MythBusters · Video summary

The Mythbusters Cannon Test That Accidentally Made The News | MythBusters

The MythBusters investigate a 15th-century myth about stone cannonballs. They test whether stone cannonballs could inflict similar damage to cast iron ones and shatter on impact, preventing reuse by the enemy.

MythBusters · August 27, 2026 · 23-min episode · 5-min read

The Mythbusters Cannon Test That Accidentally Made The News | MythBusters

Key takeaways

⚠️A cannonball misfire during the episode's filming resulted in a cannonball accidentally going through someone's house, leading to an immediate halt of the experiment and a comprehensive safety review.00:05
💡The myth of stone cannonballs emerged from the strategic dilemma of 15th-century cannoneers who wanted to avoid giving valuable cast iron projectiles to the enemy.00:43
💨The true battle speed of a steel cannonball from an antique Civil War-era cannon was determined to be 1,200 feet per second, serving as the benchmark for testing the stone cannonballs.05:23
🪨Sandstone, limestone, and granite were chosen for the stone cannonballs due to their varying hardness and availability in 15th-century Europe.08:47
📦To protect the antique cannon from damage, the stone cannonballs were packaged inside cardboard canisters before being loaded and fired.14:46
💪The sandstone cannonball, despite being the softest, still caused significant damage, penetrating one layer and destroying two bricks before shattering.20:47

Chapters

0:34Introduction to the Stone Cannonball Myth
2:15The Plan: Testing Stone vs. Cast Iron Cannonballs
3:34Calibrating the Cannon with Old Moses
11:53The Cannonball Misfire and Safety Review
13:32Selecting the Right Rocks for Cannonballs
15:47Crafting the Stone Cannonballs
22:14Calibrating Stone Cannonballs to Battle Speed
28:20Building the Castles for Impact Testing
31:48Testing Stone Cannonballs Against Castles

The digest

The annals of 15th-century European warfare whisper of a peculiar tactic: the use of stone cannonballs. In an era where cast iron was a valuable commodity, susceptible to retrieval and repurposing by the enemy, the idea of a projectile that could deliver devastating force yet disintegrate upon impact held significant appeal. The MythBusters team, known for their rigorous scientific inquiry, set out to investigate this historical claim, delving into the physics of ballistics and the geological properties of various rocks.

The Cannonball Conundrum: Resourcefulness vs. Destruction

The core of the myth lies in the European cannoneers' reluctance to fire their precious cast iron cannonballs. Two primary reasons underpinned this hesitation: the enemy could easily retrieve and refire the cannonballs, or, perhaps more cunningly, melt them down to forge their own artillery. This presented a strategic dilemma, prompting the alleged innovation of stone cannonballs. The theory was simple yet profound: if a stone cannonball could match the destructive power of its metal counterpart but shatter on impact, it would deny the enemy valuable resources and ammunition. This ingenious solution, if true, would have been a game-changer in medieval siege warfare, offering a sustainable and unrecoverable form of projectile.