As Drew stated above, the Birmingham Proof House confirms that service pressure for a standard proof (old 850 bars) CIP gun is 10,730 psi. I agree that the Damascus barrel warning must be for the US market. You'll probably find quite a few Brit guns with Damascus barrels, nitro proofs and the 1 1/8 shot charge mark. And you'll undoubtedly find some that have passed reproof and are now marked either 3 tons or 850 bars. If your gun carries any of those marks, you should be good to go with those shells.
