Rim vs Rimless

Published on November 26, 2025
Duration: 2:59

This video from C&Rsenal, presented by a knowledgeable instructor, delves into the fundamental differences between rimmed and rimless cartridges. It explains the historical advantages of rimmed cases, such as safety in tubular magazines and easier extraction, while detailing why rimless designs became dominant with the advent of autoloading firearms due to improved feeding reliability and capacity. The expert analysis highlights key mechanical and safety considerations for firearm design.

Quick Summary

Rimmed cartridges historically offered safety benefits like acting as a gas check if a case splits and simplifying headspace in bolt-action rifles. They are also easier to extract and safer in tubular magazines. However, rimless cartridges became the standard for autoloading firearms due to their superior feeding reliability and higher capacity potential in vertical magazines, avoiding issues like 'rim lock'.

Chapters

  1. 00:00Introduction: Rimmed vs. Rimless Cartridges
  2. 00:27Historical Advantages of Rimmed Cartridges
  3. 01:23Safety in Tubular Magazines (Rimmed)
  4. 01:44Extraction Benefits of Rimmed Cases
  5. 02:05The Shift to Rimless for Automation

Frequently Asked Questions

What are the main advantages of rimmed cartridges?

Rimmed cartridges historically offered safety benefits like acting as a gas check if a case splits. They also simplify headspace in bolt-action rifles and are easier to extract due to the rim providing a clear ledge for the extractor, especially useful in revolvers.

Why did rimless cartridges become the standard?

Rimless cartridges became dominant with the rise of autoloading firearms. Their design prevents 'rim lock' in vertical magazines, allowing for more reliable feeding and higher ammunition capacity compared to rimmed cartridges in these systems.

How do rimmed cartridges improve safety in tubular magazines?

In tubular magazines, the rim of a rimmed cartridge causes the rounds to stack at an angle. This prevents the bullet tip of one cartridge from resting directly on the primer of the next, significantly reducing the risk of accidental discharge under recoil.

What is 'rim lock' and why is it relevant to cartridge design?

'Rim lock' occurs when the rims of rimmed cartridges snag on each other in a magazine, preventing proper feeding. This issue is avoided with rimless cartridges, making them essential for the reliable function of modern autoloading firearms with vertical magazines.

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