Do bigger strings damage the nut slot for smaller strings?

Nut slots are never the same size as the strings; they're always slightly larger.

Put some 10s on there, tune it up and double-check neck relief and intonation, and you'll be good to go.

 

It'll be OK.

 

If he didn't slot the nut for them, his 11s probably played and tuned like crud for him.

Going back to 10s will work much better with the nut slots.

I generally slot my nuts for D'Addario EGC25s, which are flatwound 12s: 12, 16, 24W, 32, 42, 52. That covers most gauges of strings that I might install, from 9s all the way to flatwound 12s. In some cases, I need to widen the slots a bit more, like on a guitar or two that use a 54 or 56 E, and corresponding A and D. But for the most part, if you slot for flatwound 12s, you're covered.

Keep in mind that Fender guitars came out of the factory with flatwound 12s up till the mid '60s, and then roundwound 12s well into the '70s. That's how "vintage" Fender nuts were slotted in the factory.

 

we don't know if the nut was properly slotted to begin with. The strings will not fit themselves, maybe over many years they would wear the slots some. The only way to know is to give it a go.

 

I dont think so. Think of it this way, some guitars have fret zero, there are no slots. Seems to work fine. So why would a big slot be a problem?

 

Sure it’s possible for a former owner to have damaged the nut slots installing heavier gauge strings.
Hard to say if yours is fine or not.

 

Well…they can, a bit. But it’s not necessarily a “problem“ worth worrying about. Everyone did this in the 1960s and 1970s, if they were using slinky sets on their Fenders and Gibsons with original nuts.