Have to say Dormin that a 60 ft lb rifle in the right calibre and grain will take out a fox without any trouble at all. Range will have to be considered but it is well within capabilities.
In fact, the fox is not that big an animal and in a confrontation between moggie and fox, the fox is the one that will usually give way to the cat.
Bit like magpies, they look big birds but when it comes to it they are all flash suits, loud voices and no substance underneath.
Any one who thinks otherwise would be well advised to get a big ball of ballistic putty and see what happens when 60 ft lbs energy caomes a calling.
However, range, calibre and grains all play a significant part and max range will be affected by this and ones markmanship. Just because your rifle can shoot 12o yards doesnt mean you should !
Steyr
In a battle of wits I refuse to engage with an unarmed person.
To one shot one kill, you need to seek the S. Kill only comes from Skill