While you cannot exchange because the guns will most likely not be altered by Buds. You maybe able to contact them and ask if they could order it/if they expect to get the 10rd version in stock anytime soon.

No substitutions or removals of any kind. Most firearms ship direct and even the ones from Buds will not be allowed to be altered. Unfortunately that's the rule from Buds Gun Shop. I would add the 10rd to your wish list and give them a week or two too get you the model you like. You are not obligated to buy and will receive email notification when they find the one you want.