I have 100 .243AI lapua brass. As with most lapua and good redding bushing dies, my runout is pretty good. Around 70% .001 or less, around 25% .002 or so and then a few in the .003-.004 range (used for foulers). My question is, when I clean up all the brass and run even the 3-4 thou fired brass over the concentricity gauge, it shows good (.001 or so). At what point in the reloading process am I causing some to be .002+? Is it small differences in case neck thickness? The bullets themselves? Of course the cure is to simply fireform more brass and take the ones with the best runout, but I am just curious as to anyone else's opinion. Thanks
brass runout - before/after sizing
- Thread starter Benjerman08
- Start date
As you might have guessed, there are several schools of thought on this subject.
And its my belief, its all in the brass, once a runout case, always a runout case.
To prove this to your self, mark the high or low side of the neck on the cases with the most runout, using a permanent marker, it will stay on until your next sizing, just dont clean them to much. Then check the runout again, and see if the old and new marks are in the same place, or close to it. If they are, its in the brass, unless you somehow index the cases in the dies, and most dont.
I believe its in case wall thickness, from the neck mouth, down to the case head. The high side of the neck runout, will be the thick side of the case wall.
You may get other opinions on this subject.
Mike.
And its my belief, its all in the brass, once a runout case, always a runout case.
To prove this to your self, mark the high or low side of the neck on the cases with the most runout, using a permanent marker, it will stay on until your next sizing, just dont clean them to much. Then check the runout again, and see if the old and new marks are in the same place, or close to it. If they are, its in the brass, unless you somehow index the cases in the dies, and most dont.
I believe its in case wall thickness, from the neck mouth, down to the case head. The high side of the neck runout, will be the thick side of the case wall.
You may get other opinions on this subject.
Mike.
BoydAllen
Gold $$ Contributor
If you have a little research budget, and are curious, Size them with a Lee collet die, and then remove the bushing from your FL die, and use it as a body die, and let me know what results you get. As I understand it, the regular .243 Collet die will work, but call Lee to make sure. Also, in small tests that I have done of multi-step sizing, the order that the dies are used makes a difference. Do a few each way, body then neck vs. neck then body. I think that you will see what I mean.
I agree with MikeM.
The root cause of runout is case thickness variance. Sizing is the action that brings the problem to light. The more you size, the more you see it.
A collet die(at best), would help no more than neck turning does because thickness variance runs full length of brass. You cannot shortcut around the box-o-bananas you create by reloading brass that is not full length consistent in thickness.
And to solve the mystery above, you size the necks before the body for lowest runout. This is because brass is never straighter than pulled smoking from a chamber. Straight brass allows better centered neck sizing.
At what point in the reloading process are you causing additional runout?
Step one... Lack of brass measurement and culling prior to preps.
Additionally, pretty much anything you do with fireformed brass beyond it's extraction will bring out more and more runout. So do as little as possible to it.
The root cause of runout is case thickness variance. Sizing is the action that brings the problem to light. The more you size, the more you see it.
A collet die(at best), would help no more than neck turning does because thickness variance runs full length of brass. You cannot shortcut around the box-o-bananas you create by reloading brass that is not full length consistent in thickness.
And to solve the mystery above, you size the necks before the body for lowest runout. This is because brass is never straighter than pulled smoking from a chamber. Straight brass allows better centered neck sizing.
At what point in the reloading process are you causing additional runout?
Step one... Lack of brass measurement and culling prior to preps.
Additionally, pretty much anything you do with fireformed brass beyond it's extraction will bring out more and more runout. So do as little as possible to it.
Ben: I'm a firm believer in the school of thought that "all brass is not created equal". Future problems that show up when loading were created when a particular piece of brass was in the drawing stages, and when extreme, will remain there, forever. My "solution" is to identify the brass that exceeds my limits and use it accordingly, or if it's really bad, throw it away. Fortunately that extreme measure has never been required of the very $$$$ Lapua, only the "W" and "R" brands, which I seldom use anymore anyway. How else to explain 40 of so cases that are loaded, all using the same tools and components, and 4 or 5 may have excess R/O, while all the others are very good to excellent? Seems to me if it were a loading tool problem, they would all be bad. Just my thoughts. 
If you have a good chamber and the fired brass has a run out of .000 and you size it and it's still .000 then you seat the bullet and you have run out,it's the seater, if it happened in sizing,it's the sizing die.It can be traced to a operation,but if you have a factory chamber or untrued action very little can be done......jim
Thanks for the great replies. This forum is great. One can discuss those little nagging questions with others. Glad to hear someone say something about order of using the dies. A while back I was unsatisfied with my runout (I want .002 or better for long range) and while talking to the good people at Redding, they told me to neck size FIRST before body sizing/bumping (I have the 3 die set). I always thought that the pressures of body sizing would have thrown the neck out of alignment, but I was wrong. My runout improved when I started neck sizing first. Doesn't make any sense to me, but it works. And yes, I need to cull the few extreme cases. When we really think about it, it is amazing that one person can make some brass, another makes some dies and someone else makes a bullet and we can put it all together with .001 runout and sometimes less!
I've found that I can use Redding FL bushing dies, and keep my run-out at .001" about 95% of the time. I rarely get one with .002" run-out. I attribute the low run-out to resizing and pushing the shoulder back -.002" or less (measured) and by using the same die in one operation.
It's also important to use the correct bushing. It can't be too tight.
- Innovative
It's also important to use the correct bushing. It can't be too tight.
- Innovative
Mikem said:
I have quoted my own post, to make it easy to refresh memories. Or in case you haven't read them all.
I would like someone to explain why this happens, if the problem is not in the brass. I know for a fact this occurs, I have tried it on thousands of round (all Lapua 6BR brass) bushing neck sized.
Example: If you have a case, that after all reloading is done, has, .006 runout. It will go back close to .000 after firing. But it will again have runout after its reloaded the next time. With the kicker being, its High (or Low) side will always be, at or close to, the same side of the case neck.
If you dont believe this, try it yourself.
Mike.
Mike, you are correct that a case with excessive case body thickness variance will show more neck thickness variance and will generally have more concentricity runout. The case thickness can be measured and marked, see this article I wrote some months ago:
http://riflemansjournal.blogspot.com/2009/07/reloading-audette-neco-case-checker.html
Having said that, if you turn the necks and use dies appropriately (right bushing sizes, sequencing, O-rings) you can make the most of what you've got. I just wrote another little article about that:
http://riflemansjournal.blogspot.com/2010/04/reloading-two-step-sizing-and.html
Hope this helps.
http://riflemansjournal.blogspot.com/2009/07/reloading-audette-neco-case-checker.html
Having said that, if you turn the necks and use dies appropriately (right bushing sizes, sequencing, O-rings) you can make the most of what you've got. I just wrote another little article about that:
http://riflemansjournal.blogspot.com/2010/04/reloading-two-step-sizing-and.html
Hope this helps.
limbic,
Like the above posts have alluded to, including German's article, neck sizing first seems to give the least runout and best results for most. Then body/bump.
Like the above posts have alluded to, including German's article, neck sizing first seems to give the least runout and best results for most. Then body/bump.
Mikem said:
It seems to me that 55Kpsi+ combined with barrel steel's yield results in an ideal sizing operation. There is less rolling of brass, as typical with insertion sizing in a die.
But the case will not continue(through many cycles) coming out with low runout, if it has alot of thickness variance.
The thicker side will springback more, and yes this will occur where it's thicker -everytime.
One thing consistently implied on shooting forums is that use of Lapua brass alleviates the need for basic reloading measurements. Well, I'm certain those who perpetuate this lore have never measured brass of any sort.
Nothing wrong with Lapua(I love it), but across the gamut of cartridges, lot to lot, it is no better w/regard to thickness variance than other brands I've measured.
Another thing implied is that FL sizing makes straighter ammo than bushing neck dies. This is absolutely false.
Dies do not straighten ammo. They screw it up. The more they size, the more they screw it up.
The ONLY way to 'straighten' brass, if consistent, is fireforming.
Mikecr, Boy am i glade you told me that my FL. dies are junk when thy load .000 to .001 all the time in 6.5x47,dasher and 7mm08. The bushing die are now retired with the bushings removed to do depriming only because of run out. The FL.dies were sent back and the necks honed to my specs. and the shoulder sizes .002 or less and the base .001.
The bushing dies had been sent back to the factory because of over sizing and i was told they were with in specs. So to make a statement that FL. die are bad is false.......
You are right about the FF. i run the cases through a concentricity gage on each operation, FF,sizing and bullet seating that will tell the story. The only good die it the one that loads .000 to .001.........jim
The bushing dies had been sent back to the factory because of over sizing and i was told they were with in specs. So to make a statement that FL. die are bad is false.......
You are right about the FF. i run the cases through a concentricity gage on each operation, FF,sizing and bullet seating that will tell the story. The only good die it the one that loads .000 to .001.........jim
ANother great topic close to my heart guys
Seems like we have two similar threads running at once but to try and combine some experience on the original topic here (shell problems and runout) and point people also to the other thread currently running by German as well (dealing more with the dies).
Each individual case seems to vary in runout for several reasons I will list them in order of importance in my eyes (and I may be wrong here so chime in with your experience please: 1) Primarily variations in Neck wall thickness as explained here by many but also 2) uneven mouths to the shell - it is also important to have a square mouth with nice chamfer on both outside and inside of shell to ensure feeding into the dies and projectile evenly. 3) Thirdly variations in neck wall hardness (less important as the first). Even after turning necks and chamfering evenly you can still see a few problem shells. It is my experience that a trip through the annealing process again can sort this out.
Perhaps as suggested the easiest way out is to buy lots of shells, fireform them then neck size - then sort by runout as described.
Cases are one thing but dies, and the order you use them are also very important (see Germans post).
Mikecr - I have a process for straightening my bad shells that works very well (and uses a FL die) but agree generally in principal for off the shelf FL dies - they tend to oversize the neck and then pulling the expander ball back out too far makes for a huge error. Try removing the expander ball and running a "bad shell through the die in three or four rotated positions n the shell holder (this is a lot of work on the brass but can be "straight - just with too small a neck size). If you like what you see you can then get the neck ground out so there is less work for expander to do.
My Step By step process to sraighten shells: 1) I take a shell with excessive runout (e.g. 7 thou), 2) Expand the neck with tapered expander mandrel (home made but you could use the ones sold for neck sizing dies) to a size above that of the actual caliber (e.g.270 for 264 cal.) 3) then neck turn the shell for minimum neck wall thickness variation. 4) Next I put it back through the modified FL die (reamed out in neck to your preferred neck tension with no expander ball or expander ball that is barely doing anything). I then rotate shell 1/4 turn and put through again and repeat. This is a lot of work but produces a shell with almost zero (less than 0.5 thou) runout in almost all cases.
Final problem is you have a shell that has had a lot of work so is quite brittle in the brass - 5) Annealling should be carried out. Follwed by trimming and chamfering. These shells tend to work much better from then on. A lot of work and probably easier to ditch the shells - but I like doing this sort of thing.
Of course you are left with FL sized shell which although straight, needs to be fireformed again unless you have a FL custom die to match your chamber like Jims. I grind/hone out my own and get good results (like Jim) too, but a properly set up neck die can work just as accurately - see Germans thread again.
OOOOHHH - it never ends!!!
Great thread - keep it up, keep it happy!!
cheers, CAM
Seems like we have two similar threads running at once but to try and combine some experience on the original topic here (shell problems and runout) and point people also to the other thread currently running by German as well (dealing more with the dies).
Each individual case seems to vary in runout for several reasons I will list them in order of importance in my eyes (and I may be wrong here so chime in with your experience please: 1) Primarily variations in Neck wall thickness as explained here by many but also 2) uneven mouths to the shell - it is also important to have a square mouth with nice chamfer on both outside and inside of shell to ensure feeding into the dies and projectile evenly. 3) Thirdly variations in neck wall hardness (less important as the first). Even after turning necks and chamfering evenly you can still see a few problem shells. It is my experience that a trip through the annealing process again can sort this out.
Perhaps as suggested the easiest way out is to buy lots of shells, fireform them then neck size - then sort by runout as described.
Cases are one thing but dies, and the order you use them are also very important (see Germans post).
Mikecr - I have a process for straightening my bad shells that works very well (and uses a FL die) but agree generally in principal for off the shelf FL dies - they tend to oversize the neck and then pulling the expander ball back out too far makes for a huge error. Try removing the expander ball and running a "bad shell through the die in three or four rotated positions n the shell holder (this is a lot of work on the brass but can be "straight - just with too small a neck size). If you like what you see you can then get the neck ground out so there is less work for expander to do.
My Step By step process to sraighten shells: 1) I take a shell with excessive runout (e.g. 7 thou), 2) Expand the neck with tapered expander mandrel (home made but you could use the ones sold for neck sizing dies) to a size above that of the actual caliber (e.g.270 for 264 cal.) 3) then neck turn the shell for minimum neck wall thickness variation. 4) Next I put it back through the modified FL die (reamed out in neck to your preferred neck tension with no expander ball or expander ball that is barely doing anything). I then rotate shell 1/4 turn and put through again and repeat. This is a lot of work but produces a shell with almost zero (less than 0.5 thou) runout in almost all cases.
Final problem is you have a shell that has had a lot of work so is quite brittle in the brass - 5) Annealling should be carried out. Follwed by trimming and chamfering. These shells tend to work much better from then on. A lot of work and probably easier to ditch the shells - but I like doing this sort of thing.
Of course you are left with FL sized shell which although straight, needs to be fireformed again unless you have a FL custom die to match your chamber like Jims. I grind/hone out my own and get good results (like Jim) too, but a properly set up neck die can work just as accurately - see Germans thread again.
OOOOHHH - it never ends!!!
Great thread - keep it up, keep it happy!!
cheers, CAM
BoydAllen
Gold $$ Contributor
In my experience, the straightest FL sized brass comes from a die that is a perfect match for the chamber and the brass. The easiest, and cheapest way to arrive at this situation ,for a tight necked chamber, is to pull the decapping stem from a standard FL die, size some work hardened cases, and design a chamber to fit the sized brass. I have done this for myself and friends a half a dozen times, so I know it works. As it turns out, it is easier to fit a reamer to sized brass than a die to a chamber. The fly in the ointment for the latter is that you don't know exactly how much brass springback to allow for, or dimensional change from heat treat. Doing it my way, the reamer is ground to fit brass that has already sprung...so to speak. Also, reamer plus standard die costs considerably less than reamer plus custom die.
Boyd, I always turn necks, I always use FL. dies. one die and it's always the same,neck tension is set to my specs. from Forster for $14.70. when you turn necks you can toss the expander ball, if you chose not to turn necks the lumps and bumps are transfered to the outside of the neck.
I find great pleasure in trying to make them as perfect as i can and understand that XC shooters have different standard than benchrest shooters but it's a different game, I use to do that age took that away,so now i set them on a bench and i set on a stool............jim
I find great pleasure in trying to make them as perfect as i can and understand that XC shooters have different standard than benchrest shooters but it's a different game, I use to do that age took that away,so now i set them on a bench and i set on a stool............jim
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