Sounds like the firing lines at Sacramento Valley Shooting Center, but I see Reade range on your signature block? Although I carried my first SEB with me for the FCN held at SVSC back in 2010, knowledge of those firing lines drove me to shoot F-Open with a bipod!! A 1/4 inch thick piece of plyable rubber glued/sewn full width/length under my el-cheapo Midway prone mat front flap had already passed the F-TR "challenge test" up at the FCN held in Lodi in 2008, that I was not using a "board". On the SVSC firing lines, it performed for me as if it were a "board"...a hardwood floor! Laid out on the chat/gravel, when the reinforced flap was tapped in place with a rubber mallet, this simple, flexible load spreader became as concrete. Barrel torque was tearing up the front rest people; with every shot, rests were wallowing all over the place, and loosing their level. Should I go back to shoot F-Open at SVSC again, I'll bring the same rig. But, also I'll also consider bringing my NEO-SEB w/Pastour brass feet, a large piece of carpet (the wider, the better) with 3 holes up front for the "feet" ground penetrators to push thru and into the chat. With the carpet tapped down about the front rest area.....................................................................you get the picture?
Dan