Boots,
You might try building a frame in front of your bench that will hang a row of old tires to shoot through. An old kiddie swing set would work just fine, with a set of pulleys to raise and lower the board that the tires are hanging on. With the adjustable tire height you could either shoot from the bench or off-hand. You would be shooting through a rubber tunnel. That should quieten things down a bit. :-)
Best,
TnNuc