Ass backwards if you pardon the pun...
I know the general advice seems to be that they just occasionally swallow tail first and that as long as they succeed there is no need to worry.
I just watched Monty struggle to eat a largish weaner rat backwards and it didnt loook like much fun. I'm sure he has done it before - I don't usually watch the whole process. I know he ate the rat pups backwards frequently.
Lately his feeding response is sitll fierce but he seems to have forgotten how to eat. He often spends a few hours trying each way - I've seen him chomp down on tail, mid section, back legs.
He's nearly 18m old and is about 850g. He gets one weaner f/t rat a week unless he is in shed and very rarely does he pass on a meal.