Does a 70 mm nitro proof on a Damascus barreled shotgun mean it is safe with modern 2 3/4" loads? Thanks.

Andy:

We need more information, but generally no. I assume from the information given that the proof is British. If so, 70mm Nitro Proof means that it's safe for the modern 2 3/4" BRITISH load marked on the flats - 3 tons/850 BAR; 3 1/4 tons/1200 BAR, etc. - NOT 2 3/4" American (SAAMI) loads.

What kind of gun is it, and what are the proof marks on the flats?

Contact the manufacture of the shells your using and if are the same or less pressure then your o/k. Or handload. All the loading manuals give the loads pressure.