My cat got outside for the first time. He came back limping. He wont let me get a good look but the bones seem ok does he need a vet?

Possibly.

Cat fight wounds are very common and tend to abscess.

There might be a tiny puncture from another cat's tooth, bacteria is in the puncture, the skin seals over very quickly so you may not even be able to find a wound. But that bacteria turns into a pocket of pus/infection under the skin. Eventually it will swell up and rupture. Usually takes anywhere from about three days to a week.

Anyways, your cat's limping is not an emergency and no one here can diagnose him, but if it's not better in 24 hours or if you see a wound, swelling, red spot, see him licking it, etc. then you need to have him checked out.

All I know is that sometimes Tom (one of our indoor-outdoor cats) will come up with a "mystery limp" that always goes away after a couple days. Hopefully, yours is no more serious than that.

I hope he hasn't been run over. Best to supervise his out time for now.