My point exactly, those instructions are for the the lowest common denominator reloader. They will resize the brass WAY down in excess of what is needed.
REAL differences in sizing methods?
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My point exactly, those instructions are for the the lowest common denominator reloader. They will resize the brass WAY down in excess of what is needed.
OK, after almost year later, this thread makes a lot more sense than it did before.
Woods, I got a long question now: What I think I am seeing is that if I bump the shoulder .001 to .002 off the chamber datum and I leave part of the neck unsized, then the amount of "wallow" in the bottom of the chamber that the shoulder setback alone would cause will be potentially minimized, leaving only the diffefence between the chamber ID and the unsized case neck OD as the amount of "off-center" alignment that the bullet starts out with (assuming necks have been turned to a consistent thickness).
Question is, how much of the neck do should I leave unsized? IOW, how thick does that washer need to be? Do I size only enough of the neck to grip all of the bullet and no more? IOW, would the answer be (warning, math involved!
):
Knowns:
a. (COAL, ogive)
b. (bullet length from the ogive to the base).
c. Trimmed case length
Derived:
d. (a-c) = exposed bullet (from ogive)
e. (b-d) = bullet in case neck
(e) would be the amount of neck that you would size since that would correlate to the amount of bullet in the brass.
Essentially this takes all the knowns/established characteristics and determines the MINIMAL adjustments to be made to the brass.
You could work from the case head to be safe from case length variations, but the idea would be the same. Also, this would have to be a bullet specifc calculation and the bullet would have to be set at the same depth each time.
I know this is a little egg-heady and probably over engineered since it doesn't need to be THAT exact, but let me know if this is the right idea. At any rate, you want to leave as much of the case neck unsized as possible, correct?
This should be fairly easy to accomplish with washers, with the equation giving you a fairly specific neck area that you MUST size at a minimum.
Specs for my chamber: 2.0375", bolt face to datum. I will be bumping shoulders from 2.0365" to 2.035". Dont know how .0015 exact I can really get with the bump die.
Thanks for the help with this one.
Woods, I got a long question now: What I think I am seeing is that if I bump the shoulder .001 to .002 off the chamber datum and I leave part of the neck unsized, then the amount of "wallow" in the bottom of the chamber that the shoulder setback alone would cause will be potentially minimized, leaving only the diffefence between the chamber ID and the unsized case neck OD as the amount of "off-center" alignment that the bullet starts out with (assuming necks have been turned to a consistent thickness).
Question is, how much of the neck do should I leave unsized? IOW, how thick does that washer need to be? Do I size only enough of the neck to grip all of the bullet and no more? IOW, would the answer be (warning, math involved!
): Knowns:
a. (COAL, ogive)
b. (bullet length from the ogive to the base).
c. Trimmed case length
Derived:
d. (a-c) = exposed bullet (from ogive)
e. (b-d) = bullet in case neck
(e) would be the amount of neck that you would size since that would correlate to the amount of bullet in the brass.
Essentially this takes all the knowns/established characteristics and determines the MINIMAL adjustments to be made to the brass.
You could work from the case head to be safe from case length variations, but the idea would be the same. Also, this would have to be a bullet specifc calculation and the bullet would have to be set at the same depth each time.
I know this is a little egg-heady and probably over engineered since it doesn't need to be THAT exact, but let me know if this is the right idea. At any rate, you want to leave as much of the case neck unsized as possible, correct?
This should be fairly easy to accomplish with washers, with the equation giving you a fairly specific neck area that you MUST size at a minimum.
Specs for my chamber: 2.0375", bolt face to datum. I will be bumping shoulders from 2.0365" to 2.035". Dont know how .0015 exact I can really get with the bump die.
Thanks for the help with this one.
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woods
Well-Known Member
Hey tlk, I had to go back and reread all my old posts to see if I still agreed with myself!
Your question is an interesting one (to a certified case prep nut) and is making my head hurt with thinking about all the minute variable that would have an effect.
1. case body size and how much play there is around the case body when chambered
2. if the ejector button is exerting force to push the case body to one side or just in a straighforward direction
3. if your action is square with the chamber
4. if there is runout on the neck that would make the neck closer to one side than the other even if the case body is centered
5. if there is runout on the bullet that would make all this immaterial
6. the length of the neck and the bearing surface of the bullet
7. if you have a do-nut, even if undetectable by conventional methods
8. the consistancy of your neck brass thickness
I would think that you would want enough of the neck left fire formed size to actually keep the case neck of the load centered. IOW if there was only a small part of the neck left fire formed then the competing forces of the bolt face or case body if they were pushing the case to the side would negate the centering ability. But you do want enough of the bullet left in contact with the neck to stabilize bullet grip.
But, if you turned your brass to within .0005" variation, sized your case body so it would not contact the chamber, left the shoulder so it would have very slight contact, did not have any runout on the sized portion of the neck, used a very good bullet and used a very good competition seating die, then I would think that you need to look at the caliber and neck length.
In this pic the caliber is 300 win mag and the neck is only .264" at best and the washer is .100"
that is a significant percentage of the neck. The chamber neck is ~.341", the loaded OD is .336" so the dimensional difference is ~.005".
But in this pic the caliber is 30-06 and the neck is .389"
and there is plenty of neck to work with. Perhaps a double washer would be possible. The chamber neck on this factory rifle is ~.3405", the loaded OD is .3320" so the dimensional difference is .0085".
In this pic the caliber is a tight necked 280AI
there is plenty of neck to work with but I set it up so there is .002" to .003" neck clearance so the portion of neck left fire-formed size is all but undetectable.
To me the best use of leaving part of the neck fire formed size would be in factory chambers with a lot of clearance around the neck. Those would be the ones that would be the furthest from centered if the case neck were tight to one side of the chamber neck.
So the length of the bullet bearing surface left exposed is of little consequence as long as runout is kept in check.
Your question is an interesting one (to a certified case prep nut) and is making my head hurt with thinking about all the minute variable that would have an effect.
1. case body size and how much play there is around the case body when chambered
2. if the ejector button is exerting force to push the case body to one side or just in a straighforward direction
3. if your action is square with the chamber
4. if there is runout on the neck that would make the neck closer to one side than the other even if the case body is centered
5. if there is runout on the bullet that would make all this immaterial
6. the length of the neck and the bearing surface of the bullet
7. if you have a do-nut, even if undetectable by conventional methods
8. the consistancy of your neck brass thickness
I would think that you would want enough of the neck left fire formed size to actually keep the case neck of the load centered. IOW if there was only a small part of the neck left fire formed then the competing forces of the bolt face or case body if they were pushing the case to the side would negate the centering ability. But you do want enough of the bullet left in contact with the neck to stabilize bullet grip.
But, if you turned your brass to within .0005" variation, sized your case body so it would not contact the chamber, left the shoulder so it would have very slight contact, did not have any runout on the sized portion of the neck, used a very good bullet and used a very good competition seating die, then I would think that you need to look at the caliber and neck length.
In this pic the caliber is 300 win mag and the neck is only .264" at best and the washer is .100"
that is a significant percentage of the neck. The chamber neck is ~.341", the loaded OD is .336" so the dimensional difference is ~.005".
But in this pic the caliber is 30-06 and the neck is .389"
and there is plenty of neck to work with. Perhaps a double washer would be possible. The chamber neck on this factory rifle is ~.3405", the loaded OD is .3320" so the dimensional difference is .0085".
In this pic the caliber is a tight necked 280AI
there is plenty of neck to work with but I set it up so there is .002" to .003" neck clearance so the portion of neck left fire-formed size is all but undetectable.
To me the best use of leaving part of the neck fire formed size would be in factory chambers with a lot of clearance around the neck. Those would be the ones that would be the furthest from centered if the case neck were tight to one side of the chamber neck.
So the length of the bullet bearing surface left exposed is of little consequence as long as runout is kept in check.
Autorotate19
Well-Known Member
Wow, my head hurts after reading this whole thing.... I'm bringing it up for another question. I am wanting to do the same thing. Partial fl size to bump shoulder back a couple thousands. I cant remember who told me to do this but they said to run my 7mm case through a .30 cal expander ball. Then run the 7mm case in the 7mm fl sizing die turning it down slowly and check it in my rifle until I get a slight crush fit. That will give me that slight bump Im wanting without a bunch of measuring tools, etc..... When I did this process, my crush fit ended up having a small donut or unsized portion of the neck. It is a factory chamber, and from what Iv read above means that the slight donut in the neck will keep cartridge lined up in the chamber, right? Im sorry but you guys are hard to keep up with who is telling who what............. Id appreciate the help! Thanks
woods
Well-Known Member
Hey ov, nice Elk!
So if you expand the neck with a 30 caliber expander and then start sizing it with a 7mm FL die, are you using the 7mm expander during this resizing?
If you are then you could accomplish the same thing by backing your FL die back up 3/4 turn off the shell holder. IOW, raise the ram, screw the die down till it hits, lower the ram and unscrew the die 3/4 turn. That would size about 3/4 of the neck and leave 1/4 of the neck fire formed size. And it would do it without all that work hardening of the brass. It is a common practice and is call "Partial Neck Sizing" with a FL die. Sooner or later you would wind up with a crush fit at the shoulder and need to push it back and IMO sizing of the case body is beneficial to keep the case body from influencing the centering of the case in the chamber.
The difference between a typical 30 caliber expander of .306" and a typical 7mm expander of .282" is .016" and that would be a lot of expansion and sizing down and would be of no benefit that I could see.
So if you expand the neck with a 30 caliber expander and then start sizing it with a 7mm FL die, are you using the 7mm expander during this resizing?
If you are then you could accomplish the same thing by backing your FL die back up 3/4 turn off the shell holder. IOW, raise the ram, screw the die down till it hits, lower the ram and unscrew the die 3/4 turn. That would size about 3/4 of the neck and leave 1/4 of the neck fire formed size. And it would do it without all that work hardening of the brass. It is a common practice and is call "Partial Neck Sizing" with a FL die. Sooner or later you would wind up with a crush fit at the shoulder and need to push it back and IMO sizing of the case body is beneficial to keep the case body from influencing the centering of the case in the chamber.
The difference between a typical 30 caliber expander of .306" and a typical 7mm expander of .282" is .016" and that would be a lot of expansion and sizing down and would be of no benefit that I could see.
Autorotate19
Well-Known Member
Thanks,
Yes, I am using the expander ball. I used this method just to set my die correctly to bump the shoulder. I dont do it with every case. Just one to find the right setting. Im sorry but Im having a hard time understanding what you mean. After setting the die using the .30cal case, I put a normal fireformed 7mm case in the die and go the donut about 3/4 of the way down. I had a slight crush fit, just a little resistence shutting the bolt. Am I on the right track?
By the way my fired cases fit fine in my chamber with out any crush fit. Thats why he told me to try this and he said it had worked for him for 30 years.....
Yes, I am using the expander ball. I used this method just to set my die correctly to bump the shoulder. I dont do it with every case. Just one to find the right setting. Im sorry but Im having a hard time understanding what you mean. After setting the die using the .30cal case, I put a normal fireformed 7mm case in the die and go the donut about 3/4 of the way down. I had a slight crush fit, just a little resistence shutting the bolt. Am I on the right track?
By the way my fired cases fit fine in my chamber with out any crush fit. Thats why he told me to try this and he said it had worked for him for 30 years.....
Autorotate19
Well-Known Member
Okay, I read your post about 10 times and I think I get what your saying. If I partial neck size with my fl die eventually I will get a crush fit and then need to bump the shoulder back, right?
woods
Well-Known Member
There is a little contradictory statements in your posts. In your first post
"run my 7mm case through a .30 cal expander ball. "
in your last post
"After setting the die using the .30cal case, "
it made it seem like you were putting the 30 cal expander ball in your 7mm FL die, but then you seem to be setting your 7mm FL die using a 30 caliber case. So I'm a little confused about your process.
"run my 7mm case through a .30 cal expander ball. "
in your last post
"After setting the die using the .30cal case, "
it made it seem like you were putting the 30 cal expander ball in your 7mm FL die, but then you seem to be setting your 7mm FL die using a 30 caliber case. So I'm a little confused about your process.
Autorotate19
Well-Known Member
Okay sorry, I take a fire formed 7mm rem mag case, I put it in a 300rum fl die and I just run the case far enough in to size the neck to .30 cal. Then take it and run it in my full length 7mm rem mag die with the 7mm expander ball installed. The die is backed up off of the case holder a full turn. I keep screwing the die in as I size down the case. I did this until I get a slight crush fit in my gun. Set the die there, then put a normal fired formed 7mm case in the die and got the donut. Sorry its hard to explain. Get it?
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woods
Well-Known Member
Better. If you are running a .306" or so expander ball into the neck of a fire formed 7mm which should be ~.288", then the difference is .018" or so. That would mean your case neck is now much larger than the chamber neck and wouldn't fit. So then you size the neck down with your 7mm die but only to a point where you get the crush fit.
Then you lock your die in and resize the rest. It would seem that the die setting would not leave much of the neck unsized (donut) and if it is adjusted too far down then you will start to size the case body. Sizing the case body would squeeze the case like a baloon and push the shoulder forward thus creating a crush fit.
Are you sure you are not creating the crush fit by starting to size the case body and pushing the shoulder forward rather than bumping against the unsized portion of the neck?
Lots of dynamics here
Then you lock your die in and resize the rest. It would seem that the die setting would not leave much of the neck unsized (donut) and if it is adjusted too far down then you will start to size the case body. Sizing the case body would squeeze the case like a baloon and push the shoulder forward thus creating a crush fit.
Are you sure you are not creating the crush fit by starting to size the case body and pushing the shoulder forward rather than bumping against the unsized portion of the neck?
Lots of dynamics here
Autorotate19
Well-Known Member
There is about ten thousands difference between the mouth of the case and the balloon. I can send you pics, whats your email? Thanks
