Let's see--we'll start with a .416 Rigby and a .425 Westley Richards, and then a .450 Rigby, and a .458 Win Mag, and a .458 Lott, and of course a .470 Nitro Express, and a .500 Nitro Express, and a 500 Jeffrey, and a .505 Gibbs, and a .577 Nitro Express and a bunch of other old European & British big bore stopping rounds...Thankfully the Nitros were all from big, heavy double guns so they weren't all that bad...the rest you knew about...after 5 or 6 shots from any of them you begin to feel it and it feels like a 10 bore on steroids. I'm too chicken to try the .600 Nitro Express let alone the .700 NE...
One that really hurts is a 1895 Winchester Lever shooting the .405 Win without a recoil pad on that crescent butt--ouch...
Was eight and a half and "Grampers" decided to let me go goose shooting with the menfolk and gave me an old Long Tom 12G 3" single shot with a 36" barrel to use...use it, I couldn't even lift it...told me to place it on the fence post or wire (whichever was better) as a rest and just hunker down behind it, aim and shoot...worked fine until I did shoot...had a bruise from my eyes to below my chin, my whole shoulder area and the base of my spine and butt from where I landed sitting on the rocks about 5 feet back of where I was standing... and the fate worse that death was that I missed the bird, wasting one of his very special goose reloads...Boy, did "Nana" ever give him heck when we got back to the farmhouse.