Chambering

[madmikes]

Whats the difference between a 762X51 and Winchester 308 chamberings?

[Grunt Medic TXARNG]

Dimensionally, almost none.  That is, the case dimensions are such that both cartridges will fit, feed and fire in any rifle designed for either.

The only issue is when firing older military surplus rifles (or rifles made from parts kits with original barrels, or barrels made to original specs) designed for the military chambering - the 7.62x51mm NATO round has a significantly lower pressure level than the civilian .308.  Modern production rifles are proofed to the higher levels, and can shoot both with no problem.  Rifles marked '.308' can shoot the lower pressure 7.62 with no problem.  But if you shoot .308 through a surplus rifle proofed only to the NATO standard (7.62 M1 Garand, FN FAL, CETME, G3 and similar) you may be stressing your rifle with significantly higher chamber pressures than it was designed to take.

Does that completely answer your question?