As for 7.62mm CHS gauges, in Britain, we had MANY variables. BUT, so far as this forum is concerned, we only had ONE set for bolt action rifles..., from the L8 series, right up to the L81 and that is 1.628 GO and 1.635 NO-GO. The other sizes relate to machine guns where heat, expansion and locking/unlocking methods all come into play.

On the basis that these figures are correct for Britishicon made bolt action 7.62mm rifles, then I see no reason why these figures should not be absolutely correct for Indian made Enfield Riflesicon.

The problem is anyone can make a 7.62mm gauge and call it, well, whatever they like! Ours are all calibrated from a diameter around the neck to the base. I can check the calibration of your SAAMI gauges against ours