Were there serial numbers or anything identifying on the rentals? Secret engravings? It'll be hard to prove they were your rentals unless you have engravings and they weren't scratched off or anything (don't say where the markings are publicly in the thread just in case this thread is being looked at).
I was reading a thing about this exact topic a couple weeks ago
where a guy had 4 real steel guns stolen in addition to 40 "replicas" (I'm assuming a mix of airsoft and pellet guns). If the guy(s) who stole his guns gets caught, they're going to be really fucked because of the real steel thing. That said I think the title of the article I linked to is a bit sensationalist.