Hello, you could try this "trick" Build up a 4 ft burm on either side of the largest culvert pipe you can get without alot of $$ and shoot down range thru it. If its wide enough 3 ft dia u should be able to change rifle angles to multiple targets easily.
The more eatrh that touches the Concrete or steel pipe the less noise. This at least sends most sound to an isolated spot on your property. Jamie