The first thing that you should know about silencers is that they don’t actually silence a gun. They only suppress the noise. The design of silencers is allot like the muffler in cars in that they have baffles that gives the gasses that are expelled from firing a bullet room to expand. It’s the gas leaving the end of the barrel with the bullet that causes the loud bang. So if it is given room to expand instead of just being forced out the end of a narrow tube, then the noise is much softer.