I build these from scrap lumber for the local range.
They hang on to the side of the bench top.
Couple of uprights, couple of cross pieces, corner brace and some fiberglass screening.
Set on the bench or deck for prone use
The screen wraps around the back of the end pieces/stabilizers
and is stapled to the upper and lower crosspieces making a full length catch.
A small opening at the bottom right end of the catch
allows the brass to be swept by hand or tilted to the hole and into the recycle bucket.
No brass on the deck, even works with AR's
The top to bottom corner fold catches the rear slung ejects.
Make them whatever height you like, whatever length.
Cheap, durable, portable