The flash suppressor was part of a concerted policy to reduce recoil in service rifles. The Americans tried dozens of harmonica shaped gadgets, baffles, fins and holes before settling on the slots. In reality, hanging anything loose on a barrel changes its harmonics, and a Congressional delegation reported that the flash suppressor, castle nut and front sight weren't helping accuracy repeatability. So, if you want to take one component off an M14S to improve the accuracy, the flash suppressor is as good a place to start as any.