The CIP is based in Belgium and governments sign up to it.
It specifies chamber sizes and pressure testing for proof and all ammunition makers have to conform to corresponding regulations on cartridge size and pressure. This means all CIP stamped ammo is going to fit in and be safe to use in all CIP proof tested shotguns and rifles.
I can see the logic. You don't want to turn up in Portugal for a shoot and find the rim depth in your gun is too shallow and you cant close it on the local ammo etc.
However, it does seem that gunmakers no longer make guns and the proof house test them as fit for purpose. Now gun makers make guns that suit the proof house. This will lead to guns being made heavier than desirable to build in insurance against more stressful proof testing.
My meeting with the proof master is tomorrow.
