The .243 Win is indeed considered as the made-to-measure roedeer caliber. However, in this country it's legal for roe only as for other big game (wild boar, red deer, mouflon, fallow deer) a caliber > 6,5mm and 2200 J/100m is mandatory. OTOH, I've shot and seen many roedeer shot with different calibers and have found the bigger calibers more decisive in terms of drop down or shorter fleeing/tracking distance).