I just installed a forester decapping unit in an rcbs die to try to reduce runout I believe that it is set up correct per forester instructions with the expander ball lower third lined up with the vent hole in the die , but I am still getting 4 to 5 thousandths of run out on most of the brass necks prior to seating a bullet . the fired brass before resizing is around 1 thousandth or less does anybody that uses this setup know what I may be doing wrong here ?
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forester decapping unit in rcbs die ?
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bigedp51
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If your getting that much neck runout the expander is not set high enough. The neck of the die should be holding and centering the case neck when the expander enters the neck. If you raise the expander too far you will feel too much resistance on the up and down stroke of the ram. Bottom line the longer the case neck is held and centered by the die the less chance of the expander pulling the neck off center.
I equipped all my RCBS dies with Forster expander and spindle assemblies. Below the original RCBS expander on the left is raised as far as it will go and the Forster expander is set at the correct hight.
I have also put them on my Redding dies but a rubber o-ring is needed under the lock ring to allow the spindle to float and self center.
When you have the expander set correctly your neck runout should be the same as your neck thickness variations. And on a turned neck it should be .001 or less.
I equipped all my RCBS dies with Forster expander and spindle assemblies. Below the original RCBS expander on the left is raised as far as it will go and the Forster expander is set at the correct hight.
I have also put them on my Redding dies but a rubber o-ring is needed under the lock ring to allow the spindle to float and self center.
When you have the expander set correctly your neck runout should be the same as your neck thickness variations. And on a turned neck it should be .001 or less.
Thank You, this is exactly the info I was looking for the bad part is I had already resized all my brass before thinking of posting this but I am feeling pretty good in that as I load these they are running pretty steady .004 loaded . before getting the forester stem I was getting some in the .010 range after seating a bullet but also as low as .002 resizing with the seating stem not locked down so it could self center , with this help I think I should be able to bring them all the same in the next resizing go around I will post results Thank you
CatShooter
Well-Known Member
I haven't tried that with this one but doesent that leave you with too much neck tension ? , I thought that I had a bunch of old 7 rem brass from the last one I had laying around to play with the dies setup with but everything I found was loaded or already resized , so ill have to fire this batch before I can work on it again
CatShooter
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bigedp51
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den
When you remove the expander and size a case it should be as straight and concentric as it ever will be. If you have case neck runout after sizing "without" the expander then its most likely a die problem. If you then reinstall the expander and have more neck runout then the expander is the problem. If your resized cases have low neck runout but after seating the bullet the "bullet" runout increases the seating die is the problem.
After sizing with the expander I check case neck wall thickness with a Redding Case Neck Concentricity Gauge. Then I check case neck runout and it should be close to your case neck thickness variations.
I like the Redding gauge because with one twist of the wrist you know the neck thickness variations. This gauge also tells you a great deal about the quality of the case. I have had .223 cases with over .009 neck thickness variations. These type cases are used as blasting ammo in my AR15 and the best cases are used in my Savage bolt action .223.
Bottom line what CatShooter is getting at is "where" does your runout start and that is where you fix the problem.
At German Salazars website "The Rifleman's Journal" he did a seating die test with a RCBS, Hornady, Redding, Vickerman and Wilson. The Redding competition seating die came in first place and even had the ability to correct neck runout. (the Forster benchrest seating die is the same type die)
Reloading: Seating Die Runout Seating Die Induced Runout - A Comparison
by Germán A. Salazar
"#1 - Redding Competition Seating Die (sliding sleeve type, threaded die)
The Redding, which I expected to finish high, did what I thought couldn't be done - it produced rounds with an average runout that was less than the average case neck runout of the brass used. In none of the ten rounds loaded did the Redding increase the runout; it either held exactly the same or it decreased. The Redding, with an Average Runout Change of -0.0003" is the winner. The negative sign, of course, indicates a reduction in runout.
#2 - Wilson
#3 - RCBS Standard Die
#4 - Vickerman and Hornady (tie) with an Average Runout Change of +0.0006", bring up the rear - very much to my surprise. These are very useful dies, however and let's keep some perspective, with an ARC of about half a thousandth, I wouldn't be concerned about using them for Highpower match loading. "
When you remove the expander and size a case it should be as straight and concentric as it ever will be. If you have case neck runout after sizing "without" the expander then its most likely a die problem. If you then reinstall the expander and have more neck runout then the expander is the problem. If your resized cases have low neck runout but after seating the bullet the "bullet" runout increases the seating die is the problem.
After sizing with the expander I check case neck wall thickness with a Redding Case Neck Concentricity Gauge. Then I check case neck runout and it should be close to your case neck thickness variations.
I like the Redding gauge because with one twist of the wrist you know the neck thickness variations. This gauge also tells you a great deal about the quality of the case. I have had .223 cases with over .009 neck thickness variations. These type cases are used as blasting ammo in my AR15 and the best cases are used in my Savage bolt action .223.
Bottom line what CatShooter is getting at is "where" does your runout start and that is where you fix the problem.
At German Salazars website "The Rifleman's Journal" he did a seating die test with a RCBS, Hornady, Redding, Vickerman and Wilson. The Redding competition seating die came in first place and even had the ability to correct neck runout. (the Forster benchrest seating die is the same type die)
Reloading: Seating Die Runout Seating Die Induced Runout - A Comparison
by Germán A. Salazar
"#1 - Redding Competition Seating Die (sliding sleeve type, threaded die)
The Redding, which I expected to finish high, did what I thought couldn't be done - it produced rounds with an average runout that was less than the average case neck runout of the brass used. In none of the ten rounds loaded did the Redding increase the runout; it either held exactly the same or it decreased. The Redding, with an Average Runout Change of -0.0003" is the winner. The negative sign, of course, indicates a reduction in runout.
#2 - Wilson
#3 - RCBS Standard Die
#4 - Vickerman and Hornady (tie) with an Average Runout Change of +0.0006", bring up the rear - very much to my surprise. These are very useful dies, however and let's keep some perspective, with an ARC of about half a thousandth, I wouldn't be concerned about using them for Highpower match loading. "
CatShooter
Well-Known Member
By the way, Den...
What make and calibre is your brass.
Whether it is Lapua, Norma, Winchester, or Hornady makes a world of difference!!!
What make and calibre is your brass.
Whether it is Lapua, Norma, Winchester, or Hornady makes a world of difference!!!
I realized after posting the reply that removing the expander suggestion from cat shooter could be to diagnose what s causing the runout and it was
lightbulb I am planning on annealing these after this what will be third time fired and most are loaded running .004 runout , the gun is a savage with a criterion light varmint barrel chambered in 7 rem, I started with new nosler brass I did no prep it grew about .017 on the shoulder the first firing with searching internet threads apparently this is about right for a belted magnum on the first ,the fired brass barely moves the needle on the Sinclair runout gauge , I am using a lee seating die and it does not seem to be causing any problems as the run out actually did seem to decrease a small amount after seating I do not think I have ever seen this usually it increases . bigedp51 I do have a Sinclair neck consentricity gauge and a 7mm pilot that I kind of quit messing with a few years back so I can and will check as described in your post , lots of good stuff here, Thank You
lightbulb I am planning on annealing these after this what will be third time fired and most are loaded running .004 runout , the gun is a savage with a criterion light varmint barrel chambered in 7 rem, I started with new nosler brass I did no prep it grew about .017 on the shoulder the first firing with searching internet threads apparently this is about right for a belted magnum on the first ,the fired brass barely moves the needle on the Sinclair runout gauge , I am using a lee seating die and it does not seem to be causing any problems as the run out actually did seem to decrease a small amount after seating I do not think I have ever seen this usually it increases . bigedp51 I do have a Sinclair neck consentricity gauge and a 7mm pilot that I kind of quit messing with a few years back so I can and will check as described in your post , lots of good stuff here, Thank You
CatShooter
Well-Known Member
I realized after posting the reply that removing the expander suggestion from cat shooter could be to diagnose what s causing the runout and it was
Den... do you have a 7mm Mauser, or a 7mm Express, or a 7mm Remington Magnum (it does make a difference)!!
When you are asking for help, P-L-E-A-S-E give accurate information.
OK...
" I did no prep it grew about .017 on the shoulder the first firing with searching internet threads apparently this is about right for a belted magnum on the first [firing].
On the first firing of a belted case, measuring the "shoulder growth"" is useless.
A standard beltless/rimless case (like a 30-06) will grow on the first firing (and subsequent firings) because the case walls stick to the chamber walls, and the case head is blown back to the bolt face.
So, if the shoulder is moved forward, that comes from the case stretching in front of the case head (the "web). The case is longer, and if you measure the case length (from head to mouth) it will be the same amount longer.
But the belted case is restrained by the belt, and the fitment in the little space in the rear of the chamber.
The most headspace (minimum case belt, maximum chamber belt space) you will see in well made rifles is less than 10-ish thou....
My 264 Win Mag has 6 thou of "headspace", but on the first firing, shoulder blows forward 32 thou, but the case length does not grow - they stay the same. After that, on subsequent firings and loadings, they do not grow at all.
You need to take control of your case growth and case life. Learn to adjust your dies so the cases don't grow.
it is a 7mm Remington magnum , you said with your .264 win mag on first firing the shoulder moves 32 thou this does make the base to case mouth longer than before firing correct ? my resized twice fired brass roughly the same amount that the shoulder moved forward longer than unfired new roughly new 2.482 twice fired resized 2.497 I have my dies set using the hornady tools to bump the shoulder very slightly
CatShooter
Well-Known Member
"... does [this] make the base to case mouth longer than before firing correct".
No.
If you have a standard, rimless cartridge, like a 30-06...
... take a SAAMI minimum case (2.0456"), and fire it in a maximum SAAMI chamber (2.0587"), there is over 13 thou of air space between the case head and the bolt face.
When you fire the cartridge, the primer forces the round forward and holds it there while the powder lights and pressure rises. The pressure will rise and eventually, the case body expands like a balloon and the brass sticks to the chamber walls. Then the pressure is high enough, the back of the case stretches the 13+ thou.
Not, the case shoulder is 13+ thou forward, and the whole case is 13+ longer, and the web is now thinner and the case is well on the way to a head separation.
With the rimless case, the more space there is in the chamber, the more the case will stretch.
With belted cases, it it the belt that limits how far the case can go forward in the chamber... if you have a SAAMI maximum belt (0.220") and a SAAMI minimum Chamber (0.220") and 1/4" of space in front of the shoulder, the shoulder will blow forward 1/4", but the case will not stretch at all.
In either case, if you oil the case before the first firing, the case walls cannot stick to the chamber walls, so the case slips back on firing, and does not stretch.
Then... if you adjust your FL or Forster "Bump" die to just lightly kiss the shoulder, the cases will not stretch.
For normal shooting (not short range bench) there should be just the slightest resistance when closing the bolt. And space in the loaded chamber will translate into case stretch when the round is fired.
Cases with 17 thou stretch are already on their way to hell.
My 264 Win Mag has 6 thou of "headspace", but on the first firing, shoulder blows forward 32 thou, but the case length does not grow - they stay the same. After that, on subsequent firings and loadings, they do not grow at all.
I am reading and re reading your posts some I think I have a pretty good grasp on some is a stretch for me but trying to get it , so as I read the above you would never have to trim the 264 win brass not even once ? I currently in my process have been using the lee case length gauge piloted trimmers I attempt to trim all my cartridges with one of these every reloading cycle since it has not touched the case mouth on these I was under the assumption that I was not having major case growth
I am reading and re reading your posts some I think I have a pretty good grasp on some is a stretch for me but trying to get it , so as I read the above you would never have to trim the 264 win brass not even once ? I currently in my process have been using the lee case length gauge piloted trimmers I attempt to trim all my cartridges with one of these every reloading cycle since it has not touched the case mouth on these I was under the assumption that I was not having major case growth
