300 Win Mag - Getting started with reloading

Published on December 28, 2018
Duration: 102:45

Instruction from a firearms enthusiast and reloader on preparing and sizing 300 Winchester Magnum brass. The video details the challenges of reloading for this caliber, including the long throat of the Thompson Center Compass rifle and the importance of proper neck tension and shoulder bumping. It covers selecting collets, setting up sizing dies, using specialized tools for case maintenance, and determining optimal seating depths for accuracy.

Quick Summary

Reloading 300 Winchester Magnum requires careful brass preparation, including proper sizing to bump the shoulder 2-3 thousandths and achieving adequate neck tension (2-3 thousandths). Due to long rifle throats, seating bullets longer than SAAMI max is often necessary to reduce jump to the lands and improve accuracy.

Frequently Asked Questions

What is the recommended method for setting up a full-length sizing die for 300 Winchester Magnum?

For 300 Win Mag, set up the full-length sizing die to bump the shoulder back 2-3 thousandths of an inch from the fired dimension. This ensures proper chambering without overworking the brass. Measure fired cases and adjust the die until the resized case headspace is slightly less than the fired dimension.

How do you achieve proper neck tension when reloading 300 Winchester Magnum?

Achieving proper neck tension involves selecting the correct collet size for your sizing die based on measured neck wall thickness. Aim for 2-3 thousandths of neck tension. Insufficient tension can lead to bullet pull, while excessive tension can increase pressure and make seating difficult.

Why is it important to measure the jump to the lands for 300 Winchester Magnum reloads?

The 300 Win Mag, particularly in rifles like the Thompson Center Compass, often has a long throat. Measuring the jump to the lands and seating bullets longer than SAAMI maximum allows for reduced jump, which can significantly improve accuracy by engaging the rifling sooner.

What are the key brass preparation steps for 300 Winchester Magnum reloading?

Key steps include inspecting and sizing brass, trimming to length (e.g., 2.620 inches), deburring case mouths and flash holes, and ensuring proper neck tension. Specialized dies may be needed to manage case growth above the belt.

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