Quote Mickey :”larcher
I'm not sure of your question. If you are asking how accurate a Double should be I would say minimum of 3" at 100 yards. Anything less is useless and needs to be fixed. This can be by changing the loading or getting the rifle re regulated.”

Sorry I am not as fluent in English as I would like. I am saying that if you use a double to snapshot, you don’t need to meet narrow groupings.
The trouble with double grouping is what you want at 50 and 100 yards taking barrels’ variable converging and overheating.
Few barrels are exactly parallel, in this case the distance between both the POI remains even.
They converge up to the same hole at 50 or 100yds. If the grouping is tight at 50, it will be broader at 100yds and vice versa.
Worse, heating intervenes. Gunsmiths told me the barrels are regulated waiting 5 to 10 seconds between the 2 shots. Tradition is so. Stupid for when we miss we are shooting the second barrel in less than 1 second.
From all of these considerations, it results the grouping is depending of the shooter’s choice.

I see you are no green horn concerning boar and driven hunts. I asked You in a former thread if You’ll happen to hop not far from France when hunting in Europe.
I’ll be glad to invite You. Just know that I am living close to Germany, Switzerland, Luxemburg and Belgium.

André,
As I can take hold of You : on a thread on AR forum I rejoiced myself at having a Dumoulin 375HH endorsed by Ganyana who put FN rifles high on his culling agent wishing list. After ErikD thought it's Mauser’s,

I am legitimately doubting wether Dumoulin is using FN mechanism? You are the most qualified to provide an accurate answer.

Once again, congratulations, wonderful groupings.
Perhaps I'll test my Chapuis this afternoon. Nothing fantastic to be awaited, I am no sharpshooter and my Chapuis is just right out of the box like the ammos for which she is regulated.