RE: Shooting from 50 or less yards
From the choices you gave I would use the shotgun or 30-30. I would then choose the muzzleloader and bow next.
A" true" 7.62X39 is actually a tiny bit larger in diameter than a 30 cal. A 30 cal measures in at .308 , a 7.62X39 measures.311 With that being said the 7.62X39 is larger in diameter but is alsoLIGHTER in weight. This type of bullet was not inteneded to penetrate and expand inside its target as much as it was to peirce and shatter giving off a shrapnel like effect inside the " target". In most cases , the target being a human.
As far as a hunting round.....It can be used.....and it will kill. But because of its ballistic coeficient and sectional density. This round was not designed to be used as a hunting round anyways.
In my opinion, all your choices will kill a deer, but I would prefer the other four over the sks. But its up to you people will use anything to kill whitetails.