The new M320 grenade launcher for the US army comes with an attached day/night self-leveling sight and hand-held range finder similar to commercial ones used for hunting that the grenadier carries. It slows down the rate of fire but can improve the accuracy if the grenadier is well trained.
Also, the South African MGL-1 (OBAT 52, weapon 124) had something silly for accuracy--it may have been as high as 6 or 8. I'm not sure because I edited mine down to match the rest of the GLs.