FBI Evidence Proves Oswald's Ammunition was not Capable of Sufficient Accuracy to Kill JFK

[Bob Prudhomme]

As a comparison, here are the specs for an American rifle known as the .308; derived from the NATO cartridge designated as 7.62x51mm. The number .308 is misleading, as this is actually the bullet and groove diameter of this rifle. In reality, its calibre is .300, the same as the 30-06 Springfield. This means, of course, that the rifling grooves are each .004" deep.


.308 Winchester maximum C.I.P. cartridge dimensions. All dimensions in millimeters (mm) and inches.
Americans would define the shoulder angle at alpha/2 = 20 degrees. The common rifling twist rate for this cartridge is 305 mm (1 in 12 in), 4 grooves, Ø lands = 7.62 mm, Ø grooves = 7.82 mm, land width = 4.47 mm and the primer type is large rifle.[SUP][8]



Notice the groove diameter given as 7.82 mm, which converts to .3079" (.308"). This is because its NATO designation as 7.62 mm measures the diameter across the tops of the lands, or the calibre, while Winchester chose to use a designation measuring the diameter across the bottoms of the grooves. If we convert 7.62 mm to inches we get, of course, .300" or .30 calibre.[/SUP]