Ozhunter what you are holding in your hands in the above pic is my definition of the perfect DGR. It is also a proper English classic design reminiscent of the Rigby with its open grip and short forend.
My ideal rifle would be built with a Mauser action and have a drop box mag for a 5+1 cartridge capacity with the magazine lengthened to 3.5" to accommodate the new generation of long solid copper bullets such as the Barnes TSX and the Woodleigh hydrostatically stabilized in 450 and 480grs.These bullets offer spectacular penetration and reliability at the cost of extending into the case and reducing powder capacity. The longer magazine would allow the bullets to be seated out to compensate for their length.It is not difficult to remove metal from the rear of the mag box and shave a little off the front to achieve this. A Woodleigh HS .458cal, 480gr is 1.466" long compared to 1.261" for a conventional 480gr. That's an extra .2" deep into the case. Allowing for a COL of 3.48" instead of the 3.34" standard would recoup .14" of powder space.
(Please note that .458 Win Mag chambers are designed with very long throats so that seating the bullets out is not an issue).
With these mods I believe the .458 Win Mag could be the optimal DG cartridge.Six quick controllable shots should do the job.
I own a 1960 Browning FN Safari and a CZ 550 American in this caliber and reload from .45-70 levels to max loads with 3.6" COL in the CZ. It makes an excellent short range(<150yd)bear moose and anything you can hit gun with the wide range of bullets available. You also get minimal meat destruction and a big wound channel and if you retrieve a solid copper bullet you can most likely reuse it.