Hi Mauser8x57
In Europe where double are commonly used, gunsmiths prefer to use real double rifle receiver and no shotgun one because of the diameter of firing pin and firing pin hole which are larger on the second. When using some powerful rifle cartridges the primer can flow down around the firing pin, in the firing pin hole making the double almost impossible to open. Sometimes the shotgun receiver are weaker than the one for double rifle. For such conversion goes to lower pressure cartridges like the old euro standard 8x57R, 9,3x74R, 303 or the US 30Army. If it's a shotgun receiver you will stay away from hi pressure rounds like the 7x65R or the 30R Blaser. On a real double rifle action these two cartridges are OK. I don't know the "know how" of the gunsmith who transform such firearm but always keep in mind that regulation of double is time consuming and expensive to realise (except on new models with adjustable regulation). The longer range you want to have your convergence the most difficult it is to realise.
If you go to such deal you can also have a look at the 405 Winchester. At the beginning of 20th century Belgian and French company made some double in this caliber that were wery well appreciated for wild boar, red stags and even Africa big game by colon leaving there.
Chapuis is making lovely small caliber SxS double on real 28 gauge receiver in 30-30, 6,5x57, 7x57 but they are rather expensive.
I lived some years in Canada (east and west) where game is the same as yours (mostly): if i had to select a caliber, it would be 9,3x74R because it has a great margin of power and can deal with small whitetail to the biggest bears or giant Yukon moose.
But that's an opinion from a non too appreciated (by US people)french frog on an US forum...
Dom
