Comparison of Bore and Calibre The following information comes from The Book of the Pistol and Revolver by Hugh B. C. Pollard. The Book of the Pistol and Revolver is also available to purchase in print. Table I: Comparison of Bore and Cailber (Click to Enlarge)Bullets to fit these bores should be .02 less in diameter.*1 oz. spherical ball**1/2 oz. ball Table II: Small Bore Gauges (Click to Enlarge)*Kentucky “pea rifle” size. Click here to purchase The Book of the Pistol and Revolver in paperback Return to The Book of the Pistol and Revolver Table of Contents