American Handgunner July/August 1979

In Re~o/~e"sBy Claud S. HamiltonBarrel sel up in lathe ready 10 belurned down .003 for Ihe nexllesl shool.26The gap between the forward face ofthe cylinder and the barrel shank is asmuch a part of revolvers as two legs are ofa man. Oh, there have been efforts to overcomeit as a problem-most notably theold Nagant revolver made in Russia andEurope in which the cylinder actuallymoved forward to enclose a tapered portionof the barrel shank at the moment offiring-but they have proven impractical.Today we tend to rely on fine tolerances tominimize the problems ofgas loss and sidesplatter associated with the gap.Most experienced revolver shooters areaware of the barrel gap and know that it isone ofa number ofelements which tend tocause wide variations in the muzzle velocities.developed by even identical revolvers.I say we know it is one because recentSpeer research has identified a number ofother variables which also enter into revolvervelocity variations. Some of theseare bullet length, weight and diameter.chamber throat size and the type anddepth of rifling. But have you ever wonderedjust how much of a velocity variationdiffering barrel gaps cause?While modern revolver barrel gaps varysome I'd expect a quality gun not extensivelyworn to mike somewhere between.001 and .008 inches. Haywood Nelms, afine young gunsmith from Fairfax, Virginia,fits revolvers that he builds or repairsto .003 inches since he considers thisa good compromise between gas loss andthe possible jamming which can occur ifthe gap ~s too small. What happens in thiscase is that combustion residue and bulletmetal shavings tend to build up at the gapand, in time, can cause cylinder and barrelshank to make contact and drag againstone another. Other well known gunsmithswho built guns for competition use inwhich large numbers of rounds may befired before cleaning sometimes advocategaps of .006 inches. All to whom I havespoken seem to agree that .008 is aboutmaximum.Recently I managed through the kindnessof a friend on Detroit's fine PoliceDepartment to secure a real gem-a Smith(Continued on page 48)AMERICAN HANDGUNNER· JULY/AUGUST 1979