Colt patterns did not have a lube groove but did have a rebated base. I have seen some bullets with a lube groove and a rebated base but they weren't Colt patterns.
OK, it looks like the D.C. Sage manufactured rounds for Colt revolvers used a small grease groove in the bullet.
The rebated rim was to allow for either nitrated paper or animal gut wrappers for a self-contained cartridge, but not have it interfere with ramming the cartridge into the cylinder.