How long ago?
Can't really say for certain, but most likely sometime between 2015 and just a few weeks ago, but most likely closer to 2015.
You wrote that didn't "tell him to remove any guns" and later denied giving permission to do that, but you also said you gave him keys to both the storage unit and the gun cabinet. Why would he need keys to the gun cabinet if he didn't have permission to use the guns?
There were other items inside the cabinet besides just guns.
At least? This implies that other guns may or may not be missing, but you're not sure.
I have verified that only one gun is missing.
Did your son identify the friend or tell you when he loaned the gun or for what purpose he loaned it or say when "later" is? If he did identify the borrower, do you know the borrower?
No, he hasn't given me a name. He just said that the gun is under lock and key at his friend's grandparents house. However, he did recently admit that the gun has been taken out of state,
What you should do is be a responsible gun owner and report the matter to the police. You can give your son advance warning (e.g., "if the gun isn't back in my possession by March 20, 2023, I will be reporting it to the police.").
Yeah, I'm going to to just that this weekend. Firearm is a
Sig Sauer(FYI)