# Ammunition and Barrel Interaction: What Happens at the Micro Level When a round is fired, the interaction between bullet and barrel affects accuracy, pressure, and velocity. This interaction varies significantly across calibers. 9mm ammo typically engages short pistol barrels where pressure peaks quickly and dwell time is limited. .223 ammo interacts with rifled barrels des... https://bulkammotogo.com/product-category/223-remington-ammo/