Swiss bore and GP11 dimensions
Swiss CIP values are:
bore/lands 7.51 mm (0.2957"
grooves 7.77 (0.0.3060)
I just dismantled a GP11 and measured it with my bench micrometer.
The diameter in front of the crimp groove was 0.3030"
The diameter behind the crimp groove was 0.3079"
The diameter is most certainly NOT 0.308" over the full bearing length.
Instead, the short section BEHIND the groove will act as a driving band.
CIP gives the maximum projectile diameter as 7.78 mm = 0.3063"
So, while the rifles may well fire 0.308 bullets without complaining, this will surely lead to a higher chamber pressure and bore wear than that caused by the GP11 cartridge.
But the Swiss barrel will have to be very worn indeed before it loosens up to 300/308 dimensions!
Patrick