I had a similar problem when I put on my ATI. Seemed the spring well was not deep enough. When assembled, and I pressed the release, I could see that the spring was fully compressed and still the release was not far enough in to let go of the mag. I sat for about an hour, taking off like a 1/4 of a ring at a time, re-assembling the whole thing each time, till I got the release to clear the mag. Still has plenty of spring power to keep the mag in, and just does let it release. Take a look at it with the action out. I suspect you will see a similar problem. IF you deside to start trimming the spring, go in tiny, tiny steps. You don't want to remove any more than is absolutly necessary. Just my experience with the ATI, YMMV.