[skullworks]

Bill;

All the big boys use a monster broaching machine to finish the mag well.

Its quick, easy and almost idiot proof and the size will remain consistent as the broach wears so they only need to gage one about every 50 units.

That said for custom shapes Wire EDM is the easy way - but its going to cost - as in just the wire cut will cost you more than the out the door cost of a name brand receiver from your local gun shop.

You CAN completely machine the mag well yourself. Its a pain but it is doable. There are 2 options.

1] Is standard drilling and milling complete with some hand filing fitting.

2] Is based on the above but adds a step - You will make a guide block that will fit in the mag well as machined and has a corner step milled in it on diagonal corners to act as a guide for a keyway broach. You have to broach each corner twice, once for each side of the 90 degree corner.

I was a Type 07 for 12 years... I made many AR's - its not brain surgery.