f&b can mean many different thing and can be many different levels of work. some guns must have heavy f&b to get them to run right. some don't need much, just a cleanup and other don't need any. f&b can be a trigger job, work on the barrel, rails, etc... it can be a mix and match of work that you do to make your gun run better. when i buy a gun (new or use) i clean up the feed ramp and sometimes do a trigger job and spring change out, so you can say i did some f&b by doing this.