You should read the article before you ask the question.
"By drilling a hole at the rear of the gun barrel, the team found they could release the gas shock wave from the gunpowder . To maintain the bullet's speed, they developed a new design with a high-strength seal at the back and an electromagnetic induction chip inside.
When the firing command is given, the chip ignites the explosive, launching the bullet. As pressure rises, it breaks the membrane and vents through the hole, reducing recoil and maintaining high muzzle velocity."
