A bit off topic, but here's my SR22 with the Promag attached:
A closeup of the Dremel work needed to make it fit:
http://lh3.googleusercontent.com/-mW3xQ_Uiw4k/TsB-x8z_mHI/AAAAAAAACDc/rN1bMXRgEBk/s800/IMGP8168.jpg
I cannot comment on reliability as I have not shot it yet.
Very nice looking. Good job. If it was me, i'd buy an airsoft magpul magazine and slip the promag magazine in it. Would look even more like an AR!