Choice of the Special Forces?

It seems like every gun-related product is “the preferred choice of US Special Forces” or “used by US Special Forces”, but never have any citations for those claims. Many of the claims seem to be mutually exclusive (e.g. Company A advertises that their product is preferred by SF, while Company B makes the same claim about their product).
I wonder where one could actually find quantitative data listing precisely what products are indeed used by Special Forces and, out of those used by SF, which are preferred.