January 16th, 2020

SIZING DIES: Full-Length Dies, Neck-Sizing Dies, Small Base Dies

Sizing dies brass sinclair redding full length neck neck-sizing small base

This article is part of Sinclair Int’l Step-By-Step Reloading Series. Most of the products mentioned in this article are sold through Brownells.com.

by Roy Hill, Brownells/Sinclair Copywriter
Making your own precision handloads is a meticulous journey with many steps, many important matters to consider, and many sets of measurements to calculate. For those who pursue the perfect group, the highest score, the really long accurate shot, the rewards more than outweigh the effort. Choosing the right cases, deburring the flash holes, making the primer pockets uniform, trimming the cases, and lubricating them are all familiar – and critical – steps along the journey. And now that your brass preparation is complete, you are at last ready to start running the cases through your press and fill them with primers, powder, and bullets. The very first die the brass encounters is the sizing die. You insert the case, work the press’s lever to return the case to its correct pre-fired dimensions – and the journey continues.

Sinclair International Int'l fL full-length sizing die bump die shoulder bump gauge

There are three types of sizing dies to think about: neck, full-length, and small base. All three have specific benefits and potential drawbacks, and you should choose the type of die you use by thinking very carefully about what kind of shooting you plan to do with your handloads. No matter which type you select, most sizing dies will also punch out the old spent primer with some sort of decapper assembly that uses a hardened steel rod. Many types of sizing dies use an expander ball inside the die to make sure the neck of the case will accommodate a bullet after being sized. With some size dies, the expanders are easily removable and interchangeable, letting you get exactly the neck tension you want. If you are reloading for pistol cartridges, carbide sizing dies allow you to quickly resize without applying any lube to the case. But rifle cases always need lube.

Neck-Sizing Dies
Sinclair International Int'l fL full-length neck size neck-sizing die bump die shoulder bump gaugeNeck-sizing dies resize only the neck of the case. The benefit of sizing only the neck is that the brass is “worked” very little, letting you reuse the same cases many times over. Also, cases that have already been fired in your rifle are perfectly fireformed to fit that rifle’s chamber, which can help accuracy. However, neck-sized cases will fit only the specific rifle they were originally fired in, and may still require a little extra force to chamber or extract.

Sinclair recommends that neck-sized-only cartridges should not be used any in other rifle besides the one they were originally fired from [unless they are also FL-sized], or in any action other than a bolt-action. Neck-sized-only rounds are great for the target range or the benchrest but should not be used in critical situations like military or police operations, or hunting. And if you fire them enough times, neck-sized cases will still need to be full-length sized periodically for you to keep using them.

Full-Length Sizing Dies
Full-length sizing dies do exactly what their name says: resize the full length of the case, not just the neck. Full-length sizing helps create handloads that will function in any rifle, not just the one from which the cases were originally fired. The potential downside of full-length sizing is that it may shorten case life because it works the brass more than neck sizing. But it’s possible to “tune” today’s full-length sizing dies so they barely work the brass at all, as this article by Sinclair Reloading Tech Ron Dague shows.

Illustration Shows How a Full-Length Sizing Die Works
Sinclair International Int'l fL full-length sizing die bump die shoulder bump gauge

Another way to reap the benefits of full-length sizing is to use Redding’s full-length bushing dies, which size the full length of the case but use a system of interchangeable bushings that enable you give the case neck the bare minimum of resizing needed. To see how finely adjustable bushing dies are, and how they resize the case while fully supported, CLICK HERE for Video. The neck bushing helps you precisely control the neck tension to help increase the consistency and accuracy of your handloads.

Redding Custom full length dies

Small Base Dies
A Small Base Die is just another type of full-length sizing die, but one that is typically used when reloading for semi-automatic rifles, like the AR-15, M14, or AR-style .308 rifles. (It may also work well for bolt guns that need extra sizing on the lower section of the case.) A small base die works exactly like a full-length sizing die, only it compresses the brass just a bit more, usually about .001″ more, and may even push the case shoulder back just a hair. Small base dies give that extra bit of compression to the brass to help make sure the case will properly extract from a semi-automatic firearm. The upside is that you get precision handloads that should work flawlessly in your semi-automatic. The downside is case life is really shortened, especially compared to brass used only in one bolt-action rifle, because the brass is worked more.

Shoulder Bump Gauges
A handy tool for setting up your full-length sizing dies as close as possible to your rifle’s chamber is the Sinclair bump gauge. The bump gauge lets you resize the case as little as possible, to extend case life and help your handloads fit your rifle almost like a neck-sized only die. You use deprimed cases fired in your rifle and bump gauge inserts to help you set up the die so it resizes the case only about .001″ to .004″, depending on what type of rifle you’re shooting.

Video shows how to use a shoulder bump gauge to set up your full-length dies

Sinclair International Int'l sizing die bump die shoulder bump gauge

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August 23rd, 2019

Choosing the Best Neck Bushing Size — Tips from John Whidden

John Whidden Dies Neck Bushing diameter reloading

Whidden Gunworks makes great sizing and seating dies. The Whidden full-length sizing die with neck bushing is very popular because it allows you to “tune” the neck tension by using different bushings, with larger or smaller inside diameters. In this video, John Whidden explains how to choose a the right bushing size for use with your neck-sizing and full-length sizing bushing dies.

For most applications, John suggest starting with the caliper-measured outside diameter of a loaded cartridge (with your choice of bullet), and then SUBTRACT about three thousandths. For example, if your loaded round mics at .333, then you would want to start with a 0.330 neck bushing. John notes, however, that you may want to experiment with bushings, going down a thousandth and up a thousandth. With thin In addition, as your brass ages and the necks harden, you may want to change your bushing size.

John Whidden Dies Neck Bushing diameter reloadingQuick Tip: Try Flipping Your Bushings
You may also want to experiment with “flipping” your neck bushings to alternate the side that first contacts the neck of the case. (One side of the bushing is usually marked with the size, while the other side is unmarked.) So try “number side up” as well as “number side down”.

Some folks believe that one side of the bushing may allow a smoother entry, and that this can enhance concentricity. Other people think they can get very slightly more or less neck tension depending on how the bushing is oriented. This is a subtle effect, but it costs nothing to experiment.

If one bushing orientation proves better you can mark the “up” side with nail polish so that you can always orient the bushing optimally. NOTE: We have confirmed that some bushings are actually made with a slight taper. In addition, bushings may get distorted slightly when the brand name and size is stamped. Therefore there IS a reason to try both orientations.

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August 16th, 2019

RCBS Offers New MatchMaster Sizing and Seating Dies

rcbs reloading matchmaster loading die seating die micrometer bushing neck sizing die full-length

RCBS has introduced a new series of MatchMaster Competition Dies. These are available in Full-Length Sizing, Neck Sizing, and Seating configurations. These new MatchMaster dies are notable for four features:

1. The Competition Seating Die has a “view-port” for the bullet.
2. The Competition Seating Die features a free-floating, self-centering bullet-seating stem.
3. Expanders are titanium-nitride coated for reduced friction. Both the Neck-Sizing and FL-Sizing dies come with TiN expanders for smoother case extraction and reduced brass build-up on the expander.
4. RCBS is offering its own precision-machined Neck Bushings.

No More Mashed Fingers When Seating Bullets
RCBS notes: “Reloaders will love that they can end smashed fingers and misaligned bullets with the specially-designed bullet window [on the Seating Die]. And users can fine-tune any load … with the micrometer-adjustable, free-floating, self-centering bullet seating stem.”

RCBS Product Manager Will Hemeyer explained that the new Competition Seater is a game-changer. “What sets the MatchMaster Seating Die apart from the competition is a bullet-seating window with bullet-retaining system. Simply place the bullet in the window and raise the case into the die to seat the bullet. Couple this with a micrometer-adjustable, free-floating, self-centering bullet-seating stem and the MatchMaster Seating Die is easily the most accurate bullet seating die on the market.”

Gavin Gear of UltimateReloader.com has tested the new RCBS MatchMaster Dies in 6mm Creedmoor. He was very impressed with the new Competition Seater and he liked the TiN-coated expanders on the sizing dies. Watch Gavin’s video:

rcbs reloading matchmaster loading die seating die micrometer bushing neck sizing die full-length

Why Use Expander with Bushing Dies?
Some viewers of Gavin’s video asked if an expander is superfluous when using neck-bushing dies. The answer is “it depends”. The bushings reduce neck diameter from the OUTSIDE. The expander should make the INSIDE of the neck perfectly round. Some hand-loaders prefer to take the necks down a couple thousandths below final loading diameter, then finish the job with an expander. That ensures the INSIDE of the case neck is perfectly concentric. This can be particularly useful for brass that has somewhat inconsistent neck-wall thickness. Bottom line, you can run these dies without expanders if you want, but that option is available. The expander is also removable so the assembly can be used for de-capping only.

MactchMaster Neck-Sizing Only Die
The MatchMaster Neck Sizing Die Set also uses RCBS neck bushings to control neck tension while not changing the body dimensions of fired cases. Frankly we strongly recommend that you full-length size your rifle rounds, but we acknowledge that some hand-loaders prefer to neck size for some applications. The MatchMaster Neck Sizing Dies do include a titanium-nitride coated expander, just like the FL-sizing MatchMaster dies.

To learn more about the new MatchMaster Competition Dies, visit www.RCBS.com.

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April 18th, 2019

Smart Reloading: How to Set Optimal Case Neck Tension

USAMU handloading Neck Bushing Die tension springback interchangeable bushings

Each Wednesday, the U.S. Army Marksmanship Unit (USAMU) publishes a reloading “how-to” article on the USAMU Facebook page. A while back, the USAMU’s reloading gurus addressed a question frequently asked by handloaders: “How much neck tension is optimal, and how should I select a neck bushing size?” The USAMU offers a straight-forward answer, suggesting that hand-loaders start with a neck bushing that sizes the neck so that it is .003″ less than the loaded outside diameter with bullet in place. From there, you can experiment with more or less tension, but this is a good starting point for many popular cartridge types.

USAMU Reloading

Determining Optimal Case-Neck Tension

This week, we examine determining the correct case neck tension for optimum accuracy. Our method is simple, but relies on the use of case sizing dies which accept interchangeable neck diameter bushings graduated in 0.001″ increments. (Those readers using fixed-diameter dies with expander balls aren’t forgotten, however. Methods of tailoring these dies for proper neck tension will be found below.)

In our experience across many calibers, sizing case necks 0.003″ under the loaded-case neck diameter usually yields excellent accuracy. In other words, the sized case neck expands 0.003″ when the bullet is seated.

USAMU handloading Neck Bushing Die tension springback interchangeable bushings

USAMU handloading Neck Bushing Die tension springback interchangeable bushingsBushing Choice for Optimal Sizing
Over the years, we have periodically experimented with increasing neck tension to possibly improve accuracy. In testing with machine rests at 300/600 yards, accuracy often deteriorated as neck tension increased; thus, 0.003″ expansion (from sized neck to loaded neck) is where we usually start.

Using the .260 Remington as an example, our loaded cartridge case necks measure 0.292”. Simply subtract 0.003” from that, and use a bushing that sizes necks to 0.289” (after springback). There are exceptions — sometimes, brass may be a bit soft or hard. Some case necks might need, say, 0.001” more tension, but in general, this works well.

This .003″ standard of neck tension works very well for single-loaded, long range cartridges. Depending on your caliber and firearm, it MAY also work very well for magazine-fed cartridges. If this neck tension proves inadequate for your purpose, one can increase neck tension as needed while monitoring for possible accuracy changes.

Special Considerations for Coated Bullets: If you are using moly-coated bullets, this significantly reduces the “grip” of the case neck on the bullet, and you can expect to have to tighten your case necks accordingly — particularly for magazine-fed ammunition. In any event, we do not crimp rifle cartridges, and advise against it for accuracy handloads.

Tips for Using Expander Balls
Many savvy handloaders avoid the use of expander balls in high-accuracy reloading, if possible. These can stretch cases and/or disturb the concentricity of the case neck vs. case body. If using a die with an expander ball, tapering both ends of the ball and polishing it to a mirror finish can significantly reduce these effects. (Special carbide expander ball/decapping stem sets are available for this as well.)

The typical dies used with expander balls are intended to take any cases the user may find, and size them down well below the ideal “spec” to ensure any cases will give good neck tension. The necks are then expanded up to provide heavy to medium neck tension as the expander ball exits the neck. The brass is over-worked, leading to premature work-hardening, and seated-bullet concentricity may suffer. However, the cartridges produced are perfectly adequate for most handloaders. Those who seek finest accuracy generally prefer not to over-work their brass if possible.

Another Option — Custom-Honed FL Dies
There are companies which offer to convert one’s standard dies to accept neck bushings, and that gives excellent flexibility. Another, more “old-school” approach, is to have the neck of one’s FL die honed out to the desired diameter for sizing, based on one’s case neck thickness. The expander ball may then be reduced until it barely touches the case necks after sizing, or it may be eliminated entirely. However, once performed, this modification is permanent and leaves fewer options than the bushing route, if one later changes case neck thickness.

Those shooters who turn their case necks for optimum neck wall thickness uniformity, or for a tight-neck chamber, will want to take the reduced neck wall thickness into consideration. For example, when setting up a 7mm match rifle to use a standard hunting die without an expander ball, the slightly thinner necks resulted in a perfect 0.003″ reduction in the fired-neck diameter. The result was a low-cost die that fit with custom precision and yielded excellent, match accuracy!

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