Trouble getting past the arms...

So, I got down to the last three rats at the old size and figured I should probably go ahead and try to get her to eat the new one. She ate it last time after wrestling around with the thing and smashing it against the wall by the arm a few times.

This time, she got it by the head nicely, but she's been sitting here a while struggling to get past the elbows. I'm sure she'll eventually get it, but should I be sticking to the last 3 of the smaller size a little longer? Or would it be worse to go back?

The new size is about 100g and "empty" she weighs 850. The size looks appropriate, but she just has trouble with those elbows.

100g sounds like a really big rat for an 800g snake. They really, really don't need meals that big. It's a good way to get them to become sporadic eaters.

There's no such thing as "too late" to go back to a smaller size. Well...maybe too late at THIS particular moment... :P But you know what I mean. Use smaller prey for future feedings.

I thought the general rule for weights was 10-15% of the snake's weight? 850* 10-15% would be 85 - 127.

Granted that I didn't plan on jumping her up this soon, but I misjudged when I ordered online last. I'd like to avoid ordering another round of the smaller ones if possible since I think she's going to out grow those before she goes through another bag of them.

Is this really unhealthy for her?

"Unhealthy"? No, not really. But if you want a ball python that is most likely to eat consistently and predictably, then it's best to stick with smaller prey items. I've personally never bought into the "10%-15%" guideline. If a ball python is fed on a regular schedule...especially if it is a 7-day schedule or thereabouts...they don't need big meals...period. A moderate sized meal eaten every week still adds up to far far more than they'd actually eat in the wild.