8x57irs
I have an 8x57irs o/u rifle and am very happy with my choice of calibre. Recoil is relatively mild yet at the same time you are aware that it speaks with some authority (roughly equating to a 30.06 in muzzle energy).
The French think of 8x57 as a smaller calibre when used as a boar rifle, and possibly the larger 9.3x74R is more popular according to the armurier who sold me my rifle.
I have not yet blooded my rifle but it is my intention to use it for both deer and boar and I am confident that it will perform admirably in both tasks. My rifle is accurate if used within its design limitations, which means that I accept barrel convergance limits the use of the bottom barrel to 60m, but by slecting top barrel first and zeroing the scope for this, shots can be taken at all normal stalking distances. 100yd groups from my rifle using just the top barrel average around 1", however I am sure with more load development work improvements will be made.
Reloading is slightly interesting as data is not forthcoming from U.S. sites where this calibre is a rarity, Vihtavouri, Norma and Nobelsport are good sources of information.
Dies are the usual 8mm Mauser (7.92x57) but using shell holders for .44/40 or .38/40 instead. Similar rules apply if trimming cases using Lee trimming kit.