Tobias,
I am quite aware of many European chambers being smaller in diameter near forcing cone, sometimes leading to too short measurement if USA-made chamber gauges are used. In fact, my Swedish and German hammer doubles with original chambers are this way. IF I beleived measurements with USA-made chamber gauges, I would quite erroniously claim these chambers were only about 50 mm!!! Now and then I get message from someone that thinks they have Swedish shotgun with such short chambers!! Because of this, I made chamber gauges to exactly fit dimensions of these chambers. To repeat, measurements of 65 mm on my Swedish hammer doubles is accurate, as is 67 mm on my German ones.
As noted in previous post, with European and South American ammos I have, 1980s Itallian, marked 16X65, and recent Venezuelian and Spanish 16X67 marked ammo does actually have, respectively, 65 or 67 mm hulls. I will continue to be learly of English ammos as regards hull length.
Snart skicker jag ett mail till Tobais@shotguns.se.
Hej då och tack för bra discussion,
Niklas