Making 300 Win Mag 'Hollywood' Quiet

Published on April 5, 2025
Duration: 10:02

This video details an experiment to achieve subsonic velocities with 300 Winchester Magnum ammunition using Hodgdon Trail Boss powder and 208-grain bullets. The instructor tests various reduced charge weights, documenting chronograph readings and impact shifts. While subsonic velocities were not achieved, the experiment highlights the challenges of loading large-case magnum cartridges for suppressed use and identifies a promising reduced-recoil load capable of stacking groups.

Quick Summary

Loading subsonic 300 Winchester Magnum ammunition is challenging due to the cartridge's large case capacity. An experiment using 208-grain bullets and Hodgdon Trail Boss powder, with charges ranging from 18 to 20 grains, did not achieve subsonic velocities (below ~1125 ft/s), with readings consistently above 1300 ft/s.

Chapters

  1. 00:00Intro: Subsonic 308 vs 300 Win Mag Goal
  2. 01:06Supersonic vs. Subsonic Explained
  3. 01:54Testing Full Power 178gr Hornady Match Ammo
  4. 02:50Full Power Velocity Readings
  5. 03:19Impact Analysis of Full Power Ammo
  6. 03:47Preparing for Subsonic 300 Win Mag Test
  7. 04:18Reloading Subsonic Loads: 20gr Trail Boss
  8. 04:59Velocity Test: 20gr Trail Boss (Supersonic)
  9. 05:35Reloading Subsonic Loads: 18gr Trail Boss
  10. 05:56Velocity Test: 18gr Trail Boss (Supersonic)
  11. 06:13Impact Analysis of Reduced Loads
  12. 06:51Shooting Steel with 19gr Trail Boss Load
  13. 07:48Steel Target Ringing: 19gr Trail Boss at 100 Yards
  14. 08:06Conclusion: Subsonic 300 Win Mag Challenges
  15. 08:43Key Takeaway: Reduced Recoil & Accuracy
  16. 09:15Support the Channel: TA Targets

Frequently Asked Questions

What is the primary goal of making 300 Win Mag ammunition subsonic?

The main objective is to eliminate the sonic crack produced by a bullet traveling faster than the speed of sound. This is particularly beneficial when using a suppressor, as it significantly reduces the overall noise signature of the firearm.

What components were used in the attempt to create subsonic 300 Win Mag loads?

The experiment involved a Bergara B14 HMR Wilderness rifle, 208-grain bullets, and Hodgdon Trail Boss powder. Various charge weights were tested, starting with 20 grains and decreasing to 18 and 19 grains.

Were subsonic velocities achieved with the tested 300 Win Mag loads?

No, subsonic velocities were not achieved. The tested loads, even with reduced charges of Trail Boss powder and 208-grain bullets, consistently registered velocities between 1330 and 1449 ft/s, which are still supersonic.

What are the challenges in loading subsonic 300 Win Mag ammunition?

The significant case capacity of the 300 Win Mag makes it difficult to achieve subsonic velocities with standard bullet weights. It requires very low powder charges, which can lead to inconsistent ignition or even squib loads if not carefully managed.

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