I don't know how big your pups are but typically they are around the same size as an adult mouse. I was comfortably feeding pups to my smaller ball python when he was ~100g. You should just go by a feeder the same size as the widest part of his body. If thats what you're doing than maybe you have extraordinary large rat pups
I bought it from a local reptile shop fresh killed. It seemed closer to a weaned than a pup honestly but they said it was a pup.
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