I thought it might be a floating point representation issue (not all numbers can be precisely represented using floating point values), but I checked and it turns out 260 can be.
I don’t do anything with the values to “round them off” or anything deliberate like that, so this is likely more to do with the way rotations are represented in UE4 (as well as many other modern engines).
Quaternions and Euler representation and the conversions back and forth probably introduce this small error somewhere and if that’s the case its simply not something we can fix.
TL;DR: Looked into it, probably an unfixable engine thing.
What we might be able to do though is say cut off the value after the last 3 digits after the decimal as nobody really needs that level of precision.