Mr. Wolverine had a thread dedicated to this. This is the rifle that they experimented with. They stated that they would not want to be doing this work on a regular basis as the bolt hold back device was difficult to fit. If they had a hard time, I am guessing it would be beyond the skill of most with a dremel.
Only disappointment was that I just bought 5 mags.
As stated this one was purchased from wolverine supplies, I do not see them on their website, so I do not know if they are still available.