What size mouse or rat???

I've been flipping through threads on BP.net and I see that some very young BP's are eating adult mice (I believe that's what some said anyway).
I feed my oldest BP two adult mice every 5-7 days. He's been putting on a good amount of weight (I think!) but he was underweight when I got him.
Now I'm confused as to how old he may be. Petco said about 6 months, but I'm not sure. He's easily 1.5 feet long and 2 or so inches in circumference.
I have a baby ball python for comparison but that's the only BP that I am confident in with my age estimate (1-2 months old). He (Nergal, whom this post is about) is a LOT bigger than her.
Am I not feeding him enough? :/ Should I try rats instead of mice? I don't know that he'll eat F/T rats, but I could see.
What size of rat should I try?
I need to get a scale, too--I have no idea how much he weighs. Probably close to a can of soda's weight is my best comparison without a scale.
Thanks a lot.
Shellie

you could try a small rat

Yeah i would go small rat for him, if he will eat mice well, he should do the same for rats or even rub your rats on the mice for the sent and he should get the hang of it.

I usually start my hatchlings off on rat pinks, that way I don't have to worry later about getting them to switch to rats, or having to feed multiple prey items because they won't switch. I would agree, a small rat should be a good size. If he doesn't seem to want to take it, you can always rub the rat really good with a mouse, all over. The year old pastel het clown female I just acquired a couple of weeks ago I was told was a rat eater, but she is NOT. She eats mice, and will only take one at a feed:(. She also should be eating a small rat. So she is my project now to get switched over. I want to get a few feeds into her before trying to switch her. Good luck, and there are lots of tricks to get them switched.

The big thing for me is just that the snake eats consistently and an adequate amount.

Now, obviously if we were talking about a 6 year old 5 foot long female, 2 mice ain't gonna cut it. But, since he's still fairly young { you think } and relatively small, 2 mice may not be ideal, but he should not starve on them.

Now, think of a few important clues. Does he eat once a week ? Is he out and hunting for more food within a day or two, or is he content until right before feeding time again ? Is he bigger than when you got him ? Does his backbone stick up prominently giving him a sharp triangular appearance or is it just barley noticeable ?

You can of course try him on a small rat, just a little bigger than his mice for now. If he takes it wonderful, if he doesn't yet, don't fret about it. If you are really worried about him, try offering three mice. If he's still hungry, he'll take a third. If he just kind of pushes it around or seems un-interested, he's full. I do this with all 12 of my snakes, if they are hungry they eat, if not they don't. Now I'm sure there are snakes out there who would gorge themselves silly, but none of mine do. So, start off slow and go from there.

Gale