I know this doesn't answer your main question,but about the mag.well (lower), I have a Belgium STG that I put an Imbel on and love it. Check it,maybe they make an inch type that will work with your rifle. It doesn't have the fluting around the edges,said to be a weak point on the,"right arm of the free world".
The rest of the world gets it,why can't we?
"The United States can survive a Barack Obama,who is, after all, merely a fool. It is less likely to survive a multitude of fools such as those who made him their president".
Out of the Czech Republic