.357 Magnum - My first test loads for the GP100

Published on January 15, 2017
Duration: 32:48

This video details the process of reloading .357 Magnum ammunition for the first time, using 158-grain Hornady XTP bullets and Winchester 296 powder. The instructor demonstrates case preparation, powder charging, bullet seating, and crimping, while also providing initial range testing with velocity and group data. The content is presented from the perspective of a reloader new to this specific caliber, offering a learning process for viewers.

Quick Summary

Reloading .357 Magnum involves careful preparation of Starline brass, using Winchester 296 powder and 158-grain Hornady XTP bullets. Specific die adjustments are crucial: 2 3/4 turns off for the sizing die and 4 3/4 turns for the seating die, aiming for an overall length of 1.590 inches. Tested loads of 13.5 grains yielded around 1,731 ft/s, while 15.0 grains averaged 1,161 ft/s.

Chapters

  1. 00:01Introduction to .357 Magnum Reloading
  2. 00:49Focus on .357 Magnum Loads
  3. 01:09Bullet Selection: 158gr Hornady XTP
  4. 02:05Powder Selection: Winchester 296
  5. 02:16Primer Selection: WSPM
  6. 02:34Load Data from Hornady Manual
  7. 02:38Brass Preparation: Starline .357 Magnum
  8. 03:31Charge Weights: 13.5gr and 15.0gr
  9. 04:29Overall Length Target: 1.590"
  10. 04:36Sizing Die Setup for .357 Magnum
  11. 06:54Priming Cases
  12. 07:08Powder Charging with W296
  13. 08:11Bullet Seating Die Setup
  14. 09:06Crimp Die Setup
  15. 10:13Adjusting Seating Depth
  16. 12:51Applying Factory Crimp
  17. 13:37Chamber Check
  18. 14:17First Successful .357 Magnums Loaded
  19. 15:15Loading Complete & Review
  20. 16:02Range Day: Chronograph Setup
  21. 16:35First Shot: 13.5gr Load Test
  22. 17:17Velocity Data: 13.5gr Load
  23. 17:59Accuracy Check: 13.5gr Load
  24. 18:22More 13.5gr Shots
  25. 19:59Velocity Data Analysis: 13.5gr Load
  26. 20:24Transition to 15.0gr Load
  27. 20:34First Shot: 15.0gr Load Test
  28. 20:54Velocity Data: 15.0gr Load
  29. 21:10Shooting 15.0gr Load Cylinder
  30. 21:47Brass Extraction & Analysis: 15.0gr Load
  31. 21:59Velocity Data Analysis: 15.0gr Load
  32. 22:21Switching to Steel Targets
  33. 22:47Shooting Steel with 13.5gr Loads
  34. 26:21Shooting Steel with 15.0gr Loads
  35. 31:38Bench Talk: Reloading Recap
  36. 31:49Accuracy & Sight Adjustment
  37. 32:23Firearm Functionality & Ammo Performance
  38. 32:33Conclusion: Successful First Reload

Frequently Asked Questions

What are the recommended load data ranges for 158-grain Hornady XTP bullets with Winchester 296 powder in .357 Magnum?

According to the Hornady manual, the starting charge for 158-grain XTP bullets with Winchester 296 powder in .357 Magnum is 12.4 grains, and the maximum charge is 16.0 grains. The video tests 13.5 grains and 15.0 grains.

What is the correct overall cartridge length for .357 Magnum reloads using 158-grain bullets?

The target overall cartridge length specified in the video for .357 Magnum reloads with 158-grain bullets is 1.590 inches. The reloader achieved lengths around 1.583 to 1.587 inches, which was deemed acceptable.

How should the sizing and seating dies be adjusted for reloading .357 Magnum?

For .357 Magnum, the sizing die is adjusted 2 3/4 turns off the shell holder for proper flaring. The bullet seating die is set 4 3/4 turns off the shell holder to achieve the target overall cartridge length.

What were the observed velocities for the tested .357 Magnum loads?

The 13.5-grain load of Winchester 296 with a 158gr XTP averaged 1,731 ft/s. The 15.0-grain load averaged 1,161 ft/s, with a minimum of 1,087 ft/s and a maximum of 1,203 ft/s.

Related News

All News →

More Training & Techniques Videos You Might Like

More from Johnny's Reloading Bench

View all →