How's this for tolerances?
I recieved in response to some of my questions about Swiss rifles from W+F Bern(Swissgovassemblefactory). At that time I was asking 1911 questions as 1931's were a dream to me. On the W+F barrel data sheet dated 7.10.1992/Szr is a groove diameter given as 7,78 +0.06 mm(actually my keyboard won't do it but the +0.06 is over another zero like +0,06/0 without the / whatever that represents or means) or in inches it shows .3063 +0.024 inch over a similar as above zero. And W+F shows a bullet dia of 7.84 -0.04 mm with a zero over the -0.04 and in inches it shows .3087 -0.016(likewise a zero is above the -0.016.
What does it all mean? 304 thru 306 dia barrels or bullets are real hard to swallow. and I would attribute most if not all to bad measurements and or techs. I remember a long time ago a fellow named Pierre found out a caliper of his was a .001" off for the GP-11 projectile. A mistake that he quickly corrected.
Guisan sometimes posts neat pics of gauges, reamers, and other things showing sometimes interesting manufacturing/tolerance info. Best