In my opinion the CDI bottom metal isn't the quality that the Surgeon, Badger, and PTG stealth is(when PTG makes it right).
Those brands, and a couple other like APA maybe, I can't remember, do it right. The mag is held in place both upward and downward... meaning the mag is not only held in from falling out the bottom, but is held from being pushed upward too much and rubbing against the bolt.
The last time I saw a CDI, it did not properly stop the mag from being able to travel up too high and hit or even block the bolt.
Get a Surgeon or Badger and have some one good inlet/fit it. Buy once and cry once.