n our last tests shooting walls, we tried to line up 4 walls that were 2 feet by 2 feet.
It turned out that the 5.56 deviated so much from its course after the first wall, that it was almost impossible to hit the other walls to test penetration.
So, we built bigger walls. These are 4 feet by 4 feet. They are normal 1/2 inch drywall or sheetrock, as it is called in some areas. We spaced the walls about 10 feet apart to simulate normal across-the-room distances.
We will be trying to see how many walls will be penetrated by the rounds shot today.
Great information here, head on over and read the rest of the article: http://www.theboxotruth.com/the-box-o-truth-14-rifles-shotguns-and-walls/