I have the same flash hider on an M4gery, it works well, I've tried it at night. It however deos nothing to add to the velocity. It mainly is in place to meet barrel length restrictions. I have a PLR-16 also, the muzzle flash and jump are pretty bad. I would geuss thats why the previos owner added the hider. I would replace the long one with a compensator since you don't have to meet any barrel length restrictions.