Have you ever wondered if gun calibers and guitar gauges are the same? Well as far as I can tell, they are! [Fun Fact I can't check gauges punch drunk.] The smallest the caliber would go is .11 and that just [kinda] fit into the smallest of Lula's nut slots [her nut is fitted!]. I couldn't really tell the size with the strings in, but I got a slight idea.
The largest of Lula's slots will probably fit .67 and I have yet to check the basses.