November 12th, 2016

How to Set Up Full-Length Sizing Dies and Control Shoulder Bump

Sinclair International FL full length sizing die

Sinclair International has a helpful, three-part video series on Full-Length Sizing. The full-length sizing die performs multiple important functions: it resizes the case body, resizes the neck, and adjusts the headspace relative to the chamber (it can also eject the spent primer if that was not done previously).

While neck-sizing-only can work with moderate loads (for a couple firings), after repeated firings the case can stretch, becoming too tight to chamber easily. If you shoot cases with high-pressure, near-max loads, you will probably benefit from full-length sizing your cases each reloading cycle. When full-length sizing, you will want to move the shoulder back (i.e. “bump” the shoulder) to provide proper clearance in the chamber. A case that has grown too much will exhibit stiff bolt lift after firing and be hard to chamber if it is not FL-sized during the reloading process.

Sinclair recommends bumping cases .001-.002″ (one to two thousandths) for cases used in bolt-action target-shooting rifles, or .003-.005″ (three to five thousandths) for hunting rifles or semi-auto rifles. To move the shoulder back you screw the FL-sizing die downwards in the press once you’ve determined “just touching” on the shoulder. You don’t have to screw the die down very far! With a normal 14-pitch die, 1/8th turn (45° rotation) yields approximately 0.009″ of downward movement. So it doesn’t take much to add a few thousandths of bump.

Case Sizing Part One — Why We Full-Length Resize

Case Sizing Part Two — How to Set Up Your Sizing Die

Case Sizing Part Three — How to Use a Bump Gauge

NOTE: These FLASH videos may not display on some mobile devices.

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May 5th, 2015

Intro to Full-Length Dies, Neck-Sizing Dies, and Small Base Dies

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

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

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