Bushing comps are a waste of money. They are expensive bushings and poor compensators.
The effectiveness of a comp is determined by its ability to trap and redirect the expanding gases. To do this, the exit holes for the bullet should be kept as narrow as possible. A bushing comp is limited by the large exit hole required to allow the barrel to pass through. The exit hole on a fixed comp is limited only to the diameter the bullet.
To give an example, the EGW Bushing Comp has an exit hole of 0.590", which equals ~0.138" greater than bore diameter for a .45 ACP. Contrast that to a regular compensator from EGW which has an exit hole ~0.012" greater than bore diameter. Some 'smiths can hold that tolerance even tighter.
Save your pennies and buy a real barrel/comp kit.
Best wishes,
Daniel