Garand Thumb Tests .300 Blackout Loads in Ballistic Gel, Loud and Quiet

Garand Thumb is back with a follow-up on .300 Blackout lethality, this time pulling in both supersonic and subsonic loads after viewers called out the gaps in his original test. Shooting out of a 6.75 inch barrel, the length he says matches what most militaries and police agencies run, he fires a lineup of projectiles into ballistic gel and catches the impacts on a Phantom camera running around 110,000 frames per second.

Key points

• Supersonic standouts: The Sig 120 grain short-barrel monolithic copper round clocked 1,911 fps and produced what Garand Thumb calls an explosive compression in the gel with full penetration.
• FMJ surprise: The Hornady Frontier 125 grain FMJ, running 1,877 fps, showed more yaw and drawing effect in gel than the Sig 125 grain OTM, which he says he did not expect from a basic FMJ.
• Subsonic physics: He explains subsonic rounds lack the velocity for easy fragmentation or tumbling, so performance leans heavily on how the projectile itself is engineered.
• Sig ME subsonic: The 194 grain Lehigh-made Sig ME load chronographed at 867 fps and petaled open dramatically in gel, which Garand Thumb says explains why it is popular with certain units.
• Caliber context: He notes .300 Blackout's roughly .30 caliber bullets have less surface area than a 9mm, .40 or .45, so they are asking more of the projectile design to get similar expansion.

Quick take

This is a straightforward, hardware-heavy look at how different .300 Blackout loads actually behave on impact, both loud and quiet, with real velocity numbers and slow-motion gel footage instead of just opinions. Worth watching if you run a Blackout gun and want to see which projectiles earned their reputation.

Watch the full video: Garand Thumb