Came across this picture, in which the 37mm M3 has a modified gun shield. Obviously it is done in order to disguise the gun by "breaking up" the shield silhouette, but I became curious as to which extent such mods were applied, and how efficient such a simple mod could be (obviously until the gun lit itself up by firing) in an ambush. Other pictures of similar modification and AT gun camouflage in general would be welcome, though I realize that there may not be many available due to different factors.
