushing against the shoulder of the chamber and making it hard to chamber a round and remove it later. This I understood. But I thought the chamber would hold it close to the same length. WRONG… It doesn’t work like that. The case will keep stretching until it fills the chamber and the bolt handle doesn’t want to lever it loose. (I have since seen photos of a very high dollar rifle with the bolt handle knocked off because someone thought he wanted to neck size only.) But I’m getting off track…
Screw the sizing die in the top of the press as the instructions say. Then back it out 1 full turn. Lube a few cases properly. (I use Imperial Sizing wax. A little bit on a finger tip will lube 3 or 4 cases.) You can use 1 or 2 cases to get things close. But for the final settings you need to use a fresh case each time. Cycle a case through the die and press. Then try it in the chamber. (Having removed the firing pin, there is no trigger reset or spring pressure to give false “feelings”.) You want to screw the die down in 1/16th of a turn increments. That works out to roughly .0045”, (four and a half thousands of an inch.) As you approach the shell holder you will eventually find a spot where the bolt handle easily moves forward all the way and starts over on its own weight. This is what you’re looking for. You want the bolt handle to just start down on its own weight. I usually adjust mine for half way down. It makes it easier to cycle the bolt without disturbing the sand bags and changing your aiming position.
When you have found this spot, try a fresh case and see if it works the same. Usually after using the same piece of brass for several trials, a fresh piece will have more “spring” to it and you’ll have to give it a little more squeeze to make it the same. Remember, when you are sizing your brass, most people cycle each piece of brass only one time. It just makes sense to me to do it the same way.
After doing this another accomplished rifle smith showed me a little collar he made from an old barrel stub and a chambering reamer. (This was before Stoney Point started making their adapter for dial calipers.) By slipping this over the case neck and setting it against the shoulder you can reliably measure the amount you are pushing the shoulder back each time you pull the handle. By doing it the way I have outlined in the previous paragraph most of my brass is being pushed back between .0015 and .003”. (The number of times the brass has been fired and whether or not it has been annealed will have a bearing to an extent on how hard you will have to size the brass.) This is what a lot of rifle smiths suggest as a benchmark for “bumping” the shoulder back. This way the brass isn’t being “over worked”.
NOTE : Some dies will hit the shell holder before they ever get down low enough for your chamber. I have had this problem with about half of the dies I have set up like this. Remove the decapping pin and expander ball assembly. I set the dies up in a toolmaker’s “V Block” and use a surface grinder to remove approximately .010” from the length of the bottom of the die. Most dies have a very large radius ground in the first part of the inside diameter. This part is not making contact with the cartridge brass anyway. But it is used as a legal stop gap for the manufacturer. By using this, the maker can say he has made the die to SAAMI specs. But this is not what your rifle wants. After you have the die altered and set up properly make yourself a note and put it in place with a rubber band around this die. Keep it with the die at all times. Make it say what rifle the die is for and what alterations have been made to it. Also record what temperature it is at the time of the settings. If you load in an 85 degree house and shoot the ammo at 12 degrees in a blinding snowstorm, there will be a difference. The difference in temperature will make the chamber and die difference be an additional .001” or so.
I have also started using shims cut to fit the 7/8 - 14 size of the die in the press. This way you can hold the movements down to as close to .001. MSC Supply carries these shims in assortments as well as in packs of all one thickness. Brownell’s and Sinclair’s also carry them. But the price mark up is substantial if you are getting several packs of shims.
If I’m working that close I also use a “Crow’s foot” wrench with an extension and a torque wrench to keep the settings all the same. Yes, it can make a difference when working close.
Good luck with your loading. I hope you set some records yourself.
I see what you are saying, I was just stating that when I readjusted the dies for proper set back of the shoulder, The area just above the base wasn't getting reduced near as much either. I don't have a stoney point or any specific tool to do the measurement with, but I got to thinking about the "die" that I use on my gracey trimmer for trimming .308 casing. It is cut with a reamer and gauges off the case shoulder, so couldn't I use it with a caliper to measure setback, like you where talking about with the section of bbl. reamed out as a guage?
BTW that is a great write up you did.
vwj: 20-DEC-1996 rev. 4, 2-NOV-2009
</div></div>
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Victor N TN</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dusty</div><div class="ubbcode-body">I readjusted my sizing die. my fired brass measures .470 .200 up from the rim. I was sizing it back to .466. I readjusted it to size it back to .468. </div></div>
I think you are misunderstanding where and how to measure. To make accurate and measurable changes to your brass you need an instrument to do it with. Most people that measure their cartridges to set the headspace use a guage like a Hornady or Stoney Point.
But there is another way. Here's something I wrote up on it a few years ago.
Adjusting a Full Length Sizer Die for a bolt action rifle.
PLEASE… Read through this a couple of times before attempting to do it. If any of this data doesn’t make sense to you STOP…! If there is any part of this you don’t understand… STOP…! The author is making observances about what he has done with his own equipment. Your equipment, dies, shell holders, rifle, cartridge brass and other components may be different. I can almost promise they are. If you do this, you are doing it on your own accord. I accept NO legal implication or obligation. As someone shooting wildcat cartridges I have some experience in changing factory settings ON MY EQUIPMENT. I have even made my own dies in the past. I caution against “beginners” doing this procedure. Wait until you understand the physics of what you are doing a bit more.
For years I struggled with neck sizing for my first benchrest rifle. Size “X” number times then bump the shoulder with a body die. I never had the comfort I was looking for when it came time to cycle the bolt.
While I was complaining at the “Firearms Industry Super Shoot” one year, a friend took me aside and told me that he would come back later that night after supper and help me with the problem. He said to leave everything as it was at the time. Since he had set several world records in the sport I did as he requested.
When he returned, he told me to get my brass and remove the firing pin from the bolt. He asked if I had a full length sizing die and I said yes. Since I was using a bushing die for the neck sizer I just had to pop the bushing out and use it in the F/L die.
He explained that the shoulder of the brass was pushing against the shoulder of the chamber and making it hard to chamber a round and remove it later. This I understood. But I thought the chamber would hold it close to the same length. WRONG… It doesn’t work like that. The case will keep stretching until it fills the chamber and the bolt handle doesn’t want to lever it loose. (I have since seen photos of a very high dollar rifle with the bolt handle knocked off because someone thought he wanted to neck size only.) But I’m getting off track…
Screw the sizing die in the top of the press as the instructions say. Then back it out 1 full turn. Lube a few cases properly. (I use Imperial Sizing wax. A little bit on a finger tip will lube 3 or 4 cases.) You can use 1 or 2 cases to get things close. But for the final settings you need to use a fresh case each time. Cycle a case through the die and press. Then try it in the chamber. (Having removed the firing pin, there is no trigger reset or spring pressure to give false “feelings”.) You want to screw the die down in 1/16th of a turn increments. That works out to roughly .0045”, (four and a half thousands of an inch.) As you approach the shell holder you will eventually find a spot where the bolt handle easily moves forward all the way and starts over on its own weight. This is what you’re looking for. You want the bolt handle to just start down on its own weight. I usually adjust mine for half way down. It makes it easier to cycle the bolt without disturbing the sand bags and changing your aiming position.
When you have found this spot, try a fresh case and see if it works the same. Usually after using the same piece of brass for several trials, a fresh piece will have more “spring” to it and you’ll have to give it a little more squeeze to make it the same. Remember, when you are sizing your brass, most people cycle each piece of brass only one time. It just makes sense to me to do it the same way.
After doing this another accomplished rifle smith showed me a little collar he made from an old barrel stub and a chambering reamer. (This was before Stoney Point started making their adapter for dial calipers.) By slipping this over the case neck and setting it against the shoulder you can reliably measure the amount you are pushing the shoulder back each time you pull the handle. By doing it the way I have outlined in the previous paragraph most of my brass is being pushed back between .0015 and .003”. (The number of times the brass has been fired and whether or not it has been annealed will have a bearing to an extent on how hard you will have to size the brass.) This is what a lot of rifle smiths suggest as a benchmark for “bumping” the shoulder back. This way the brass isn’t being “over worked”.
NOTE : Some dies will hit the shell holder before they ever get down low enough for your chamber. I have had this problem with about half of the dies I have set up like this. Remove the decapping pin and expander ball assembly. I set the dies up in a toolmaker’s “V Block” and use a surface grinder to remove approximately .010” from the length of the bottom of the die. Most dies have a very large radius ground in the first part of the inside diameter. This part is not making contact with the cartridge brass anyway. But it is used as a legal stop gap for the manufacturer. By using this, the maker can say he has made the die to SAAMI specs. But this is not what your rifle wants. After you have the die altered and set up properly make yourself a note and put it in place with a rubber band around this die. Keep it with the die at all times. Make it say what rifle the die is for and what alterations have been made to it. Also record what temperature it is at the time of the settings. If you load in an 85 degree house and shoot the ammo at 12 degrees in a blinding snowstorm, there will be a difference. The difference in temperature will make the chamber and die difference be an additional .001” or so.
I have also started using shims cut to fit the 7/8 - 14 size of the die in the press. This way you can hold the movements down to as close to .001. MSC Supply carries these shims in assortments as well as in packs of all one thickness. Brownell’s and Sinclair’s also carry them. But the price mark up is substantial if you are getting several packs of shims.
If I’m working that close I also use a “Crow’s foot” wrench with an extension and a torque wrench to keep the settings all the same. Yes, it can make a difference when working close.
Good luck with your loading. I hope you set some records yourself.
I see what you are saying, I was just stating that when I readjusted the dies for proper set back of the shoulder, The area just above the base wasn't getting reduced near as much either. I don't have a stoney point or any specific tool to do the measurement with, but I got to thinking about the "die" that I use on my gracey trimmer for trimming .308 casing. It is cut with a reamer and gauges off the case shoulder, so couldn't I use it with a caliper to measure setback, like you where talking about with the section of bbl. reamed out as a guage?
BTW that is a great write up you did.
vwj: 20-DEC-1996 rev. 4, 2-NOV-2009
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Re: .308 case head separation
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 81sfo</div><div class="ubbcode-body">Do you have your sizing die properly adjusted? Same thing was happening to me until i started using my Rcbs precision mic, and measured my fired brass.I was over sizing my brass way too much. </div></div>
+1
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 81sfo</div><div class="ubbcode-body">Do you have your sizing die properly adjusted? Same thing was happening to me until i started using my Rcbs precision mic, and measured my fired brass.I was over sizing my brass way too much. </div></div>
+1
