Dovetail Site Blank on a round barrel?

Lyman 12S Slot Blank dovetail slot blank Marble Rifle #87 Dovetail Slot Blank Filler Black Marlin 001187 Made To Fill Sight Dovetails Flat top blank fills empty sight dovetails on scope-equipped dovetail slot blank Ammo Supply Warehouse RIFLE ALUMINUM DOVETAIL SLOT BLANK -

reel king slot Cast in dovetail slot, available in stainless steel, pre filled with polystyrene Used in conjunction with ties to restrain