When I see/read a post by Mr Guffey, this picture always pops into my head
Insulting him doesn't work. He just keeps posting.
Shoulder Bumping & Neck Sizing
- Thread starter Butte Sink
- Start date
Insulting him doesn't work. He just keeps posting.
When I see/read a post by Mr Guffey, this picture always pops into my head
Did Corey leave any children?
I believe the highlighted statement to be true. What I can't seem to comprehend and need help understanding is how a case can ever grow longer than the chamber it was fired in and extracted from. Can someone explain why after a few firings the cases have stretched to the point that the bolt will not close because they are now to long - not to fat but to long? Seems impossible to end up with extra length beyond zero case head to bolt clearance but I've measured approximately a 0.0025 inch difference between once fired and thrice fired cases. Does this always occur? - or is there something that can be done to mitigate this phenomenon so that neck sizing only is all that is ever required.
Ken
kvd, as you can see there is more going on than most of the members can keep up with. As I have said before; this stuff does not drive me to the curb. I can load a case, chamber it and then fire it for the first time and know it will not chamber 'IF' I am able to remove it from the chamber" Rational; Hitting a case with a heavy load can remove the memory of the case, meaning the case can not remember what it was before I pulled the trigger.
Reloaders have claimed they can fire a case once and then neck size it 4 time and then start over by full length sizing; and I ask: How can that be, the case has been fired 5 times. When I fire a case 5 times it work hardens, meaning the cases ability to resist sizing increases ever time it is fired. And there are members in the claims department that claim they have fired a case 45+ times, after examining the case after 45 firings he found no measurable evidence the case had been fired; and I ask him what the case weighed when he started and what did the case weight after 45 firings, I did not get an answer so I assumed he did not understand the question.
For me there is no one answer, I have a few long chambers, I form first then fire, I have go-gage length chambers, most of my go-gage length chambers tolerate fire forming; believe it or not, the shoulder of my cases never make it to the shoulder of the chamber. If my cases took off for the front of the chamber and stopped when the case shoulder contacted the shoulder of the chamber?? That would be a bad thing.
Back to the top:
F. Guffey
F. Guffey,
Despite the fact that you seem to be much maligned on this forum for some of your ideas, I can appreciate your comments. Thanks for responding.
It seems to me that a few thousandths clearance between the case neck and the chamber neck coupled with a few thousandths clearance between the case shoulder and the chamber shoulder would cause the cartridge to rest in the chamber at an angle due to the heavy back end - especially with generous head clearance. Shouldn't the precision reloader being doing all that is possible to align the bullet in the cartridge and subsequently the cartridge with the bore? Loose tolerances seem contrary to this goal.
Ken
Despite the fact that you seem to be much maligned on this forum for some of your ideas, I can appreciate your comments. Thanks for responding.
It seems to me that a few thousandths clearance between the case neck and the chamber neck coupled with a few thousandths clearance between the case shoulder and the chamber shoulder would cause the cartridge to rest in the chamber at an angle due to the heavy back end - especially with generous head clearance. Shouldn't the precision reloader being doing all that is possible to align the bullet in the cartridge and subsequently the cartridge with the bore? Loose tolerances seem contrary to this goal.
Ken
kvd
When the case is fired it expands like a balloon and that stretches the brass some. Yes the brass can spring back some but not 100%. So it does retain some of the stretch from being fired especially radial stretch, that is stretch on the diameters.
When the stretched case is resized the case is compressed by the die. The die and the shell holder squeeze against the case in every direction except one. That one direction is from the case mouth direction. Since the brass cannot really be compressed when resized it will move in the direction that it is not constrained and that is out the top of the die.
To verify all this is true take new brass and trim it all to the same length.
Then fire it
Then measure it and you will find that it is shorter
Then FL resize it and it will grow longer.
Each firing cycle and resizing cycle contributes to the growth of the case lengths.
When you have a maximum die that produces sized cases that are a very close size match to a minimum chamber the brass stretching is minimized. When stretching is reduced so is case lengthening.
The case stretching phenomena is the result in the mismatch of the case size and the chamber before the round is fired.
When the case is fired it expands like a balloon and that stretches the brass some. Yes the brass can spring back some but not 100%. So it does retain some of the stretch from being fired especially radial stretch, that is stretch on the diameters.
When the stretched case is resized the case is compressed by the die. The die and the shell holder squeeze against the case in every direction except one. That one direction is from the case mouth direction. Since the brass cannot really be compressed when resized it will move in the direction that it is not constrained and that is out the top of the die.
To verify all this is true take new brass and trim it all to the same length.
Then fire it
Then measure it and you will find that it is shorter
Then FL resize it and it will grow longer.
Each firing cycle and resizing cycle contributes to the growth of the case lengths.
When you have a maximum die that produces sized cases that are a very close size match to a minimum chamber the brass stretching is minimized. When stretching is reduced so is case lengthening.
The case stretching phenomena is the result in the mismatch of the case size and the chamber before the round is fired.
swd
Silver $$ Contributor
Whenever I see an F Guffy post it makes me think of Francis Duffy, one of the condemned guys in the Clint Eastwood spaghetti western Hang em High. He's the one that just rambles on and on. Finally one of other condemned when they ask if he has any last words says "just tell him to shut up and get it over with". Anyways that's my visual every time I see one of his posts.
There's a great clip of it on YouTube. I don't know how to post it, maybe some one can for me
There's a great clip of it on YouTube. I don't know how to post it, maybe some one can for me
BoydAllen
Gold $$ Contributor
Ken,
If we have learned anything it is that we cannot simply build rifles based on what seems to be. Actual testing is required, and for that testing to be worth anything, it has to be very carefully done. Often, what seems logical is not the case. If you lack the resources, facilities and background to do your own testing, the best alternative is to study those whose records indicate that they consistently get the best results. One resource that I can point you to is a series of six segments of a workshop given by Jack Neary at various benchrest matches that is designed to help competitors achieve better results. You will find the videos on YouTube. Jack is a member of the Benchrest Hall of Fame, and has represented the US at the Worlds Benchrest Championship.
Cases "loose their memory" because of the fact that when the chamber and case expands when a high pressure load is fired, the increase in chamber size can exceed the elastic limit of the brass, but not the steel, so when they both snap back the steel comes back to the same dimension that it started at, but the brass does not.
One thing that I have learned along the way is that if you start out with too little clearance between brass and the chamber that it is fired in, you will run into tightness problems at lower pressures than if there is more pressure to start with.
I learned this when a friend had a Remington dimensioned 6BR chamber opened up so that Lapua brass would chamber. The result was a chamber that was smaller than one cut specifically for the larger Lapua brass, but the Remington brass would chamber without resistance. The clearance was minimal but sufficient for smooth chambering. After he had that done, he started running into tight bolt issues at lower velocities than he had before. This was remedied when he had the chamber recut with a slightly larger reamer that was dimensioned for the Lapua brass.
Later I worked on a project for a friend that involved ordering a tight neck, short throat .300 Weatherby reamer. We tested loads up to some really high pressures and to see what the cases were doing we only neck sized the case used for the test.We loaded at the range. In any case, at the end of the test, after the case had cooled from its last shot, it chambered easily. I believe that the reason for that was that I had specified the reamer with stock body diameters, having learned from my friend's 6BR experience. We took that Weatherby case well past the point of ejector marks on the head, up to the point where the belt showed expansion a second time. I do not recommend doing this.
If we have learned anything it is that we cannot simply build rifles based on what seems to be. Actual testing is required, and for that testing to be worth anything, it has to be very carefully done. Often, what seems logical is not the case. If you lack the resources, facilities and background to do your own testing, the best alternative is to study those whose records indicate that they consistently get the best results. One resource that I can point you to is a series of six segments of a workshop given by Jack Neary at various benchrest matches that is designed to help competitors achieve better results. You will find the videos on YouTube. Jack is a member of the Benchrest Hall of Fame, and has represented the US at the Worlds Benchrest Championship.
Cases "loose their memory" because of the fact that when the chamber and case expands when a high pressure load is fired, the increase in chamber size can exceed the elastic limit of the brass, but not the steel, so when they both snap back the steel comes back to the same dimension that it started at, but the brass does not.
One thing that I have learned along the way is that if you start out with too little clearance between brass and the chamber that it is fired in, you will run into tightness problems at lower pressures than if there is more pressure to start with.
I learned this when a friend had a Remington dimensioned 6BR chamber opened up so that Lapua brass would chamber. The result was a chamber that was smaller than one cut specifically for the larger Lapua brass, but the Remington brass would chamber without resistance. The clearance was minimal but sufficient for smooth chambering. After he had that done, he started running into tight bolt issues at lower velocities than he had before. This was remedied when he had the chamber recut with a slightly larger reamer that was dimensioned for the Lapua brass.
Later I worked on a project for a friend that involved ordering a tight neck, short throat .300 Weatherby reamer. We tested loads up to some really high pressures and to see what the cases were doing we only neck sized the case used for the test.We loaded at the range. In any case, at the end of the test, after the case had cooled from its last shot, it chambered easily. I believe that the reason for that was that I had specified the reamer with stock body diameters, having learned from my friend's 6BR experience. We took that Weatherby case well past the point of ejector marks on the head, up to the point where the belt showed expansion a second time. I do not recommend doing this.
ireland2,
Thank you for taking the time to explain the case stretching phenomena in some detail.
I have seen what you are describing above. I've only been neck sizing to this point but when my cases wouldn't allow the bolt to close smoothly I tried running the case up into a Redding body die. Apparently this die is long enough that the shoulder of the case does not touch the die and the case did increase in length - which only exacerbated the bolt closing problem. I should mention also that I'm using a Forster Co-Ax press so manipulations with shell holders, while possible, would require some additional effort.
I have a Redding bushing FL die on the way. That should solve my immediate problem while I continue to heighten my reloading skills.
Fascinating pastime this reloading is.
Ken
kvd. thank you, heavy case head, the case head on most of my rifles is not supported and it is said the case head protrudes. When I pull the trigger the primer is crushed, somewhere between striking the primer and the bullet leaving the case expands to fill the chamber. I am the fan of having air between the case and chamber, I do not want a lot of air but the space between the chamber and case should be filled with clean air. It takes time for the case to expand when the case confirms to the chamber; meaning I believe the extractor has more to do with the case alignment with the chamber than a heavy case head.
And then there is the ejector, some ejectors are located near the rear and have little to nothing to do with the case alignment when fired. And then there is the ejector that rest against the case head when when the bolt is closed. I insist the ejector that is located in the bolt face not support the case because that causes little round dents. In the perfect world the ejector would be flush with the bolt face. And then there is push feed, reloaders assume the extractor jumps the rim, there are time the extractor does not jump the rim until the round is fired; and that is bad because the case shoulder is pushed up against the shoulder of the chamber.
F. Guffey
BoydAllen
Gold $$ Contributor
Actually it may not. A body die gives you the same sizing that a bushing FL die would without a bushing in place. One thing that you might want to check out is whether there is any gap between the plates that function as a shell holder on your press and the bottom of your body die when a case that is being sized is in the die at its highest position. I have not checked this on a Forster press but on a Rock Chucker you can adjust a die to touch the shell holder with no case in place, and then with one in place, in the process of being sized there will be a slight gap, because of material stretch in the press linkage. In the instance where I discovered this, the gap was about .006, which effectively gave me some room for further adjustment. Don't take this too far because beyond the point where it eliminates the gap, all that happens is that excessive stress is put on the press.
If the bullet is touching the rifling, or jammed into the rifling, the only 2 parts of the round that need to touch the chamber to give perfect alignment are the case head and the bullet. A very large fraction of winning benchrest shooters have their loaded rounds set up this way. Personally, I've never had a rifle that shot smaller with bullets jumping, except when shooting solid copper bullets.
When you fire a cartridge in a chamber at reasonable pressures for your gun and cartridge, that cartridge should come out of the chamber without a problem. If it comes out without drag then it should fit back in the chamber without drag.
In order for a brass case to have drag when it is removed from the chamber the pressure has to be high enough to expand the chamber more than the brass can spring back. This can be exacerbated with soft or over-annealed brass because soft brass has less spring.
Sometimes it is necessary to over-pressure ammunition. If you need every last bit of velocity to stay above the sonic transition speeds you might have to use high pressures. If you seat the bullet into the lands you could be causing high pressure spikes. If you are loading hot and jamming the bullets into the lands you are most assuredly running pressures well above the maximum for the round and possibly the rifle.
In a competition rifle the barrel is a replacement part. They wear out and are replaced fairly often. They are also normally heavier (larger OD) than a sportsman type of barrel.
Sportsmen have no reason to load to maximum (and over maximum) pressures for their rifles and cases. As a hunter I load mid range loads where I get good accuracy with moderate pressures. Good accuracy for me is most anything under 1 MOA and using the overall length listed in the book I typically find two loads that are accurate. I can then decide if I need the higher velocity load for the distance at which the round is used.
I have been partial neck sizing (using a neck sizing die to size just part of the neck) so I have a part of the neck that fits the chamber neck and the case comes very close to filling the chamber. The only time I use my full length sizer is with cases that were fired in a different rifle. In the last 42 years (since I began using this method) I have never had to "bump the shoulder" or use a full length sizing die. I run all my cases through the trimmer even though some don't trim every time I reload. I used to check to make sure that each round would chamber but after a few years I stopped doing that because they always feed without any drag.
Use what ever pressure you need to get the job done and size your cases so they fit in your gun. Each gun is an individual and each discipline has different requirements. I rarely have to shoot beyond 200 yards to harvest game so velocity is a lesser consideration for me than someone who has to use a small cartridge with a heavy bullet to shoot 1000 yards in competition. I plan on passing down my rifles to my kids and grandchildren and I expect the guns to shoot as well for them as they do for me. The 1000 yard competitor is going to be replacing his barrel after only 2-5000 rounds. The barrels on my guns will last at least two generations and maybe longer. It is up to the individual use of the gun as to how long it will last. Reloading is all about finding out what works for you with your uses. Experimentation is the only way you will find out. Do it safely and enjoy the ride.
In order for a brass case to have drag when it is removed from the chamber the pressure has to be high enough to expand the chamber more than the brass can spring back. This can be exacerbated with soft or over-annealed brass because soft brass has less spring.
Sometimes it is necessary to over-pressure ammunition. If you need every last bit of velocity to stay above the sonic transition speeds you might have to use high pressures. If you seat the bullet into the lands you could be causing high pressure spikes. If you are loading hot and jamming the bullets into the lands you are most assuredly running pressures well above the maximum for the round and possibly the rifle.
In a competition rifle the barrel is a replacement part. They wear out and are replaced fairly often. They are also normally heavier (larger OD) than a sportsman type of barrel.
Sportsmen have no reason to load to maximum (and over maximum) pressures for their rifles and cases. As a hunter I load mid range loads where I get good accuracy with moderate pressures. Good accuracy for me is most anything under 1 MOA and using the overall length listed in the book I typically find two loads that are accurate. I can then decide if I need the higher velocity load for the distance at which the round is used.
I have been partial neck sizing (using a neck sizing die to size just part of the neck) so I have a part of the neck that fits the chamber neck and the case comes very close to filling the chamber. The only time I use my full length sizer is with cases that were fired in a different rifle. In the last 42 years (since I began using this method) I have never had to "bump the shoulder" or use a full length sizing die. I run all my cases through the trimmer even though some don't trim every time I reload. I used to check to make sure that each round would chamber but after a few years I stopped doing that because they always feed without any drag.
Use what ever pressure you need to get the job done and size your cases so they fit in your gun. Each gun is an individual and each discipline has different requirements. I rarely have to shoot beyond 200 yards to harvest game so velocity is a lesser consideration for me than someone who has to use a small cartridge with a heavy bullet to shoot 1000 yards in competition. I plan on passing down my rifles to my kids and grandchildren and I expect the guns to shoot as well for them as they do for me. The 1000 yard competitor is going to be replacing his barrel after only 2-5000 rounds. The barrels on my guns will last at least two generations and maybe longer. It is up to the individual use of the gun as to how long it will last. Reloading is all about finding out what works for you with your uses. Experimentation is the only way you will find out. Do it safely and enjoy the ride.
BoydAllen,
Thank you for another good explanation of why brass grows to the point that it will not allow smooth bolt closure. So far so good. That also explains hard bolt lift - since one now has a case in the chamber that is a few thousandths to long.
I will look up the youtube videos you mentioned. They can be an excellent source of information and learning.
Ken
BoydAllen
Gold $$ Contributor
Cases generally get tight in two places, at the shoulder, and above the head. Some time back a friend chambered up a barrel for himself in .243 AI. Since I knew that his would be pushing it to get all the velocity that he could I discouraged him from following his plan of using a home made die that would do nothing more than bump case shoulders, combined with a Lee Colle die. I told him that his cases would also get tight at the back, but since his previous experience had been with moderate loads in a .223 he did not believe me. Turns out that I was right. Since he is so Scotch about spending, and had done me some favors in the past, I went to a local gun show and picked up a used RCBS non-carbide .45 ACP die set for $10, removed everything from the sizing die body and gave it to him to use as a ring die, to size the bases of his cases. It worked fine. He is still using it.
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