JK 155 LT Compensator End Cap

End caps, or front caps, allow you to customize your suppressor by changing the bore aperture for better sound performance, adding flash hiders for low-light shooting, and even brakes to reduce recoil.

Generally, endcaps that match the projectile size will have better sound performance, i.e., using a .223 endcap on a .223/5.56 AR15.

End cap strikes are not common when parts are properly installed. Ensure your silencer and muzzle device are correctly torqued, and the alignment is concentric. You can verify concentricity using an alignment rod. 

Many silencers use replaceable endcaps and can be easily swapped out.

As long as the end cap is larger than the bullet, it will work. For example, a .30caliber endcap can work with .223, 6.5, and .308 cartridges.