July 1st, 2021

Tips for Using Lee Collet Dies for Neck-Sizing Brass

LEE Precision Collet Die

Editor’s NOTE: We generally recommend full-length sizing your cases. But there may be some situations where you may want to body-size your brass in one operation, and then neck-size the case as a final operation for reduced run-out. Or, perhaps you have a non-bushing FL sizing die and you want to modify the neck sizing. This article explains how to use a Lee Collet Die to size case-necks.

For those who prefer to neck-size their brass (rather than full-length-size), the LEE Collet Die is a popular, inexpensive option. It works by having collet tangs or “fingers” press the neck against a central mandrel. A collet squeezes the case neck against a precision mandrel for a perfect fit with minimum run-out. The benefit is that you get a very straight neck, which is sized consistently from top to bottom. Canadian shooter Jerry Teo explains: “LEE Collet Dies produce sized cases with very low runout (measured runout is under .001″ using a Sinclair concentricity gauge). You also don’t get the build-up of brass at the base of the neck, as can happen with bushing neck dies. The neck-shoulder junction stays nice and crisp.”

Here’s a good video that explains how to use a Lee Collet Die to Neck-Size .243 Win brass:

UPDATE to LEE Collet Dies — Neck Protrusion Change
The Lee Precision website notes a small design change: “If you’re a long-time user of Lee Collet Neck Sizing Die you may notice we have modified the Collet so a small portion of the neck protrudes through the end of the Collet-sizing portion. This often-requested modification was implemented in 2019. This change allows the portion of the neck that protrudes above the Collet to remain in its fire-formed condition. This provides a natural flare to the case neck allowing easy and concentric seating of bullets. This is especially important when seating cast bullets or low-drag coated bullets.”

LEE Precision Collet DieTIP ONE — Adjusting Tension
LEE Collet dies don’t have a specific mechanical adjustment for neck tension. But you CAN easily modify the die to provide more or less tension. If you want to adjust the neck tension using a Lee Collet die, you can simply chuck the mandrel in a drill and reduce the diameter with some sand-paper (to increase neck tension) or you can order a mandrel the next caliber larger and turn it to whatever diameter you want (the larger the mandrel diameter, the less the neck tension). You can also order custom mandrels from Lee sized to any diameter you want.

Regarding neck tension, Boyd Allen makes an important point: “The only way to properly get more neck tension with collet dies is to either reduce the diameter of the mandrel, or order a smaller-diameter mandrel from Lee. I remind folks that adjusting the die position to have more toggle at the top of the ram stroke (not the factory recommended method), or leaning on the press handle with more force than recommended will NOT increase neck tension.”

No Custom Lee Collet Dies For Now
In years past, Lee also offered Custom Collet Dies, made from two fired cases. Hopefully these will be available in the future. However, earlier this year, Lee announced it had suspended sale of most custom dies including Collet Dies: “March 17, 2021: Due to unprecedented order volume, we have suspended custom services for Collet Necksizing Dies, Full-Length Sizing Die Sets, Quick Trim Dies, Case Length Gauges, Factory Crimp Dies, and Bullet Molds until we are able to meet the required volume of our standard products.”

TIP TWO — Polish and Tune for Easy Case Removal
Some users have complained that their Collet Dies grab the case-neck too firmly, making the case hard to remove. There are solutions to this problem. First inspect the collet fingers and smooth the inner surface up a bit with polishing compound or an extra-fine sanding pad. Second, you can open up the fingers a little bit. LEE recommends that if your Collet Die is sticking, take a steel punch and tap the fingers apart a little bit so that the natural “unloaded” position is wider. Lastly, you should lightly lubricate the outside of the collet fingers (see arrows) before you re-assemble the die. This will ensure they slide smoothly. Also, to prevent the collet fingers from closing too tight, never load up the die with your press without putting a case in place first. Without a case neck between the collet fingers and the mandrel, the collet can clamp itself too tight as you raise the ram.

TIP THREE — Always Have a Case Inside When Operating Collet Die
Our friend Boyd Allen tells us that you need to follow directions and NEVER operate the die without a case inside. Boyd explains: “This is because doing so will spring the quadrents of the collet inward so that they interfere with the insertion of a case, and the user will have to figure out how to undo the damage if the die is to operate properly. This advice would not be needed if everyone read the instructions before using the die…. but many times, they don’t. Another thing that I tell new users is to take the die apart so that they will have a better chance of understanding how it works.”

TIP FOUR — Size Twice and Spin Your Case 1/8th Turn
After reaching fully “down” on your press handle, withdraw the case about an inch and manually rotate it about 1/8th (NOT 1/4 or 1/2) turn while still in the shell-holder, then size again. This will place the die’s collet petals on the four “high spots” of the case neck and will result in a rounder, more evenly-sized neck with slightly more bullet tension. This takes only about one second more per case and is well worth the slight extra effort. (We thank reader Stonecreek for this smart tip).

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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

Article Find by EdLongrange. We welcome reader submissions
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