feeding

is it normal for the mouse to be swallowed tail first? i noticed that my ball does this every time he eats

I wouldn't say its normal. Most BP I've seen eat always strike the mouse, suffocate it, then after the prey is deceased they start at the head and work their way down. Simply because when you do that, the legs fold into the body making it easier to swallow/digest.
I'm not sure why your DP is eating tail first, thats cause the legs of the mouse to fold in an awkward position, very unnatural.
I wish I could tell you how my BP eats her prey but she has yet to eat...
and its been over a week since they fed her, I'm starting to get worried. :'(

your ball python might just be a natural butt muncher...

are you feeding f/t? i've noticed some of my snakes eat f/t differently than live.