Walmart in Woodlank park (had) a pretty good selection of rifles, including ARs. My boy told me he stopped in there the other day and was told the waiting list is over a year now. Not sure how valid that is, but it's what he was told
Try Ft Collins Co. I was in there last week. The guys were Ok. Said they would call me when a type of gun comes in. Very low on shells as every place in Ft Collins. It is just off I-25 1st exit going north. East side of I-25