I’ve often thought about building a pistol range in my basement by installing 100 linear feet (or 50’ depending upon budget) of underground 36” or 48” box culvert, starting from a basement wall (w/bottom of the culvert about counter-top height above the floor), and extending out in to me yard.
A manhole access in the final box-section would allow for maintenance, and for retrieval of lead.
“I’ve often thought about building a pistol range in my basement...”
Look at buying a couple of old metal shipping containers. Burying them end- to- end under your lot would give you a nice 20+ meter pistol range as well as a hurricane/tornado shelter. A bit of sound proofing and nobody would even know you’re there.