Does anyone know when this label/warning became a standard stamping on water tables/barrels?

The gist of my query is the safety of shooting lead round balls in BP Percussion shotguns with Damascus, Twist, Stub, etc barrels with BP proof marks, but without this stamping.

I've both seen as well as own guns of this ilk that have continually handled proper, stiff BP charges and shot amounts with aplomb.

Would the pressure variance be so great as to negatively impact the safety of gun and shooter if lead shot was replaced with lead ball?

We are fortunate in that this board/site has many members extensively learned in the sciences applicable to a situation such as this, and I am appealing to you for help. Your considered replies will be most appreciated, as well as highly regarded.

Having said that I must add that ANYONE, regardless of education and/or vocation who has collected empirical evidence on this topic are, indeed, also MOST welcome.

It's an open invitation to bone up on an obscure vintage gun question before leaping into the wild conversational gaggle at The Southern, where every arcane corner of vintage gun knowledge will surely be ousted into the light. A dry run, if you will.

But for me this isn't merely an intellectual exercise; It holds the promise of life-changing action.

Again, I warmly thank you for any and all contributions you can offer. Your obedient servant - Marc