Runout issues with Redding Comp Bushing die

Discussion in 'Reloading' started by AtownBcat, Aug 11, 2010.

  1. AtownBcat

    AtownBcat Well-Known Member

    Feb 3, 2009
    I had 50 rounds of RWS brass once fired. I checked the runout of the empty cases on my RCBS Case Master and all 50 rounds measured no more than .001 runout. When I ran them through the redding bushing die(with .332 or .331 ) the very best were .0025 with the worst being .006. Im still a novice reloader but I can only come up with two possible issues. 1 either the cases have .0025-.006 difference in neck thicknesses or the die is causing a problem. The rws has a great rep for being second only to lapua as far a quality so i think it is the die. I have removed the expander ball. the fired case measures .340 the sized case measures .331 to .330, is this to much in one step? Any ideas?
  2. Gene

    Gene Well-Known Member

    Jan 23, 2007
    Expander balls often cause high run out, keep it out. It is not unusual for new virgin brass to measure low run out and reloads to increase it. Zero run out is impossible; I don't worry about until it goes over .003" and some competitive shooters pay no attention to it at all. Try skim neck turning those cases slightly. Are you measuring on the unfired case neck or on the bullet ogive after the round is loaded?

  3. AtownBcat

    AtownBcat Well-Known Member

    Feb 3, 2009
    Hey Gene, thanks for the reply. The brass that has almost no runout is actually not vergin brass, but once fired. To answer your other question I'm measuring the runout before the bullet is seated, so its just an empty case.
  4. boomtube

    boomtube Well-Known Member

    Oct 8, 2007
    Two things.

    No matter how straight the outside of a neck is, what counts is how well the inside matches the outside. That's why many of us skim turn the outside of our necks, it provides for more cosistant thickness and better alignment.

    Bushing dies aren't the magic cure-all for concentricity some seem to think they are. Lee's collet neck sizers are perhaps the best neck dies for factory chambers.

    Expanders can easily pull a straight neck out of alignment and the greater the difference between the sized inner diameter and the expander diameter is, the more probalble some neck bending will occur. That's why it's best to obtain a bushing that's as close to the expanded outside diameter you want as possible. It's great if your expander just barely rubs the necks on the way out.

    It appears that some folks "measure" neck runout improperly and have much more of it than they realize. And some don't seem to understand that the Total Indicated Runout (TIR) is twice the acutal runout so their's seems worse than it actually is. Seating a bullet just magnifies whatever runout problems the necks already have.

    It's not impossible to get basically "zero" runout on individual rounds but it's very hard to get zero on an entire run. That requires perfect cases, perfect dies and perfect work methods. And a lot of good but not perfect cases get culled. (Nothing has absolute zero runout if we measure to enough decimal places, but anything under 1 thou TIR is an effective zero.)
    Last edited: Aug 11, 2010
  5. Boss Hoss

    Boss Hoss Well-Known Member

    Nov 10, 2005
    This may help you in the future. My Smith Speedy Gonzales (on his way down from Colorado right now to visit his newest grandson also bringing my newest competition rifle!!) wrote this and is an excerpt from his lengthy “Benchrest Primer Article”. Read, Learn and become a better shooter----this is valuable assuming your rifle is capable of benefiting from this level of precision preparation:


    For those familiar with reloading this particular Full Length (F.L.) size die is nearly identical to what you have used in the past, with one exception. The neck portion of the die has been machined away to allow the introduction of a neck sizing bushing. This allows for bushing of different diameters to be used to either loosen or tighten the neck tension on the bullet. The expander ball is also done away with, since the need to undersize the neck and then pull the expander through it to allow a bullet to again go into the neck is done away with.

    The old myth that neck sizing produces the best accuracy, has proven to be just that. Tony Boyer has 98 Benchrest Hall of Fame points, nearly twice as many as the gentleman in second place. All of these points were garnered while using the full length/bushing type size die. Another feature of the custom FL / Bushing type die is the fact that most are machined using matching reamers to the chambers in the rifles the dies are built for.


    The custom benchrest reloading press was designed with two things in mind. One was to build a high quality product with as tight a dimensional tolerance as could be held and still have the parts move.

    The other requirement was for the press to be compact, light and portable. Once these criteria had been met, the competitor now has the ability to begin the procedure of building some of the highest quality ammo in the world.

    This press, coupled with the full length / bushing die, set the shooter at the leading edge of reloading technology.


    A trait most newcomers to the sport of benchrest are surprised to see is the simplicity of most of the reloading tools used by most of the benchrest shooters. Most expect to see spring-loaded doodads and digital gadgets in the hands of men with thick glasses and white lab coats. Fortunately, this is not the case, as the K.I.S.S. principle is kept firmly in mind. K.I.S.S., "Keep It Simple Stupid." This principle is the root of most benchrest technology. While many of the parts you will see in this sport outwardly appear to be very complex and difficult to use, they turn out to be some of the most basic of machines.

    The straight-line bullet seater die is no exception. The die is chambered with the exact same reamer as the chamber in your rifle. This ensures the competitor that when the bullet is seated into a sized, charged and primed case, it will be in as perfect alignment with the corresponding chamber in his/her rifle as possible. (For instructions on the proper use of this type of die, see our "Accuracy Tips" section).


    The benchrest version of the arbor press is quite small compared to some of their larger industrial brethren, yet its function in the chain of loading supremely accurate ammo cannot be played down due to its relative size.

    It is used mainly in the process of giving the benchrest reloader the needed mechanical advantage when seating his/her bullets into the case necks. Due to its size, the arbor allows the reloader to actually feel the bullet as it enters the case mouth and feel slight variation in looseness or tightness of the neck on the bullet. This allows the reloader to possibly cull a bad round out of his block before shooting it at the target to ruin a winning group.


    Along with the major tools mentioned, there is a subset of support tools required to load match cartridges. These include the following:

    Loading Block - Typically a small machined piece of plexi-glass, wood or Delrin. Its purpose is to hold 20 to 25 cartridges in place as the loading process takes place.

    Case Neck Brush - The case neck brush is designed to remove carbon build up inside the neck. The brushes are usually made from hard nylon or bronze. Some argue the nylon is best for the job because the bronze brushes tend to shed their bristles as they become worn. Iosso has just introduced a new heavy bristle nylon brush to the market that may prove to be the best of both worlds.

    Primer Flipper - This is a very handy tool. It has the ability to orient all of your primers in one direction at one time. This will greatly improve your speed by eliminating the need to orient each primer by hand as they are seated into the case.

    Primer Seater - Manufactured by several companies, the basic tool designs are nearly identical. The purpose of the benchrest primer seater is to hold the case squarely against the shell holder and seat a primer to a uniform depth below the head of the case. It accomplishes this task through its use of a two piece sleeved ram. As the handle is squeezed, the spring loaded outer sleeve comes into contact with the head of the case and pushes it square with the inside lip of the shell holder. As the operator continues to squeeze the handle, the inner ram pushes the primer into the case head until it is seated correctly.

    Neck Sizing Bushing - These are graduated rings of case-hardened steel or carbide used to resize the necks of fired cartridges. They are used in conjunction with the "custom full length / bushing size die" to allow the shooter to fine tune the grip case neck on the bullet of the loaded round. The standard formula for determining the correct bushing diameter is as follows: (bullet diameter) + neck wall thickness per side x 2) - (0.0030 std. minimal neck size reduction) = standard nominal neck bushing size or:

    Bullet Diameter 0.2430

    Wall Thickness x 2 + 0.0200

    0.0030 Std. minimal neck size reduction - 0.0030

    Standard nominal neck bushing size = 0.2600

    Loading Table - While many ranges offer facilities from which to load and clean, it is sometimes better to carry your own loading table. This enables the shooter to begin a program that promotes a consistent methodology of procedures. Once the shooter begins to setup his equipment in a consistent manner, it will soon become second nature and much more of the focus can be channeled to the task of shooting tiny groups. Most loading tables are made by the competitors themselves. Legs can be purchased from any local hardware store as well as the plywood top. A common table dimension is 2 ft. x 4 ft. x ¾ to 1 inch thick.


    The pinnacle of modern ammunition is the loaded benchrest cartridge. No other shooting sports fraternity on Earth employs the attention to detail and the painstaking assembly procedures as those who compete in the world of benchrest.

    The benchrest round when broken down is comprised of four basic components: the case, the bullet, the primer and the powder. What makes these four components so different from normal ammunition are the tolerances to which they are held.

    The Case - When the competitor pulls the trigger and the firing pin slams into the primer, initiating the chain of events that will propel the projectile on its path to the target, the only reusable component remaining is the case. Because of its resilience, the brass (in benchrest terminology "The Brass" is the nomenclature used to describe the case) and its ability to be reloaded repeatedly, is pampered and treated with kid gloves. It is actually possible to completely wear a barrel out (approximate match barrel life is 1500 rounds) with 20 pieces of brass loaded over and over again. This translates to each case being reloaded 75 times each.

    In benchrest shooting, the reigning king of cases is the 6PPC. The PPC is based on the Lapua 220 Russian case, co-developed by Ferris Pindell and Dr. Lou Palmisano. Since Since its inception in the mid 1970s, the PPC has yet to be rivaled in the field of pure accuracy potential. Its short fat design, coupled with an almost perfect case capacity to bore diameter ratio, make it one of the most efficient cases seen in the last 30 years. The 30-degree sharp-shouldered piece of brass provides a nearly perfect 100% powder loading density.

    The H.P. White Testing Laboratories accredited the features of the PPC to be the determining factors for the most uniform ignition, burn rate and pressure curves ever demonstrated in their facilities. Look for brass preparation techniques in the "Accuracy Tips" section.

    The Bullet - No other component in the sport of benchrest has been as scrutinized as the bullet. For it is the bullets job to translate onto the target the shooters ability to perform his craft well.

    There is no commercial bullet to date that is capable of delivering the consistent accuracy needed to be competitive in the sport of benchrest. All benchrest bullets are made by hand, on a custom basis, with very limited production quantities. One of two bullet forms are currently seen on the firing line of today's benchrest shooting events. The first, and probably most common, is known as a "Rorschach" shape. This is a bullet with a straight cylindrical body and a segment of a circle forming the point or "OGIVE". This bullet form is relatively easy to tune but can become very wind sensitive.

    The second bullet form is what Speedy Gonzalez coined the "DOUBLE-RADIUS" bullet. This type of bullet has no straight cylindrical section to the body whatsoever. The 2R bullet form is actually two arcs from large radius circles becoming tangent to one another creating the bullets shape. When measured from the base, these bullets have a constant taper and the tangent point where body and ogive meet is virtually impossible to measure without the use of a CMM (coordinate measuring machine). Higher velocities and better wind bucking capabilities are attributed to this type of bullet form. The benchrest reloader is urged to try both types of bullet forms in every new barrel.

    Accuracy Powders - Present day smokeless propellants are classified into two groups, single base and double base. They are both primarily formulated from nitro-cellulose with the addition of nitro-glycerin to the double base for a higher energy yield.

    These powders are then divided into two groups according to their physical shape, either spherical or extruded cylinder. The spherical or ball powders are said to be easier on the barrel because of their cooler burning rates. They also meter through a powder measure like water making them easy to use when reloading.

    The extruded powders are known for their ease of ignition. This is especially true in cold weather. As a competitor, it is to your advantage to be aware of these characteristics thus providing yourself with a better-rounded loading program. The ability to have an adaptive loading program is one of the secrets of the top-level shooters in this country.

    The Primer - Once considered insignificant in the equation of accuracy, the primer has now fallen under the microscope. No longer are these components, which costs less then $0.03 each, taken for granted. Benchrest shooters are now taking the time to check different lot numbers of the same brand as well as different manufacturers in an effort to wring the last bit of group shrinking magic out of their components. Primer selection and testing will be discussed in the "Accuracy Tips" section of the manual.
  6. Mikecr

    Mikecr Well-Known Member

    Aug 10, 2003
    Yes, it's too much sizing for a single bushing.
    .340 fired, means the chamber neck was atleast .342 with springback, and that is pretty sloppy for a 308. Well, maybe not for something tactical..
    Also, never assume anything, about anything. Measure your brass thickness for it's variance.
    All the oversizing sizing you're doing here is amplifying thickness variance. The same happens to the body of cases with alot of thickness variance, that are heavily full length sized. Runaway runout...

    This brings up another point:
    You cannot just halve your TIR!
    Runout is not concentricity..
    Runout is just what it is, and total rounout is just that. TOTAL..

    TIR is the result of more than just one offset, and can be independent of centerline. It is the sum of offsets and measurement error.
    With this, it cannot be assumed that your necks are 'not centered' if you have thickness variance, or the cases aren't straight, or the case heads(taken as a datum) are not square, or the bullets aren't seated straight. These potential offsets and errors combine to produce what you have(not half of it).

    It is not always easy to measure offsets individually. But you can recognize the worst in your system's results, and do alot of things to improve it.
  7. AtownBcat

    AtownBcat Well-Known Member

    Feb 3, 2009
    Boss: that is alot of good info. I have copied and pasted it so that i can print it out.

    Mike: some of what you say is quite frankly over my head. I ran my empty cases through a redding body die and this did not produce any runout...or am i reading concentricity?

    I took 10 of thoes case and used my lee collet die and only had a it might just be that im trying to size two small with one step like you said.

    my barrel is a kreiger and the chamber was cut with a sammi speck reamer so it could be a little one the "sloppy" side..but doesnt the fact that the cases come out with almost no runout mean that my chamber is true?
  8. TOM H

    TOM H Well-Known Member

    Dec 24, 2001
    I'm using a Wilson arbor neck die my fired cases neck dia .340 and I use a .330 bushing and have no problem.

    Here something from Redding
    Lube case necks, even with TiN coated bushings.
    Partial size case necks. Sizing 1/2 or 3/4 of the neck seems to be the most popular.
    Try flipping the bushing over. We like to install them with the letters down to start with.
    Trim cases mouths square so they will enter the bushing straight. Don't forget to chamfer the case mouth, inside and out. This is very important as it eases the entry of the case mouth into the bushing, and the bullet into the case mouth.

    I couldn't pull it up but they include standard expander also a small one that hold the decapping pin and I'd use that one and that might help. If you didn't get one call them.
  9. Mikecr

    Mikecr Well-Known Member

    Aug 10, 2003
    That's a good thing, & normal.

    When you exceed ~5thou of sizing with a bushing, you abruptly force brass inward at angles exceeding the desired set. It'll springback typical, but stressed all to hell.. This stress varies with thickness/variance.
    FL, or non bushing neck dies, are typically less abrupt because many cartridge necks & chambers have a bit of taper from shoulders to mouths by design.

    Yes, and I'm not even sure how some gunsmiths manage to cut chambers that aren't round. It is normal for runout to be lowest right out of a smoking chamber. Afterall, firing in your chamber amounts to your best sizing operation. Further actions can only screw things up from there. So it's best to limit further actions to minimal.
    With a chamber neck so over sized as yours, I would not bother with a bushing die. Use the collet die.

    Bushing dies are very versatile. But like anything else they have an optimum range to stick within.