The Lefever Model 4 Vent Rib Double Trap was a less graceful gun than the Model 5 or 6 Lefever A Grade.

According to Walter, the Model 4 began at serial number 285000, and the last entry was 285297 with a lot of blanks near the end. So, only about 250 made. Production being in 1929, 30 and 31.
Here is a Model 5 Lefever A Grade 20-gauge, optioned up with single trigger, beavertail, recoil pad and twin ivory sights --

If it had ejectors it would be a Model 6. Lefever A Grade serial numbers began at 300000 in 1934 and ran to 302496 in 1939.