I used to say it as "car-byne", but I switched to "car-bean" a few years ago for some reason. I think the latter is just easier to say. Most people into firearms tend to pronounce it that way too.
car-byne because I’m ESL and watched to many american movies
said it a few times and noted that I'm such an esl that I say it like cara-bin because in my ESL it's pronounced with two a's