Shorter barrels create a difficult situations when it comes to gas systems. The shorter the barrel the shorter the gas system. The snappier the recoil, making regulating gas more of a challenge. Flash and noise are increased, leading to wanting to control that with muzzle devices. Flash cans and linear brakes can help. I think linear brakes are one of the most underrated muzzle devices. But the other options of suppressors can further complicate gas systems.