December 5th, 2018

DIE BASICS: 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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October 2nd, 2018

Bump Control: Precision Shims for Full-Length Sizing Dies

Sinclair Die Shims

When your cases become hard to extract, or you feel a stiff bolt lift when removing a cartridge, it’s probably time to full-length size your cases, and “bump” the shoulder back. With a hunting load, shoulder bumping may only be required every 4-5 loading cycles. Short-range benchrest shooters, running higher pressures, typically full-length size every load cycle, bumping the shoulder .001-.002″. High Power shooters with gas guns generally full-length size every time, and may need to bump the shoulders .003″ or more to ensure reliable feeding and extraction.

Use Shims for Precise Control of Shoulder Bump
Some shooters like to set the “default” position for their full-length die to have an “ample” .003″ or .004″ shoulder bump. When they need less bump, a simple way to reduce the amount of shoulder movement is to use precision shims in .001″ (one-thousandth) increments.

Here are reports from Forum members who use the shims:

“Great product. I have my die lock ring(s) adjusted for the shortest headspace length on my multiple chambers 6BRs and 6PPCs. When needing a longer headspace, I just refer to my notes and add the appropriate shim under the lock ring. Keep it simple.” — F.D. Shuster

Mats Johansson writes: “I’ve been using [shims] since Skip Otto (of BR fame) came out with them. I set up my dies with the .006″ shim, giving me the option of bumping the shoulder a bit more when the brass gets old and hardens while still having room to adjust up for zero headspace, should I have missed the original setup by a thou or two. Hunting rounds can easily be bumped an extra .002-.003″ for positive, no-crush feeding. Being a safety-oriented cheapskate, I couldn’t live without them — they let me reload my cases a gazillion times without dangerous web-stretching. Shims are a must-have, as simple as that.” — Mats Johansson

Sinclair Die ShimsSinclair Int’l offers a seven-piece set of Sizing Die Shims that let you adjust the height of your die (and thereby the amount of bump and sizing) in precise .001″ increments. Sinclair explains: “Some handloaders will set their die up to achieve maximum sizing and then progressively use Sinclair Die Shims between the lock ring and the press head to move the die away from the shellholder. Doing this allows you to leave the lock ring in the same position. These shims are usually available in increments of .001″ and work very well.”

Seven Shims from .003″ to .010″
Sinclair’s Die Shim Kit (item 22400) includes seven shims in thicknesses of .003, .004, .005, .006, .007, .008, and .010. For ease of use, shim thickness is indicated by the number of notches cut in the outer edge of each shim. Even without looking you can “count” the notches by feel. Normally priced at $11.99, this shim kit is on sale now for $10.99.

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