Bought a Redding body die with the idea of working the shoulder of fireformed brass, then neck sizing, as opposed to FL resizing. I thought I could move the shoulder without resizing the entire case,less the neck). Tried it today; looks like the entire case body is being resized, although I do have good control of the shoulder. Does this sound right? I've always necksized until brass got tight,3-5 rounds), the FL resized and started again, but always thought I was losing a little accuracy with the FL resize cycle. If the body die resizes the entire body of the case... where is the gain?
Body Dies
- Thread starter Posit
- Start date
CatShooter
Posit said:
The body die is a FL die without the neck sizing part.
"If the body die resizes the entire body of the case... where is the gain?"
You can FL the body without touching the neck.
If you had a die that only moved the shoulder, the body would expand and get fatter under the pressure on the shoulders.
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CatShooter
Posit said:
It isn't different from FL sizing, except that you don't do the neck.
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Posit said:
If you attend a BR match and ask the shooters how they size their brass, you will find out that almost all of them FL size EVERY time. The key is to have a die that is properly made to work with the chamber in question. As CatShooter pointed out, a body die is nothing more than a FL die with no provision to size the neck. If shooting lower pressure/velocity loads, a neck die can be used between FL sizing sessions. But BR shooters have proven that FL sizing between each firing is not at all detrimental to accuracy.
OK... trying to sort all the things I know/have heard on the subject. Does mean there is no advantage to using fireformed brass, or does "die that is properly made to work with the chamber in question" mean dies which are tailored to the exact dimensions of a specific chamber? How do competition dies fit this scenario?
CatShooter
Posit said:
You are making this far more complicated then it has to be.
So I'm gonna start from the beginning.
Fire formed brass is better than new brass. It fits the chamber within a few thou all over.
It was once believed that brass MUST be fire formed to achieve maximum accuracy - there is still some truth to this, but it has been learned that ~95%-ish accuracy comes from the throat, barrel and case.
Absolutely outstanding groups have been shot with new,unfired) brass, so it is arguable that cases must be fire formed for best accuracy,though it does eliminate one more bit of slop).
Now, the fly in the ointment - cases expand when fired, and then contract a few thou, called "spring back". The actual amount depends on the state of anneal, the thickness of the section,body wall or neck).
Also, the action, bolt, and ring also stretch each time the gun is fired, so the case "springs back" a little less each time, until it is a tight fit in the chamber.
With some case designs, they never get tight, and never need bumping the shoulder... and some cases are more susceptible to it, especially when pressures are running in the mid 60's.
At one time in benchrest, this was the most desired state of a case... to keep it a "crush fit" because it meant there was no play at all, but that was back in the days of "The smallest group won".
These days, BR shooters don't stress the absolutely smallest group, it is the "Aggregate" that wins. So you can shoot one smallest group, and a bunch of dogs, and in the past you would have won the gold for the day, now you go home with doodley squat.
BR shooters will judge the wind and mirage conditions, and may fire the whole string in fairly rapid succession, when the condx meet their approval.
To be able to do this, the cases MUST be able to be chambered without any resistance that would break the string of shots, or,God forbid) cause the rifle to be moved in the bags - so an effort to open or close the bolt is not acceptable.
So it works like this - snug cases remove the last bit of slop, but may slow down loading and unloading.
Varmint shooters like snug cases, because when they are snug, case growth is at a minimum... BR shooters like their case to have a few thou around the case for ease of loading and unloading.
Each time you move the shoulder,and reduce the body diameter), by sizing with a FL or "body die", there will be an initial stage of stretch of the case until it gets back into it "happy fit stage"
Now, when/,if) the gets too tight a fit for your use, you have the choice of tossing it in the trash, or using a FL/Body die to start the cycle all over again.
Also keep in mind that NO sizing die will match your case/chamber exactly, so when you think you are just moving the shoulder back a few thou, you are actually moving some of the shoulder back many thou, and you may be reshaping the shoulder/body junction, or the neck/shoulder junction... and all of these parts of the case must go back into place on the next firing.
I have 7 high quality .223 rifles, and the fired cases from them are enough different that I can hold them in my hand and see differences in the shoulders and neck junctions. No die can just bump the shoulders on all of them - that's why a body die brings the case back to minimum dimensions to start all over again.
I hope that this clears some of this stuff up for you.
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BoydAllen
Gold $$ Contributor
There is a better way to get a good match between a die and chamber. Start with the die. I have done a half dozen or so projects where we started with a one piece FL die, sized fired cases, and then designed a reamer to match. Due to the dies neck dimensions, these had to be "tight neck" chambers. One of the most highly esteemed reamer manufacturers agrees with me that doing it this way is an easier way to come up with a good match.
Also, in short range benchrest, many times conditions are not suitable for "running" a group. This is when conditions are switching too quickly for that technique.
Another reason that using a well designed FL die every time is a good idea is that all cases in a given set do not get tight in the chamber at exactly the same rate, and it has been my experience that if cases used within the same group have significantly different bolt closing force requirements, the group will be enlarged.
Also, in short range benchrest, many times conditions are not suitable for "running" a group. This is when conditions are switching too quickly for that technique.
Another reason that using a well designed FL die every time is a good idea is that all cases in a given set do not get tight in the chamber at exactly the same rate, and it has been my experience that if cases used within the same group have significantly different bolt closing force requirements, the group will be enlarged.
Forum Boss
Administrator
Boyd, I'm not trying to be a wise guy here, but if you start with a die,,and no reamer), how does one produce the fired cases to send to the reamer-maker?
Does this assume one must shoot the brass in another gun with a pretty similar chambering?
Does this assume one must shoot the brass in another gun with a pretty similar chambering?
I guess you could shoot a few cases out of a factory gun,generous chamber to expand the brass) then FL resize the cases with the die and send them off?
BoydAllen said:
I have noticed that myself in my 6br. It shoots the best every time with fireformed brass but the groups get larger as the bolt closing force starts to change from round to round. Then after a couple shots the bolt gets too hard for comfort and I have to start all over again. Then after a FL resize it doesnt shoot good at all. I have played with the shoulder bump from .001 out to .006 and nothing works as well as fire formed. Do I need to be looking for a different die/dies? Im using a Forester for FL and a collet die for the neck size only.
Boyd
I had this exact same discussion with my gunsmith about a month or two ago. Why is it that we make these tight chambers and necks and then we are forced to use dies that do not match our chambers worth a hoot. This ofcourse does not affect you if you use a costom die blank and reamer. which adds to the cost of the project even more.
I was thinking if I new the exact dimension of the Die makers reamer or chamber of the die I could have Dave Kiff make me a reamer to a half thou at the base bigger and 1 thou at the shoulder and I would be golden. No more messing around just run it in the die and go shoot. Very little sizing of the case and over working of your brass which should lead to longer case life. : ) Instead we purchase a FL die and or a body die and a neck die and a seater.
The die is a very important part of the system, just as much as the powder and primer choice or even the scope on your gun. for a factory chambering of a good tactical rifle or a Palma rifle or non benchrest gun this would seem to be a logical move, too me it seems anyway.
Maybee Im missing somthing?
RussT
I had this exact same discussion with my gunsmith about a month or two ago. Why is it that we make these tight chambers and necks and then we are forced to use dies that do not match our chambers worth a hoot. This ofcourse does not affect you if you use a costom die blank and reamer. which adds to the cost of the project even more.
I was thinking if I new the exact dimension of the Die makers reamer or chamber of the die I could have Dave Kiff make me a reamer to a half thou at the base bigger and 1 thou at the shoulder and I would be golden. No more messing around just run it in the die and go shoot. Very little sizing of the case and over working of your brass which should lead to longer case life. : ) Instead we purchase a FL die and or a body die and a neck die and a seater.
The die is a very important part of the system, just as much as the powder and primer choice or even the scope on your gun. for a factory chambering of a good tactical rifle or a Palma rifle or non benchrest gun this would seem to be a logical move, too me it seems anyway.
Maybee Im missing somthing?
RussT
BoydAllen
Gold $$ Contributor
The projects that I was speaking of were done in calibers where fired brass was available. It can be range brass, or from any other source as long as it is reduced in all dimensions when sized by the FL die. Older,more fired brass has more spring back and since it represents the largest sized product that the die will produce, is what you want for this application. Once the brass is sized, all that remains is to decide on neck clearance and tension desired, as well as body clearance. For my PPC, I shoot for .0005 at the shoulder, and about .001 about .3 up from the case head. There is a little more to it than I have written here, but then this is not an article, just a suggestion.
Nonliberal,
What is the runout of your FL sized cases, and how much is the body reduced in diameter at the shoulder and about .3 up from the head? You might need a custom FL die.
Nonliberal,
What is the runout of your FL sized cases, and how much is the body reduced in diameter at the shoulder and about .3 up from the head? You might need a custom FL die.
CatShooter
It would be best to take a Cerosafe cast of the die, and then make the reamer three or four thou over... then the sizing die would have an effect of actually resizing the case.
Using pick-up brass, or brass from someone else's rifle that was sized, can not give you an accurate reamer, because the sized case does NOT accurately represent the die's inner measurements....
If you are after big records, it is probably worth it, but I think that one has to weigh the cost and "headache" factor of some of the anal stuff, to the payback factor.
At what point do you say, "enough"... if you are after records, I guess that point is when your wife starts to become your "Ex".
But if you are a long range shooter,Bench or varmint), much of this will never be seen at the target.
.
Using pick-up brass, or brass from someone else's rifle that was sized, can not give you an accurate reamer, because the sized case does NOT accurately represent the die's inner measurements....
If you are after big records, it is probably worth it, but I think that one has to weigh the cost and "headache" factor of some of the anal stuff, to the payback factor.
At what point do you say, "enough"... if you are after records, I guess that point is when your wife starts to become your "Ex".
But if you are a long range shooter,Bench or varmint), much of this will never be seen at the target.
.
BoydAllen
Gold $$ Contributor
Because brass has spring back, the important thing is to have a chamber that fits the sized brass from that particular die. Using cerrosafe on the die leaves you guessing as to what the spring back will be. A sized case from the die gets around the problem. As an example, the second project of this type that I did involved an ordinary RCBS FL die in .223 caliber. What we ended up with is a tight neck reamer that was just barely larger than a sized case from that die. We also hit the neck tension right on the money.,The expander ball was ground down so that it did no work.) This setup produces extremely straight sized brass, and accuracy oh a par with a true Benchrest rifle. Of course this was with a top grade match barrel, and all the other details properly done. As brass is used it work hardens, giving more spring back. Using well used fired brass to access the die for reamer design gives a worst case measurement that insures that the die will continue to size effectively toward the end of a case's service life. As close as we are fitting things, if we started out with once fired brass, eventually the increasing spring back of the brass from repeated firing and sizing would mean that the die would not be small enough to size the case to give the desired fit.
BoydAllen said:
I have a concentricy guage on the way. The body is reduced at the shoulder .004. .3 up from the head is reduced .001.
One thing that I have noticed is
all the fired cases that started as virgin brass are 1.5585 but grow to anywhere from 1.566-1.571 when FL resized.
The virgin brass starts out at 1.554 but grows to 1.557 just from FL resizing without being fired..
Even virgin brass shoots good, basicly everything that DOES'NT go through the FL resizing die works well.
Is this Forester die That says 6BR REM causing my problem? I thought it would when I bought it but was told it should work fine.
Chamber is a 6br Norma .272 no turn neck chambered by Shilen.
Shoulder bump guage. I believe its a Stoney point but Im not positive.
I bought two barrels at the same time and just put the other barrel on a different gun. Same situation, it shoots virgin brass well, then fireformed well, then .75 groups with FL resize.
Im stumped.
Shoulder bump guage. I believe its a Stoney point but Im not positive.
I bought two barrels at the same time and just put the other barrel on a different gun. Same situation, it shoots virgin brass well, then fireformed well, then .75 groups with FL resize.
Im stumped.
BoydAllen
Gold $$ Contributor
I think that you need another FL die. What is your loaded neck dia. over the pressure ring at the base of the bullet if that applies, if not, over the shank? I am trying to find out if you can take a skim cut, that cleans up the neck at least 3/4 of the way around, so that you will end up with reasonably uniform neck tension if you use a FL die that takes bushings and does not use an expander ball. Can you feel the expander drag? Have you checked your runout,FL sized)with a concentricity gage? If the expander is dragging, what is the difference between the necks of FL sized brass with and without the expander in place?
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