The answer is quite simple really. Double rifles cost lots of money no matter what the calibre.Any one wanting to shoot a deer can pick up any type of second hand gun for a pittance and get his deer.
2nd point there wasn"t a lot of small calibre rifles made compared to large calibre rifles.
I'm lucky ,I got one .Westley Richards in 300 Savage 8 1/4 lbs with 26" barrels and as quick as a whip.The previous owner killed an Elk with it .

good shooting
sbs470