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					Originally Posted by jp10  According to FM 23-95 75-MM TANK GUN M2 (MOUNTED IN MEDIUM TANK M3)May 4, 1942, the gun was measured "Length (muzzle to rear face of breech ring)".  I would imagine it would be the same for the 75-MM Tank gun mounted in Medium Tank M4.
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 It's my understanding that the rear of the breech is farthest from the loader and where the bore begins.  This would appear to confirm that the L40 does refer to a bore length of 3007mm.  
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