The male slide is often not of a uniform dimension or simply it is not the same diameter along it's entire length. This is the first thing you need to address. Buy a digital micrometer for $50, yes another fifty bites the dust that reads to .0001 tolerance. Using whatever method you like and using files or sandpaper or stones get the slide EXACTLY the same diameter along it's entire length but still oversize by around.001". If you make it this far, you are home free. Remove a tiny amount of material, try to fit the ferrule, clean the slide then measure again, do this over and over, when you are really close, only use the finest abrasive like 1500 grit paper or finer and use micro papers or Scotchbrite to get a mirror finish. If you take your time and repeat these steps, measuring the slide at front, mid and back each time you will get a great fit. It should be bearing on it's entire length, not jam fitting at the end only.
Another post will deal with polishing the female to a true proper fit which is the goal of every builder. Did I just say "polish up the female", is that HR calling?