How to select a Redding bushing

Redding Bushing Dies: How to Select the Proper Bushing

Looking for a simple explanation of why we use bushing dies, or how to select the proper bushing for your Redding Type S, or Redding Competition Neck Sizing die? Here’s my take on it.

The advantage a bushing die has over a standard die is the amount of stress placed on the case neck as it’s sized. A standard full-length sizing die is machined to size a case to standard dimensions, regardless of case thickness. As far as the main body of the case goes, that’s no big deal. Once it’s fired to fit the chamber, the main dimensions of the case don’t change much in a die, even a full-length non-custom die. The problem is the neck.

To accommodate a wide range of varying brass thickness from brand to brand, and end up providing an inside diameter that will securely grip a bullet, a standard die uses two steps. First, the case is forced into the neck portion of the die and sized down, then it’s pulled back over an expander to set the final diameter.

In order to work with cases that are relatively thin, the interior dimension of the neck portion of the die is on the small side of neck diameter specs. That can be tough on brass, especially if it’s thick brass, like Lapua. It tends to cause concentricity problems, hardening of the brass, and muzzle velocity inconsistencies.

The bushing die eliminates the second step, and allows us to size the outside diameter of the neck to precisely where we want it. I prefer and recommend the Redding Type S FL sizing die. Click HERE to see why.

What diameter should the neck be sized to? I’ve had consistent success with brass that is sized .001” to .003” smaller than the loaded round’s outside diameter. This is commonly known as neck tension.

I now aim for .001” neck tension when working up a load. It provides enough grip to securely hold a bullet, is easy on brass, and doesn’t induce runout on a sized neck. Some of my older recipes still use bushings that squeeze the necks .002” or .003”. They work well, too.

I’ve tested different tensions within the same load, and even neck-turned some 260 Remington brass to see what difference it made.

I’ve found that as long as I don’t go over .001” of neck tension disparity, I can’t measure the difference. For example, .001” to .002” doesn’t affect anything, but .001” to .003” does. Neck turning has made no difference. I sort new cases for .002” or less thickness runout, but don’t turn them as a rule. I’ve since tested that process on a 7 WSM and 300 WM with similar results.

I concluded that the overall thickness of the brass was more important than small thickness variations when choosing a bushing.

Redding Die Bushing

To determine which bushing to use, you need to know what brass you’re going to use and how thick it is.

This is important. Brass can vary as much as .003” across different brands of the same cartridge case. The difference in thickness between Lapua and Remington 260 Remington brass is .002”.

The easiest way to measure for a bushing is to load a bullet in the brass you’re using and measure the outside diameter with a digital caliper. Subtract .001 and order that number bushing. For example, if my loaded round’s neck diameter is .294”, I’ll order a .293 bushing.

Measuring Loaded Round Mitutoyo Caliper

If you don’t have a loaded round, you can measure the case neck thickness, multiply it by two, then add the bullet diameter. For the round we just measured, it would look like this:

Neck thickness= 0.015”
Bullet Diameter= 0.264”

Neck Thickness (x2) + Bullet Diameter = Loaded Round Diameter

0.015”(x2) + 0.264” = 0.294”

To get an accurate thickness value, a ball micrometer works best. You can use a caliper, but because you’re measuring a curved surface with a flat anvil, it won’t be accurate. Mine come out .0015-.002” thicker when using calipers.

Measuring Case Thickness Mitutoyo Ball Micrometer

For reference, here are some of the cartridges I loaded last year, the brass I used, and the Redding bushing number:
  • 260 Remington/ Remington brass/ .288 bushing
  • 260 Remington & 260 Terminator/ Lapua brass/ .293 bushing
  • 300 Winchester Magnum/ Winchester brass/ .333 bushing
  • 7 WSM/ Winchester brass/ .312 bushing
  • 338 Edge/ Remington brass/ .364 bushing

I’ve only had one Redding bushing not match the dimension it was marked for. It was off by .001”. I ordered another one of the same size that was spot on. There are tolerances in everything, I guess. Don’t try to measure the bushing with your internal caliper jaws—it’ll be inaccurate because of the radius. Just size a case with it and see where you end up. These numbers are all relative anyway, and results on target are the ultimate measurements!

Check out this short video demonstrating how to measure for the proper bushings:

Here are some other things I do and have learned while using Redding bushing dies:
  • I use the plain steel bushings and lube the cases with Hornady One-Shot Case Lube before sizing.
  • I remove the decapping rod and expander from the Type S dies. An expander IS NOT needed when using a bushing die.
  • Don’t get wrapped around the axle about the exact amount of neck tension. Pick a value between .001” and .003” and run with it.
  • I’ve tried the bushings number up, and number down in the die. I insert the bushings with the numerical marking facing up. That makes it easy to look down in the die with a light to check which one is in it.
  • I clean my sizing dies before starting a big batch. I squirt a little One-Shot into the clean die before the first case gets sized, then leave it alone.
  • Keep notes on all bushing/die/brass combinations used, and always check the bushing number before sizing.
  • A Redding bushing die will not size the entire neck. Because of how the die is machined, it’s impossible. There will be a portion of the neck close to the shoulder that never gets sized. It’s normal. I set mine up so the bushing just barely self-centers in the die before locking the nut down.
  • Brass thickness dimensions vary from brand to brand, but calibers stay the same. If you’re using Lapua brass, you can use one bushing for 260 Remington, 6.5 Creedmoor, and 6.5-284.
  • I’ve ordered most of my bushings from Sinclair or Midway.
I think that’s all I have to say about using Redding bushing dies and choosing the proper bushing. As usual, I probably missed something important. Send me an email if you find something or have a question. Remember, results on target are all that matter to me. This is how I do it, but I won’t hold it against someone who does it differently. Question everything and try different methods until you get the results you want!


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As an Idaho native, avid hunter, and long range shooter, Sam has written numerous articles and gear reviews for various online publications. Specializing in long range hunting in the mountains of northern Idaho, Sam founded Panhandle Precision as a way to continue sharing his passions.

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  • Todd B
    January 29, 2017 at 16:25

    At this time I use the Redding neck bushing die approach on the 260 Rem only. It sure reduces the amount of work being done to the brass and lets us use the brass longer (neck/shoulder annealing is an important factor too)

    One thing I wanted to mention that I had to go through for my situation is to neck size down in two steps. Apparently my chamber is a little on the larger side in the neck area so when the cartridge is fired the neck diameter opens up to fill the space. Then when I use the neck sizing bushing I think I need, it reduce the neck diameter more than the bushing size. If I do a two step approach and only reduce the neck diameter 0.002 to 0.003 at a time then the neck diameter ends up right where I want it.

  • Brandon
    May 11, 2017 at 10:30

    Another excellent article! I have reloaded ammo for 12 years and I have learned a lot from your articles and your youtube videos. I have Redding bushing dies for my 20 Tactical and they produce accurate ammo. I have adopted some of your reloading techniques and will be buying Redding Match S Bushing dies for my 223 and 243 Remington 700 bolt action rifles.

  • Darwin
    July 2, 2017 at 06:28

    I was very pleased to find your youtube videos – they are the best I have seen period. Full of how-to info plus insights from a very experienced shooter/reloader. CC is an added bonus. I have reloaded for several years (but still a novice in many ways) starting with handgun ammo and now spend most of my time trying to find the right combo for my 22-250. I shoot targets @ 100 yds and am seeking the elusive bug hole. I am still a little confused about the sequence you follow for reloading – I don’t see if/when you neck size other than with a fl die is used. You use fl each time for hunting rounds but what about for target shooting. If you could list the steps and the equipment you use for each, I think many of us would benefit. If you have covered this previously in a video or you website, then I haven’t looked hard enough and apologize. Thanks.

  • David Swoboda
    February 8, 2018 at 14:34

    Thanks for all the information you share on your site! I live not far from you, just down the road in Post Falls, Idaho. In one of your articles, you talk about squaring up the dies in the press to help with concentricity issues. I’ve been chasing down potentially different causes of non-concentric rounds (now using Redding Type S dies) and squaring the dies in the press is something I’m not quite sure how to do. Any recommendations on how to solve this?

    • Sam
      Sam Millard
      February 8, 2018 at 15:04

      I use a small chunk of tool steel as a shim to force the bottom of the die parallel to the top of the shellholder. Just set the die up for the bump you want, and finger tighten the locknut. Then put the shim between the die and shellholder, apply pressure with the ram, and tighten the locknut. If the die and shellholder are square, the case should come out square. Any perfectly flat piece of steel should work. I’ve only had one die that didn’t square up, but the ammo shot as well as anything else I put together!

      • David Swoboda
        February 8, 2018 at 15:35

        Thanks for your speedy reply! Where can tool steel like this be found?

        • Sam
          Sam Millard
          February 8, 2018 at 20:32

          I got mine from a friend who used to work in a machine shop. I would look at machine shops, metal shops, or online. Another thing that would probably work fine is a plain steel ruler.

          • Todd B
            February 9, 2018 at 08:03

            If you have access to an old disk drive take one of the disks out and use it for a precision shim. The thickness is very parallel.

          • Sam
            Sam Millard
            February 9, 2018 at 12:29

            Good info. Thanks!

  • Mike
    February 10, 2018 at 10:19

    I have read about using expander mandrels to smooth out the inside of the case neck after running it through the bushing die. Do you an expander mandrel since the expander ball was removed?

    • Sam
      Sam Millard
      February 10, 2018 at 10:44

      I don’t use anything on the inside of the neck after sizing with a bushing die.

  • Dennis D
    June 23, 2019 at 08:39

    Hi Sam. I am increasingly becoming a huge fan of your written and video articles since finding your link online. I have been reloading for many, many years but just now getting into precision reloading. I recently built a 224 Valkyrie with Shilen Super Match barrel on an AR15 platform. Plan on shooting precision steel matches at some point in the near future. Don’t know if you do gas guns but was wondering if you could weigh in on standard vs. bushing dies for these. Not sure if the neck tension should be more on a gas gun because of the slamming effect of the BCG or not. I have the Redding Premium die set but would probably have gone with bushing had I seen your articles before hand. I did purchase an ELD stem for the seating die as I intend to use Sierra 90gr. Match King and Hornady 88gr. ELD.

  • Vf
    August 24, 2019 at 11:32

    Which is better for Idaho hunting? Panhandle up by Priest Lake or Snake river plains section of the state?

    • Sam
      Sam Millard
      August 25, 2019 at 17:45

      I don’t know. I don’t hunt in either area.

  • Peter Muscio
    September 27, 2019 at 23:29

    Sam, thanks for the no bullshit approach. I like it. I am new to reloading and have read and wathched heaps of stuff in reation to reloading. I like the term, if the effort doesn’t give results why do it and I think you have enough expirence to give an opinion. I enjoy your channel.

  • Sean
    November 26, 2019 at 17:24

    To clarify on whether to use an expander in a type S die set. I believe I saw in one of your articles or videos that you do use one of these now and brass necks get dings ect. Can you confirm this, and if you do, are there any modifications to the expander rod that you perform?

    • Sam
      Sam Millard
      November 27, 2019 at 04:55

      I use the expander for brass that may get fired over a concrete apron. All I do is polish the expander.

      • Tyler
        February 9, 2021 at 11:03

        For further clarification… you use the neck bushing and the expander in the same operation to smooth out the dented necks or do you perform those separately. I have a lot of .223 dented neck casings and wondering if I would be able to FL size, set neck grip, and smooth the dents in one pull.

        • Sam
          Sam Millard
          February 9, 2021 at 18:40

          Because of all the dented necks from competition shooting, I’ve switched almost 100% over to sizing with the expander in place in my bushing dies. One pull and it’s done.

          • Tyler
            February 13, 2021 at 20:49

            Alright. If you have the neck bushing inserted, but pull the case back through the expander button after it’s been neck sized, your case neck is being set by the expander button, no?

  • Jerry Nighswander
    January 12, 2020 at 19:21

    I have started using the Redding Type S dies at your suggestion. I run into a problem with Nosler brass being used for my 308 – I am using the .331 neck bushing but when In measure the neck they are being squeezed down between .3300 to .3295. I brass is very clean and I don’t know why the brass not coming out with the .331 diameter?

    • Sam
      Sam Millard
      January 13, 2020 at 13:09

      Try another bushing. Maybe it’s not marked correctly?

  • bob cox
    January 15, 2020 at 02:14

    high Sam. i’m a newbe to long range shooting. can you tell me he difference between 6.5 prc and 260 rem as far as powder burning, barrel life,etc ?

    • Sam
      Sam Millard
      January 15, 2020 at 05:17

      I would guess the PRC is like the 260 Terminator. More powder/speed than the 260 Remington, and half the barrel life.

  • Chad
    April 12, 2020 at 10:25

    Hey Sam, I’ve grown to love your YouTube channel and wanted to thank you for all of its content (although my wife thinks I’m crazy, lol) as well as your website. Do you make it a practice with new brass, just because it’s new, to run an expander mandrel through the first sizing or do you still only use the FL bump die with a bushing? Thanks again and take care!

    • Sam
      Sam Millard
      April 14, 2020 at 04:26

      It depends on neck O.D. If it’s more than .001″ under loaded diameter, I run them over a mandrel first.

  • paul Sims
    May 21, 2020 at 21:49

    Sam, Paul Sims here, been watching and reading your site for a couple of weeks and am impressed with your knowledge! I noticed Your take on the Redding dies and my question for You is; will the dies work on the Lee press (hand loader)? Thank You for answer in advance.
    Paul Sims

    • Sam
      Sam Millard
      May 22, 2020 at 04:51

      I don’t know anything about the Lee press. Redding dies use the standard 7/8-14 threads.

  • John Lucas
    June 7, 2020 at 04:58

    In response to Paul Sims question…..I have been using The breechlock classic press for many years along with Redding bushing dies. The combination makes very concentric, quality and accurate ammo.

  • Lefty Arlinghaus
    October 28, 2020 at 14:33

    Hi Sam, Thank you for the incredible content both on video and on the web site. I am standing on the abyss of reloading, and ready to take the leap. I shoot long range (out to 1K yards) with my RPR, chambered in 6.5 CM. I feel confident to do that because of your excellent work sharing experience and results. My question is when sizing the bushing for the neck tension, your info makes sense, but does it matter if I use factory ammo to measure neck O.D. before subtracting the 0.001″ width. In other words, I have good quality Berger bullets on hand that are factory produced. Will that neck OD value off that store-bought round be a suitable reference?

    • Sam
      Sam Millard
      October 31, 2020 at 03:40

      The brass thickness is the biggest variable. You should be close if using the same cases.

  • Galen Lee
    November 15, 2020 at 20:19

    In response to some other in the comments, I am having the “oversizing” issue y’all are having. My loaded round is 0.335″ so I purchased a 0.334″ and a 0.333″ bushing. My fireformed OD is 0.340″, so in theory I am only sizing down 0.006″ with a .334 bushing. However, my 0.334″ bushing sizes my cases to 0.332″ and my 0.333″ bushing sizes cases to 0.331″. Redding mentions the oversizing issue due to a large amount of sizing usually more than 0.008-0.010″ of sizing and that some use a two step method or will buy a larger bushing to compensate for this oversizing. Redding also states “Likewise, one cannot measure the neck of a “sized” piece of brass to determine a bushing’s size. Because of springback and the metallurgic properties of brass, the neck of a sized case will not reflect the exact inside diameter of the bushing that it was sized in.” So I have purchased a .335, .336, and a .337 bushing and am going to size and see what happens. I will also add that these cases have just been annealed.

  • richard
    March 6, 2022 at 07:29

    I’m very happy to find your explanations on bushings…began loading in 1960’s until early 1990’s…haven’t since then….was very confused about bushings…..until read about:

    Choose your brass, seat bullet, measure then subtract…I couldn’t get it through my head because the loaded cartridges and brass from different manufacturers might all be different….now I understand.

    Thank you.

  • Wave Runner
    March 15, 2023 at 19:52

    First question, I don’t see how the “Choose your brass, seat bullet, measure then subtract” can be accurate. If I seat the bullet, what tension am I seating it at, and how do I perform THAT seating tension? And if I’m seating a bullet at a, let’s say .001 in tension, then the bushing size would be measured diameter, NOT the diameter minus the .001 in, that tension is already part of the measured diameter.
    The other issue I found lacking in descriptions of brass preparation for us beginners, is that when preparing brass, we are actually targeting at minimum three entirely different processes. (1) reloading brand-new brass, (2) reloading fired brass from the primary rifle, and perhaps (3) reloading brass from unknown rifles for the primary rifle. Each requires a different set of measurements and steps. This fact seems to be skipped over by many authors.
    My final question is, from what I’ve read above, a mandrel sizing is often required for new brass and dented brass. So why not just use mandrel neck sizing ALL the time instead of bushings? This approach will not be dependent on brass thickness and having to use a different bushing for different brass? Thank for your otherwise excellent information and guidance.

  • D.S.W.
    January 20, 2024 at 17:52

    You neglected to include the normal .001 brass springback in your calculations. Obviously that can very predicated upon when the brass was annealed last.


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