The minimum Ballistic requirements for England and Wales are different to those in Scotland. South of the border a rifle of greater than .240” firing a bullet which produces over 1700ft/ lbs of energy at the muzzle is the minimum. Effectively the .243Win caliber using a bullet heavier than 80grains. In Scotland it depends on which type of deer you shoot. For Roe only, a bullet over 50grains, a muzzle velocity over 2450ft/sec and a muzzle energy over 1000ft/lbs are required. For any deer, a bullet over 100grains, with a muzzle velocity over 2450 ft/sec, with a muzzle energy over 1750ft/lbs are the minimum requirements. This means that while the .22 centre fires are OK for Roe, the .243Win is again the smallest caliber for any deer.