Neck sizing question
- Thread starter Nude nut
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I have neck sizing dies, I do not use them but I have them. I have full length sizing dies, I can neck size with a full length sizing die, I don’t but I can. If I choose to neck size with a full length sizing die I understand I am changing a few factors and there is a chance the upsized protein of the neck could aid in case alignment in the chamber.
Now we have to go back and correct the claim made about the ‘bench rest boys’; it is claimed the ‘bench rest boys’ went to full length sizing years ago and everyone is supposed to know it. They ‘the bench rest boys’ never list the difference between the chambers and sized case dimension but they all seemed to have their favorite die maker.
What does this mean? Has the ‘bench rest boys’ gone to neck sizing? It makes sense; the fired case will fit the chamber like a glove; I know, after 4 or 5 firings the case must be full length sized to start over? If the case has been fired 5 times how is it possible to start over?
F. Guffey
I necksize for first 3 firings then full length size bumping shoulder 1 thou with a body die then run necks through a .336 bush in nk die only sizing a 1/3 of the neck where the bearing surface/boat tail junction ends.
Then run them through a expander die with madrel this leaves to 2/3 of the neck still in a fired state.
I do not neck turn at this stage but have all the gear to do so I do anneal every firing after the first three firings of nk sized only brass the chamber is a no nk turn .342 neck.
This sizing method is producing great accuracy with my load my main concern is the unzised portion of the neck that is still in a fired state could it cause unexpected pressure problem maybe hard chambering I dont know.
Cheers Trev.
Then run them through a expander die with madrel this leaves to 2/3 of the neck still in a fired state.
I do not neck turn at this stage but have all the gear to do so I do anneal every firing after the first three firings of nk sized only brass the chamber is a no nk turn .342 neck.
This sizing method is producing great accuracy with my load my main concern is the unzised portion of the neck that is still in a fired state could it cause unexpected pressure problem maybe hard chambering I dont know.
Cheers Trev.
Dusty Stevens
Shiner
If neck sizing youll eventually have to fl size then there goes consistency. Havent seen a neck die used in br in my career (since 1999) and dont think they were used at all to speak of since the 50's in any serious accuracy application. Neck sizing in an accuracy application is just a myth that wont die for whatever reason.
Dusty,
If you read my post above yours I do full legth resize I tried to research what im asking prior to me posting and everything I read ended up the same a Nk size/Fl size debate and never gets to the point of will the unsized portion of the neck cause any problems at some stage.
I myself dont shoot br I shoot F standard not reconized in your neck of the woods I think its where fclass started then came ftr and open so I dont require 1/8 1/4 moa accuracy be nice but not required.
Cheers Trev.
Dusty Stevens
Shiner
No trev i knew what you were saying. Wasnt directed at you
My reply wont answer the question either but will probably show up another potential problem.I bought a 338lm and I do exactly what you do exept that the 338 bullet seat all the way past the neck sholder junction and I leave a 1/4 neck unsized. Nothing went wrong with groups or chambering the round. My 338 lapua has a generous neck clearance of about .009.
What I noticed from shot 3 and on is that there was a lot of brass flow from the sholder into the neck. I could literally see that sharp edge that the neck cutter made between the neck and sholder junction moving up the neck after every shot a tiny bit at a time. At this stage I could feel a two step seating of the bullet. An easy first stage followed by some resistace what I think is the neck junction moving up the neck.
By the time it moved all the way past the sized part of the neck, seating became such an issue that I desided to cut the necks again after a full size at shot 13. As expected only the last unsized bit of the necks had material removed.
Unfortunately as I stated my post wont give you answers either because prior to the cutting of the necks I had to go buy a new batch of powder that is slower burning than the previous and the neck cutting was part of a remedy to make the new batch powder group.
I also decided to do away with leaving the last 1/4 of the necks unsized because the question is does this practice aided in the brass flow into the necks. Im on my second firing after cutting and the two step seating improved to the point where it is not bothersome and the new batch powder produce some exelent results on ES and grouping. I had exelent results with not sizing the last bit also.
Got to do alot more shooting to see if the brass flow issue will manifest again and how seating and grouping will progress. I still have no idea if this issue is caliber specific, a function of the unsized bit or annealing or a combination.
What I noticed from shot 3 and on is that there was a lot of brass flow from the sholder into the neck. I could literally see that sharp edge that the neck cutter made between the neck and sholder junction moving up the neck after every shot a tiny bit at a time. At this stage I could feel a two step seating of the bullet. An easy first stage followed by some resistace what I think is the neck junction moving up the neck.
By the time it moved all the way past the sized part of the neck, seating became such an issue that I desided to cut the necks again after a full size at shot 13. As expected only the last unsized bit of the necks had material removed.
Unfortunately as I stated my post wont give you answers either because prior to the cutting of the necks I had to go buy a new batch of powder that is slower burning than the previous and the neck cutting was part of a remedy to make the new batch powder group.
I also decided to do away with leaving the last 1/4 of the necks unsized because the question is does this practice aided in the brass flow into the necks. Im on my second firing after cutting and the two step seating improved to the point where it is not bothersome and the new batch powder produce some exelent results on ES and grouping. I had exelent results with not sizing the last bit also.
Got to do alot more shooting to see if the brass flow issue will manifest again and how seating and grouping will progress. I still have no idea if this issue is caliber specific, a function of the unsized bit or annealing or a combination.
BoydAllen
Gold $$ Contributor
A little about the way that top of shoulder brass ends up in the bottom of the neck:
On the initial firing, there is usually more shoulder to chamber clearance than after the first firing. When the round is fired, the combined effect of the energy of the firing pin strike, and the force of the primer against the bottom of the primer pocket shoves the case forward, until the case shoulder stops against the chamber's shoulder. In the case of cartridge designs that have smaller shoulder angles, this collision forces a little of the shoulder up into the bottom of the neck, because brass is malleable. As the pressure in the body of the case builds, the friction between the case body and the chamber keeps the case in this forward position. There is clearance between the case head and the bolt face, until the pressure builds to the point where it exceeds the yield strength of the brass, which causes the case to stretch slightly (as well as become slightly thinner), just above the solid part of the head. This brings the head into contact with the bolt's face. Due to the springy nature of the brass, because it has been work hardened during manufacture, if the peak pressure of the load was not excessive, as the pressure diminishes, the case becomes slightly smaller than the chamber, which allows it to be extracted without undue effort. If the case is then reloaded, and FL sized in the process, depending on how much the diameter of the case is reduced by sizing, and how far back the shoulder is bumped, brass is forced from the top of the shoulder into the bottom of the neck. The best way to slow this process is to use a die that only slightly reduces the body of the case, and to set the die so that the shoulder is bumped back the absolute minimum required for consistent chambering without excessive effort. From a cartridge design point of view, cases that have sharper shoulder angles are not as easily driven forward during firing. If you are seeing an excessive movement of brass from the top of the shoulder into the bottom of the neck, you should measure how much your die is reducing the diameter of the body of your cases, and how much you are bumping back shoulders. Annealing to too soft a condition in shoulders can also cause problems. Generally, it has been my experience that leaving part of the neck unsized has not caused any problems. Properly adjusted FL dies that closely match the chambers that that they are used with are IMO an important part of the accuracy equation.
On the initial firing, there is usually more shoulder to chamber clearance than after the first firing. When the round is fired, the combined effect of the energy of the firing pin strike, and the force of the primer against the bottom of the primer pocket shoves the case forward, until the case shoulder stops against the chamber's shoulder. In the case of cartridge designs that have smaller shoulder angles, this collision forces a little of the shoulder up into the bottom of the neck, because brass is malleable. As the pressure in the body of the case builds, the friction between the case body and the chamber keeps the case in this forward position. There is clearance between the case head and the bolt face, until the pressure builds to the point where it exceeds the yield strength of the brass, which causes the case to stretch slightly (as well as become slightly thinner), just above the solid part of the head. This brings the head into contact with the bolt's face. Due to the springy nature of the brass, because it has been work hardened during manufacture, if the peak pressure of the load was not excessive, as the pressure diminishes, the case becomes slightly smaller than the chamber, which allows it to be extracted without undue effort. If the case is then reloaded, and FL sized in the process, depending on how much the diameter of the case is reduced by sizing, and how far back the shoulder is bumped, brass is forced from the top of the shoulder into the bottom of the neck. The best way to slow this process is to use a die that only slightly reduces the body of the case, and to set the die so that the shoulder is bumped back the absolute minimum required for consistent chambering without excessive effort. From a cartridge design point of view, cases that have sharper shoulder angles are not as easily driven forward during firing. If you are seeing an excessive movement of brass from the top of the shoulder into the bottom of the neck, you should measure how much your die is reducing the diameter of the body of your cases, and how much you are bumping back shoulders. Annealing to too soft a condition in shoulders can also cause problems. Generally, it has been my experience that leaving part of the neck unsized has not caused any problems. Properly adjusted FL dies that closely match the chambers that that they are used with are IMO an important part of the accuracy equation.
BoydAllen, headspace is set at 1/1000" but I do anneal quite soft. Guess Im goiing to cut flame time on this batch. I also think that the .009 neck clearance is bit high so the next batch wont get their necks turned that may reduce brass flow also.
I use a Redding body die to get a close fit not much further I can do about that issue
I use a Redding body die to get a close fit not much further I can do about that issue
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A problem? There should be factors to consider, no where is it said or written the answer is reducing the problem. The answer should be about the differences between neck sizing and full length sizing, in the absence of factors it always turns in the 'debate'.
F. Guffey
.001" head space? I would say the length of the chamber from the shoulder to the bolt face is longer by .001" than the case from the shoulder of the case head. Both the case and chamber can not have head space. If the case is shorter than the chamber I would think the difference in the two lengths would be called clearance. I am the fan of cutting down on all that case travel. I off set the length of the chamber with the length of the case.
F. Guffey
High pressure expands the case to the extents of the chamber which also expands to some degree dependent on the pressure levels being restrained, then as pressure diminishes and unless the yield strength of the barrel steel has been exceeded, the chamber “remembers” and returns to its original dimensions. And, the case:
“… Due to the springy nature of the brass, because it has been work hardened during manufacture, if the peak pressure of the load was not excessive, as the pressure diminishes, the case becomes slightly smaller than the chamber, which allows it to be extracted without undue effort. …”
Quote BoydAllen
Got a question, only ‘cause I wanna know.
Assume that peak pressure was excessive so now there’s bolt click on extraction, or a case stuck inside the chamber. Is it because the excessively high pressure changed the brass properties such that it’s lost its “memory”, or, is it that the chamber’s expansion and so the case’s expansion right along with it, was so great that the amount of the expansion equaled or exceeded the amount that the case was able to contract?
After someone answers your question I have one. If the shoulder of the case hits the shoulder of the chamber what happens between the case head and bolt face? I have killer firing pins, my firing pins crush the primer before the case and powder and bullet know their little buddy, the primer, has been crushed. And then it all happens so fast. I have fired many cases that show the shoulder never moved when fired. I have fired 8mm57 ammo in 8mm06 chambers. I understand this is going to be confusing to most but the shoulder of the 8mm57 case was .127” from the shoulder of the chamber when fired. Had the case taken off in a dead run when driven forward by the ‘firing pin strike’ and then stopped when the shoulder of the case collided with the shoulder of the chamber what happened between the case head and bolt face? I have always said the shoulder of the case did not move.
But ever time the subject comes up someone goes off in lofty terms and starts with “the firing pin strikes the primer and then the whole thing, the case, powder, bullet and primer takes off for the front of the chamber”. And then I always wonder if anyone has ever weighted the bullet, powder, case and primer to determine the gross weight etc. etc. Anyhow, I have killer firing pins.
There was a fairlure of a new rifle to fire 20 new cases at the range. I suggested the call Ruger and R-P. Instead they brought the 5 failed to fire cases to me, the cases had been hit with firing pins from 4 different rifles for at least 5 attempts; nothing.
I pulled the ammo down, removed the primers, then installed the primers back in the same cases they were removed from. I then chambered the empty cases in one of my M1917s and crushed the primers. When the cases were ejected the primers were not protruding, all of that without powder, without bullets.
F. Guffey
There were 5 out of 20 rounds that failed to fire.
BoydAllen
Gold $$ Contributor
Both the chamber and the case expand under high pressure. The chamber returns to its original size, but the brass does not come all the way back to its original size, because it retains some malleability, even though it has been work hardened.
In the case of a "click" a the top of the bolt handle stroke, on opening, the solid part of the case head has expanded like a raw hamburger patty pressed between the palms of your hands. Usually this takes more than one shot. The reason that it happens is that the chamber fits the unfired brass too closely, and the coverage of the sizing die may not be quite the same as the chamber, when the die is set for proper shoulder bump, leaving a very thin band of area just above the solid head unreachable by the working ID of the die. A small base die may pull down the area by reducing the area next to it, but if the head has expanded too much, even though the loaded round chambered smoothly, after the round is fired, the click may return, unless the problem was simply that the die was too large for the chamber and it took several firings for this to show up.
Years back, I had a single 6PPC case that had developed a click. It was part of a set that got used to experiment with different loads. Evidently it had been fired with hot loads to the point where this problem occurred. I decided to do an experiment. I seated a bullet in the neck so that I could chuck the case neck in my cordless drill, and holding the opposite side of the case body against something for support, I used a coarse diamond lap, held parallel with the CL of the case, to remove a couple of thousandths from the bottom of the case, starting at the top of the extractor groove. After that I polished the cut with some 0000 steel wool. Then I loaded and fired the case with a stout load a few times. (loading at the range) using the same FL die that I had when the click appeared, and there was no click. If my chamber had been just a little larger at the very back, there would have been more room for the solid head of the case to expand without interference. We tend to assume that tighter clearances in all areas are good. In some cases this is not the case. I have a barrel that is is just a little larger in this area, and it is every bit as accurate as those that would be more prone to having click issues with hot loads. This has not been a problem for me because I have not found my most consistent accuracy at the top accuracy node, so my cases generally do not have click issues. If you like to run hot all the time, you might want to pay some attention to chamber design when you are ordering your next reamer.
In the case of a "click" a the top of the bolt handle stroke, on opening, the solid part of the case head has expanded like a raw hamburger patty pressed between the palms of your hands. Usually this takes more than one shot. The reason that it happens is that the chamber fits the unfired brass too closely, and the coverage of the sizing die may not be quite the same as the chamber, when the die is set for proper shoulder bump, leaving a very thin band of area just above the solid head unreachable by the working ID of the die. A small base die may pull down the area by reducing the area next to it, but if the head has expanded too much, even though the loaded round chambered smoothly, after the round is fired, the click may return, unless the problem was simply that the die was too large for the chamber and it took several firings for this to show up.
Years back, I had a single 6PPC case that had developed a click. It was part of a set that got used to experiment with different loads. Evidently it had been fired with hot loads to the point where this problem occurred. I decided to do an experiment. I seated a bullet in the neck so that I could chuck the case neck in my cordless drill, and holding the opposite side of the case body against something for support, I used a coarse diamond lap, held parallel with the CL of the case, to remove a couple of thousandths from the bottom of the case, starting at the top of the extractor groove. After that I polished the cut with some 0000 steel wool. Then I loaded and fired the case with a stout load a few times. (loading at the range) using the same FL die that I had when the click appeared, and there was no click. If my chamber had been just a little larger at the very back, there would have been more room for the solid head of the case to expand without interference. We tend to assume that tighter clearances in all areas are good. In some cases this is not the case. I have a barrel that is is just a little larger in this area, and it is every bit as accurate as those that would be more prone to having click issues with hot loads. This has not been a problem for me because I have not found my most consistent accuracy at the top accuracy node, so my cases generally do not have click issues. If you like to run hot all the time, you might want to pay some attention to chamber design when you are ordering your next reamer.
The case loses its memory is when the elastic limit is exceeded or it is annealed due to exposure to high temperature.
Assuming the second scenario there are several other factors that act at the same time.
1. The receiver ring stretches slightly and the bolt head compresses. This can be significant in a rear locking action especially when used with high pressure ammo.
2. A very tapered case expands with the chamber and the receiver and bolt return to original length wedging the tapered case into the chamber just like a self locking Morse taper
3. The chamber also contracts back on the brass as you stated below.
4. Finally if your brass is cruddy and the chamber surface texture is relatively rough such as a 63 RMS finish that was never polished after reaming your brass can be ironed into the surface texture. (See national standard ASME 46.1 for a complete explanation of surface texture, waviness and lay.)
See Varmit Al's site for his finite element analysis (FEA) of the effect of surface texture and coefficient of friction on brass flow.
http://www.varmintal.com/a243z.htm
http://www.varmintal.com/afric.htm
Don't worry if you do not recognize or comprehend all of the terminology on the first reading.
It will slowly sink in with multiple visits to his site.
Assuming the second scenario there are several other factors that act at the same time.
1. The receiver ring stretches slightly and the bolt head compresses. This can be significant in a rear locking action especially when used with high pressure ammo.
2. A very tapered case expands with the chamber and the receiver and bolt return to original length wedging the tapered case into the chamber just like a self locking Morse taper
3. The chamber also contracts back on the brass as you stated below.
4. Finally if your brass is cruddy and the chamber surface texture is relatively rough such as a 63 RMS finish that was never polished after reaming your brass can be ironed into the surface texture. (See national standard ASME 46.1 for a complete explanation of surface texture, waviness and lay.)
See Varmit Al's site for his finite element analysis (FEA) of the effect of surface texture and coefficient of friction on brass flow.
http://www.varmintal.com/a243z.htm
http://www.varmintal.com/afric.htm
Don't worry if you do not recognize or comprehend all of the terminology on the first reading.
It will slowly sink in with multiple visits to his site.
We all understand the shell holder prevents the case head from being sized, then there are small base dies, we all know the small base die does not size the base of the case. That should cause some to wonder if the stout loads are working.
F. Guffey
BoydAllen
Gold $$ Contributor
fguffey,
Perhaps you need to consider that posts go out to the world, and that readers may not know as much as you give them credit for. Just to make what I wrote more clear, I was not referring to the role of the shell holder in my previous post. Dies typically have generous chamfers or radii at their openings, and in that area they do not size. Another thing that can play a role is how long the body part of the chamber is compared to that of the die. If the gunsmith barely breaks the edge of the chamber, and cuts the tenon so that there is minimal clearance between the end of the bolt and the back of the chamber, the chamber may go farther down the case than the die, if the die is properly adjusted. Like a lot of things, this is not as simple as it might seem to be on first glance, but since you are aware of all of the variables, you will understand that this clarification is written for others who may also be reading it.
Boyd
Perhaps you need to consider that posts go out to the world, and that readers may not know as much as you give them credit for. Just to make what I wrote more clear, I was not referring to the role of the shell holder in my previous post. Dies typically have generous chamfers or radii at their openings, and in that area they do not size. Another thing that can play a role is how long the body part of the chamber is compared to that of the die. If the gunsmith barely breaks the edge of the chamber, and cuts the tenon so that there is minimal clearance between the end of the bolt and the back of the chamber, the chamber may go farther down the case than the die, if the die is properly adjusted. Like a lot of things, this is not as simple as it might seem to be on first glance, but since you are aware of all of the variables, you will understand that this clarification is written for others who may also be reading it.
Boyd
I was, I said a stout load can upset the case head and expand the flash hole and increase the diameter of the primer pocket and then there is that part about how thick the case head is from the top of the cup above the web to the case head. And then there is case head protrusion and unsupported case head. We all know the shell holder deck height is .125" or we should know and there is the radius in the opening of the die.
I have dies that are mistakes, forget the radius, the opening on two 30/06 die is .4.65", the dies keep every case that is stuffed into them. The die will not size the case head, the thicker the case head the more difficult the case is to size. I have 30/06 cases with case heads that are .200", I have case heads that are .260" thick. Again, stout loads can complicate the life of a reloader when it comes to sizing.
And still I wonder about that case taking off for the shoulder of the chamber when driven by the firing pin? I am told the shoulder collides with the shoulder of the chamber. I am starting to believe it all happens so fast no one is capable of keeping up with it. They just break into that old saying "The firing pin strikes the primer and then the whole shebang takes off as in the case, powder, bullet and primer and then stops when the shoulder of the case hits the shoulder of the chamber etc. etc." I have shoulders on cases that never move when fired, same when case forming, when I form cases I have shoulder on cases that never move.
F. Guffey
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