Rifle range at home?

[ksubuck]

I bought a piece of ground in the middle of flat farm country this winter. Closest neighbors are 3/4 mile to north, 1 mile to west, 1 mile to south, and 2 miles to east. I am the last person on the maintained section of road and have one car that passes each day (mailman). I want to build a rifle backstop without having to haul in a mound of earth and without spending a ton of money.

I have plenty of unused concrete blocks and railroad timbers, some sand/gravel mix, and a little extra dirt laying around.

My plans are to build a U-shaped wall out of blocks that is 8 feet wide, 8 feet deep and 6 feet tall, then stack timbers across the middle to form a dead space that I will fill with sand/gravel mix. Then I will push dirt up the face of the timbers. I plan on placing this backstop in front of two old silos on the property for an added measure of security for the neighbors to the east.

My question is, does this look safe, should I still be concerned about riccocets? Any thoughts or criticisms much appreciated.