Weird WTF jamb?

[grayfox]

If the neck is hanging up on the mag forward edge, this is a common issue for the 6 Arc. Use a dremel and lower the front edge about... 0.12" or so, there's a thread on this. Mark it with a pencil or something first, so you don't dremel too far down. Leave any spot welds on the front facing side in place, I've done this for all my 6 Arc mags.