Different countries, different #'s/sizes.
My 10 bore AYA would blow the base wad out of factory WW ammo and badly flatten the primers- AND, from VERY tight chokes, they barely shot modified patterns, 60 to 65%.
I had to cut the crimps off factory ammo to get hulls, then reload them with known 10 bore loads, but using 2oz shot only.
I worked on the chokes with brake cylinder hones with emery cloth contact glued onto the hone's stone brackets at the same time as testing.
I got the right barrel shooting 94% and the left barrel shooting 96% at 40 yards with #2 lead. It was absolutely deadly on Greater Race (Larger) Canada Geese to a full 80yards.
Too much for ducks, though. With 2 ounces of #5's, it shot the same percentages and put 184 pellets onto a mallard target at 40yards.
I killed 27 snipe with one shot (2 oz. 8 1/2 shot) at about 50yards with it - almost the entire flock on a mud hump sticking up out of the lake. The 8 1/2's were re-claimed shot and opened up fairly wide, but still shot almost 80%. Just about tipped the canoe over. It was close.