The gun should function fine if you just remove the FPB and spring, but you won't really realize the advantages of removing the FPB until you remove the lifter. I've been told that the gun will function fine if the lifter is just removed, even without the spacer to take its place. Alternatively, you can "make" a spacer by just cutting both the legs off the lifter. CZCustom was sold out of the spacer last time I removed the FPB on a pistol, so I just used this latter route and lopped the legs off of the lifter.