Gordon's Reloading Tool (GRT) Basics Part 9: Seating Depth Misdirection (GRT White Lies?)

GRT Basics Part 9: Seating Depth Misdirection (GRT White Lies?) GRT says seating your bullet deeper will spike chamber pressure. I loaded real rounds, shot real groups, and the results say otherwise. Here's what's actually happening — and why GRT gets this wrong. Gear used in this test: Savage 10FP - 308 Winchester Hornady 150gr SST bullets Vihtavuori N140 powder Federal 210 LR primers Lee 308 Seating Stem w/ Micro Adjuster: https://amzn.to/4uPOitr Lee 308 Collet Neck Die Only: https://amzn.to/43xSQcB MagnetoSpeed Chronograph: https://amzn.to/4vOqfvQ Athlon Rangecraft Doppler Chronograph: https://amzn.to/4ee3OZz Caldwell The Rock Front Shooting Rest: https://amzn.to/4avVnI3 Lyman 50th Edition Reloading Manual (SAAMI pressure data referenced in this video): https://amzn.to/4v7hsF2 Forster Reloading Myths That Are Hurting Your Accuracy:    • Reloading Myths That Are Hurting Your Accu...   Hornady Podcast Episode 162:    • Ep. 162 - Uncomfortable & (Maybe) Mind-Alt...   ⏰Timecodes⏰ 00:00 Under Pressure? Seating Depth vs Chamber Pressure Explained 00:08 GRT Seating Depth Problems and Pressure Prediction Errors 00:45 Does Seating a Bullet Deeper Increase Pressure? 01:24 SAAMI Pressure Limits for 308 Winchester 02:18 How the Seating Depth Pressure Test Was Built 03:18 Why GRT Shows Pressure Spikes With Shorter COAL 04:06 Seating Depth Test Spreadsheet and Load Data Setup 05:55 Why GRT Pressure Predictions Can Be Misleading 06:05 Bullet Seating Depth Test Rounds and Compression Effects 07:24 GRT Predicted Velocity vs Seating Depth Changes 08:04 Chronograph Testing With MagnetoSpeed and Athlon Rangecraft 09:30 Actual Velocity Results From Different Seating Depths 10:53 Real Pressure Results vs GRT Predictions 11:35 Seating Deeper Reduced Velocity? Test Results Explained 12:39 Extreme Spread Changes Across Seating Depths 13:45 Peterson Brass Interview and Precursor Flow Theory 14:22 Hornady Podcast Discussion on Gas Flow Around Bullets 15:19 Internal Ballistics Explained With Simple Animation 16:50 Why GRT Assumes the Bullet Is Near the Lands 17:36 What Happens Before the Bullet Hits the Rifling 18:16 Gas Leakage, Bullet Jump, and Pressure Behavior 19:19 Why Reloaders Start Near the Lands 19:56 Effective Case Volume and GRT Calculations Explained 21:06 Does Longer COAL Increase Pressure and Velocity? 21:40 GRT Bullet Jump Feature Warning Explained 22:24 Best Way to Tune Seating Depth in GRT 23:12 Real-World Seating Depth Testing Advice 23:46 Final Thoughts on Seating Depth and Pressure GRT Download: https://grtools.de/doku.php?id=grtool... GRT Discord Group:   / discord   GRT YouTube:    / gordonsreloading   ***************** 3D Print: https://www.printables.com/@DIY_Dewey ***************** Other great content:    / littlecrowgunworks      / reloadingweatherby      / longrangelab      / thecarcarenut   Intro Song: Queen & David Bowie - Under Pressure This description contains affiliate links. I may earn a small commission at no cost to you. #reloading #handloading #GRT