If anyone is interested, this is roughly how a comercialy made rubber Gran trap is made.

This top picture is the steel frame that holds the bedplates and the ground up rubber.



The next picture is the bedplates attached to the framework. This also shows the fill line for the rubber. The bedplates only hold the rubber the bullets should never contact the steel if the trap is properly maintained.



The last pic shows the trap filled with rubber. The rubber that we used was more like cubed up than shredded.




The granulated rubber was covered with pure gum rubber sheets which had a great "self healing" properties.

This trap was good for up to .308 ballistics or so. Remember---NO TRACERS with the rubber.

The gran trap dose a great job of stopping the bullet with just basically friction. The bullet is kept intact until the trap gets too full and bullets start banging into each other.

This is another kind of rubber trap. It works fine for a low volume range. It is three rows of the belts in a herringbone pattern. We installed these in mostly crime labs and private residences.


I hope these pictures helped with some ideas that you already had.