At Mass Rifle they're due at the end of the year. According to the dues notice I got I would cease to be a member (and need to pay another initiation fee, etc.) come January 1st if they didn't have check in hand. I got the dues notice two or three months beforehand.
[Edited to add]
I just checked the website and the "membership year" is October to September. So, dues notice in September, dues due in October, must be paid by the end of December.